dsPIC® DSC Speex Speech
Encoding/Decoding Library
User’s Guide
© 2008-2011 Microchip Technology Inc.
DS70328C
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DS70328C-page 2
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Table of Contents
Preface ........................................................................................................................... 5
Chapter 1. Introduction
1.1 Library Overview .......................................................................................... 11
1.2 Features ....................................................................................................... 14
1.3 System Requirements .................................................................................. 14
Chapter 2. Installation
2.1 Installation Procedure ................................................................................... 15
2.2 Library Files .................................................................................................. 16
Chapter 3. Quick Start Demonstration
3.1 Quick Start Demonstration for dsPIC33F Device Family ............................. 21
3.2 Quick Start Demonstration for dsPIC33E Device Family ............................. 30
Chapter 4. Application Programming Interface
4.1 Adding the Library to an Application ............................................................. 37
4.2 Memory Model Compile Options .................................................................. 38
4.3 Using the Library .......................................................................................... 40
4.4 Register Usage ............................................................................................. 43
4.5 Packet Loss and Corruption ......................................................................... 43
4.6 PC Encoder Utility (PCEU) Output Files ...................................................... 43
4.7 Resource Requirements ............................................................................... 44
4.8 API Functions ............................................................................................... 47
4.9 Application Tips ............................................................................................ 61
Index ............................................................................................................................. 63
Worldwide Sales and Service .................................................................................... 64
© 2008-2011 Microchip Technology Inc.
DS70328C-page 3
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
NOTES:
DS70328C-page 4
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Preface
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools and
documentation are constantly evolving to meet customer needs, so some actual dialogs
and/or tool descriptions may differ from those in this document. Please refer to our web site
(www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom of each
page, in front of the page number. The numbering convention for the DS number is
“DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the
document.
For the most up-to-date information on development tools, see the MPLAB® IDE on-line help.
Select the Help menu, and then Topics to open a list of available on-line help files.
INTRODUCTION
This chapter contains general information that will be useful to know before using the
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide. Items
discussed in this preface include:
•
•
•
•
•
•
•
•
Document Layout
Conventions Used in this Guide
Warranty Registration
Recommended Reading
The Microchip Web Site
Development Systems Customer Change Notification Service
Customer Support
Document Revision History
DOCUMENT LAYOUT
This document describes how to use the dsPIC DSC Speex Speech
Encoding/Decoding Library as a development tool to emulate and debug firmware on
a target board. The document layout is as follows:
• Chapter 1. “Introduction”– This chapter describes the dsPIC DSC Speex
Speech Encoding/Decoding Library.
• Chapter 2. “Installation” – This chapter provides detailed information needed to
install the dsPIC DSC Speex Speech Encoding/Decoding Library on a PC.
• Chapter 3. “Quick Start Demonstration” – This chapter describes the
demonstrations available for the dsPIC DSC Speex Speech Encoding/Decoding
Library.
• Chapter 4. “Application Programming Interface” – This chapter outlines how
the API functions provided in the dsPIC DSC Speex Speech Encoding/Decoding
Library can be included in your application software through the Application
Programming Interface.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 5
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
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Examples
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MPLAB® IDE User’s Guide
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select Enable Programmer
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where N is the total number of
digits, R is the radix and n is a
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Click OK
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Optional arguments
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#define START
autoexec.bat
c:\mcc18\h
_asm, _endasm, static
-Opa+, -Opa0, 1
0xFF, ‘A’
file.o, where file can be
any valid filename
mcc18 [options] file
[options]
errorlevel {0|1}
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var_name [,
var_name...]
void main (void)
{ ...
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WARRANTY REGISTRATION
Please complete the enclosed Warranty Registration Card and mail it promptly.
Sending in the Warranty Registration Card entitles users to receive new product
updates. Interim software releases are available at the Microchip web site.
DS70328C-page 6
© 2008-2011 Microchip Technology Inc.
RECOMMENDED READING
This user's guide describes how to use the dsPIC DSC Speex Speech
Encoding/Decoding Library. The following Microchip documents are available from the
Microchip web site (www.microchip.com), and are recommended as supplemental
reference resources.
dsPIC30F Family Reference Manual (DS70046)
Refer to this document for detailed information on dsPIC30F device operation. This
reference manual explains the operation of the dsPIC30F Digital Signal Controller
(DSC) family architecture and peripheral modules but does not cover the specifics of
each device. Refer to the appropriate device data sheet for device-specific information.
dsPIC33F/PIC24H Family Reference Manual Sections
Refer to these documents for detailed information on dsPIC33F/PIC24H device
operation. These reference manual sections explain the operation of the
dsPIC33F/PIC24H DSC family architecture and peripheral modules, but do not cover
the specifics of each device. Refer to the specific device data sheet for device-specific
information.
dsPIC33E/PIC24E Family Reference Manual Sections
Refer to these documents for detailed information on dsPIC33E/PIC24E device
operation. These reference manual sections explain the operation of the
dsPIC33E/PIC24E DSC family architecture and peripheral modules, but do not cover
the specifics of each device. Refer to the specific device data sheet for device-specific
information.
16-Bit MCU and DSC Programmer’s Reference Manual (DS70157)
This manual is a software developer’s reference for the 16-bit PIC24F and PIC24H MCU
and 16-bit dsPIC30F and dsPIC33F DSC device families. It describes the instruction set
in detail and also provides general information to assist in developing software for these
device families.
MPLAB® Assembler, Linker and Utilities for PIC24 MCUs and dsPIC®
DSCs User’s Guide (DS51317)
MPLAB Assembler for PIC24 MCUs and dsPIC® DSCs (formerly MPLAB ASM30)
produces relocatable machine code from symbolic assembly language for the dsPIC
DSC and PIC24 MCU device families. The assembler is a Windows console application
that provides a platform for developing assembly language code. The assembler is a
port of the GNU assembler from the Free Software Foundation (www.fsf.org).
MPLAB® C Compiler for PIC24 MCUs and dsPIC® DSCs User’s
Guide (DS51284)
This document describes the features of the optimizing C compiler, including how it
works with the assembler and linker. The assembler and linker are discussed in detail
in the “MPLAB® Assembler, Linker and Utilities for PIC24 MCUs and dsPIC® DSCs
User's Guide” (DS51317).
Readme Files
For the latest information on using other tools, read the tool-specific Readme files in
the Readme subdirectory of the MPLAB® IDE installation directory. The Readme files
contain updated information and known issues that may not be included in this user’s
guide.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 7
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
THE MICROCHIP WEB SITE
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To register, access the Microchip web site at www.microchip.com, click on Customer
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The Development Systems product group categories are:
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• Programmers – The latest information on Microchip programmers. These include
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CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
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Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Customers should contact their distributor, representative or field application
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Technical support is available through our Web site at:
http://www.microchip.com/support.
DS70328C-page 8
© 2008-2011 Microchip Technology Inc.
DOCUMENT REVISION HISTORY
Revision A (June 2008)
This is the initial release of this document.
Revision B (February 2011)
This revision contains the following updates:
Updated the last paragraph in 2.2.1 “demos Folder”
• Updated the following in 3.1.1.4 “Demonstration Code Description”:
- Renamed the function UART2Init() to UART2_open
- Renamed the function UART2IsReadBusy() to UART2Read()
- Renamed the function UART2IsWriteBusy() to UART2Write()
• Updated the Return Value description for the “Speex8KHzDecode” API function, in
4.8 “API Functions”
• Formatting changes and minor text updates were incorporated throughout the
document
Revision C (June 2011)
In addition to new content in support of the dsPIC33E device family, this revision
includes formatting changes and minor text updates, which were incorporated
throughout the document.
All major documentation updates are described in Table 1-1.
TABLE 1-1:
DOCUMENTATION UPDATES
Chapter
“Preface”
Description
Updated the Recommended Reading section.
Updated the Development Systems Customer Change Notification Service section.
Chapter 1. “Introduction” Updated the first paragraph in Chapter 1. “Introduction”.
Updated 1.1 “Library Overview”.
Updated Figure 1-2 in 1.1 “Library Overview”.
Chapter 2. “Installation”
Updated 2.1 “Installation Procedure”.
Removed Figure 2-1 through Figure 2-5 in 2.1 “Installation Procedure”.
Updated the version number in Speex v3.0 to Speex v4.0, in 2.2 “Library Files”.
Updated 2.2.1 “demos Folder”.
Updated Table 2-1 in 2.2.1.1 “communication Folder”.
Updated Table 2-2 in 2.2.1.2 “Playback Folder”.
Updated Table 2-3 in 2.2.1.3 “Recordplay Folder”.
Renamed the title for Table 2-5 and updated the table, in 2.2.4 “libs Folder”.
Chapter 3. “Quick Start
Demonstration”
Updated the existing section in Chapter 3. “Quick Start Demonstration” to 3.1 “Quick
Start Demonstration for dsPIC33F Device Family”.
Updated the first paragraph in 3.1.1 “Communication Demonstration”.
Updated step 1 and step 2 in 3.1.1.2.2 “Programming the dsPIC DSC Device”.
Updated step 1 and step 2 in 3.1.2.2.2 “Programming the dsPIC DSC Device”.
Updated step 2 in 3.1.2.3 “Demonstration Procedure”.
Updated step 1 and step 2 in 3.1.3.2.2 “Programming the dsPIC DSC Device”.
Added 3.2 “Quick Start Demonstration for dsPIC33E Device Family”.
Updated step 7 and removed step 8 in 3.2.1.2.1 “Configure MEBs and dsPIC33E USB
Starter Kits”.
Removed Figure 3-6 in 3.2.1.2.1 “Configure MEBs and dsPIC33E USB Starter Kits”.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 9
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
TABLE 1-1:
DOCUMENTATION UPDATES (CONTINUED)
Chapter
Chapter 4. “Application
Programming Interface”
DS70328C-page 10
Description
Updated 4.1 “Adding the Library to an Application”.
Removed Figure 4-1 through Figure 4-3 in 4.1 “Adding the Library to an
Application”.
Removed Figure 4-1 in 4.2 “Memory Model Compile Options”.
Updated 4.3.1 “Narrowband Speex Coding Steps”.
Added a note in 4.3.1 “Narrowband Speex Coding Steps”.
Updated 4.3.2 “Wideband Speex Coding Steps”.
Added a note in 4.3.2 “Wideband Speex Coding Steps”.
Updated 4.7 “Resource Requirements”.
Updated Table 4-2, Table 4-5 and Table 4-6 in 4.7.1 “Narrowband-Only Library”.
Updated Table 4-8 and Table 4-10 in 4.7.2 “Wideband and Narrowband Speex”.
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Chapter 1. Introduction
This chapter introduces the dsPIC DSC Speex Speech Encoding/Decoding Library.
This library provides functionality to compress a speech signal, which is useful in
applications that have limited memory or communication resources. The library
supports the dsPIC33F and dsPIC33E device families.
This user’s guide provides information that you can use to incorporate the dsPIC DSC
Speex Speech Encoding/Decoding Library into your embedded solution.
The following topics are covered in this chapter:
• Library Overview
• Features
• System Requirements
1.1
LIBRARY OVERVIEW
The dsPIC DSC Speex Speech Encoding/Decoding Library reduces the number of
bytes required to represent a speech frame. This reduction, or compression of speech
data, is specified by the compression ratio. Figure 1-1 illustrates a typical application of
the dsPIC DSC Speex Speech Encoding/Decoding Library.
The communication terminal shown in Figure 1-1, uses the Speex Speech Encoder to
perform speech compression. It can then store the compressed data in Flash program
memory and transmit the compressed data over a communication link to a remote
terminal. It decompresses the compressed speech data that is received from the
remote terminal by using the Speex Speech Decoder, and outputs this decompressed
speech signal to a local speaker. By using the dsPIC DSC Speex Speech
Encoding/Decoding Library in such an application, the amount of memory required to
store speech data and the communication bandwidth requirement is significantly
reduced.
The dsPIC DSC Speex Speech Encoding/Decoding Library operates at a sampling rate
of either 16 kHz or 8 kHz, and is suitable for the following applications:
•
•
•
•
•
•
•
Voice recording and playback
Voice over Internet Protocol (VoIP)
Communication
Automated announcement systems
Intercom
Walkie-talkie
Any application using message playback
© 2008-2011 Microchip Technology Inc.
DS70328C-page 11
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
FIGURE 1-1:
APPLICATION EXAMPLE
Communication Terminal
Serial Flash
Memory
Microphone
Communication
Network
Speex
Encoder
Speex
Decoder
A
B
Speaker
Remote Terminal
Speex
Decoder
A
Speaker
B
Microphone
Serial Flash
Memory
Speex
Encoder
The dsPIC DSC Speex Speech Encoding/Decoding Library is based on the Speex
Speech Coder, which is an open-source speech compression algorithm and uses the
Code Excited Linear Prediction (CELP) technique. This technique provides a
reasonable trade-off between performance and computational complexity. The library
is appropriate for both half-duplex and full-duplex systems. The library is written in both
C language and the Assembly language.
The dsPIC DSC Speex Speech Encoding/Decoding Library supports four output data
rates (modes), two of which require a 16 kHz sampling rate (Wideband). The remaining
two are supported at an 8 kHz sampling rate (Narrowband). Additionally, the library also
contains a version of the Speex coder, which is optimized for the 8 kbps mode.
The optimized library can be used on devices with 8 KB RAM. Figure 1-2 illustrates the
organization of the dsPIC DSC Speex Speech Encoding/Decoding Library.
The library archive file, libspeex_33F.a for dsPIC33F devices and
libspeex_33E.a for dsPIC33E devices, supports all the four modes (Narrowband
and Wideband). The library archive file, libspeex_8k_33F.a for dsPIC33F devices
and libspeex_8k_33E.a for dsPIC33E devices, is a Narrowband-only version of
Speex and is optimized for the 8 kbps mode.
DS70328C-page 12
© 2008-2011 Microchip Technology Inc.
Introduction
FIGURE 1-2:
dsPIC® DSC SPEEX SPEECH ENCODING/DECODING
LIBRARY ORGANIZATION
dsPIC® DSC Speex Speech Encoding/Decoding Library
Wideband Plus Narrowband
libspeex_8k_33F.a
libspeex_8k_33E.a
libspeex_33F.a
libspeex_33E.a
16 kHz sampling rate
9.8 kbps
mode
12.8 kbps
mode
8 kHz sampling rate
8 kbps
mode
Narrowband Only
11 kbps
mode
8 kHz sampling rate
8 kbps
mode
The library Application Programming Interface (API) provides a set of initialization,
encode and decode functions. The application can use the encoder and decoder
independent of each other, or use them together. It is also possible for the encoder and
decoder to share scratch memories. Multiple instances of the encoder and decoder can
also be instantiated.
The dsPIC DSC Speex Speech Encoding/Decoding Library also contains a PC-based
Encoder Utility (PCEU), which allows speech to be recorded on a PC (through the PC’s
microphone port), and converted to Speex encoded files. These files can then be
included into the user application as a part of the application code, thereby allowing
encoded speech segments to be stored in the device Flash program memory.
Additionally, the encoded data can also be stored in data EEPROM (if the target dsPIC
DSC contains Data EEPROM) and RAM. The PCEU can also encode prerecorded
WAVE (.wav) files, and can accept multiple files as input.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 13
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
1.2
FEATURES
The dsPIC DSC Speex Speech Encoding/Decoding Library has the following features:
•
•
•
•
•
•
•
•
•
•
•
1.3
Simple user interface with only one library file and one header file
All functions are called from a C application program
Full compliance with the Microchip C30 Compiler, Assembler and Linker
Highly optimized assembly code that uses DSP instructions and advanced
addressing modes
Compact and concise API for easier integration with application
Four output modes:
- 8 kbps at 8 kHz sampling rate (Narrowband) – 16:1 compression ratio
- 11 kbps at 8 kHz sampling rate (Narrowband) – 11.63:1 compression ratio
- 9.8 kbps at 16 kHz sampling rate (Wideband) – 26.12:1 compression ratio
- 12.8 kbps at 16 kHz sampling rate (Wideband) – 20:1 compression ratio
Library contains a Speex version optimized for 8 kbps mode
Speex PCEU for recording and encoding speech through a PC
Audio bandwidth of 0 kHz to 8 kHz with sampling rate of up to 16 kHz
Can be integrated with Microchip’s Noise Suppression, Acoustic Echo
Cancellation and Line Echo Cancellation Libraries
Library delivered on CD, which includes:
- Sample demonstration applications with complete source code
- User’s guide
- HTML help files for PCEU
SYSTEM REQUIREMENTS
The dsPIC DSC Speex Speech Encoding/Decoding Library requires a PC-compatible
system with these attributes:
•
•
•
•
•
1 GHz or higher processor
HTML browser
16 MB RAM (minimum)
40 MB available hard drive space
Microsoft® Windows® 98, Windows 2000, Windows NT, Windows XP, or Windows
2007
• Sound card
DS70328C-page 14
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Chapter 2. Installation
This chapter describes the various files in the dsPIC DSC Speex Speech
Encoding/Decoding Library, and includes instructions for installing the library on your
laptop or PC for use with dsPIC DSC programming tools.
The following topics are covered in this chapter:
• Installation Procedure
• Library Files
2.1
INSTALLATION PROCEDURE
The dsPIC DSC Speex Speech Encoding/Decoding Library is available as a zip archive
file, if downloaded from the Microchip web site, or as a CD. Copy the archive file to
your local hard drive, and then extract the files.
To install the library, follow these steps:
1. Double-click Speex setup.exe. The license agreement appears in a new
window.
2. Review the license agreement and click I Agree to continue. The Installation
Destination dialog appears.
3. Specify the location (i.e., directory) where the library is to be installed, and then
click Install.
4. Click Close to close the dialog. This completes the dsPIC DSC Speex Speech
Encoding/Decoding Library installation.
The installation process creates the folder, Speex v4.0, which contains the files
described in 2.2 “Library Files”.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 15
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
2.2
LIBRARY FILES
The dsPIC DSC Speex Speech Encoding/Decoding Library CD or zip archive file
creates a directory titled Speex v4.0.
This directory contains the following folders:
•
•
•
•
•
demos
doc
h
libs
PCEU
2.2.1
demos Folder
The demos folder contains application code examples, which demonstrate the use of
the Narrowband and Wideband modes of Speex in different application scenarios. The
demos folder contains the following folders and sub-folders:
• Narrowband
- Communication
- Playback
- RecordPlay
• Wideband
- Communication
- Playback
- RecordPlay
The only difference between the Narrowband and the Wideband demonstrations is the
Speex mode that is utilized. The archive file used for Narrowband demonstrations is
libspeex_8k_33F.a for dsPIC33F or libspeex_8k_33E.a for dsPIC33E, and the
include file is speex_8k.h. The archive file used for Wideband demonstrations is
libspeex_33F.a for dsPIC33F or libspeex_33E.a for dsPIC33E, and the
include file is speex.h. The demonstration folder also contains a playback application
example for dsPIC30F devices.
2.2.1.1 Communication FOLDER
The Communication folder contains files, which demonstrate the use of the dsPIC
DSC Speex Speech Encoding/Decoding Library in a communication setup that
consists of two development boards communicating speech data over a serial link.
Table 2-1 describes the files in this folder.
DS70328C-page 16
© 2008-2011 Microchip Technology Inc.
Installation
TABLE 2-1:
Communication FOLDER
File Name
Description
dsPIC33F Communication Demo 1.hex
Demonstration hexadecimal file for board 1 on
dsPIC33F.
dsPIC33F Communication Demo 2.hex
Demonstration hexadecimal file for board 2 on
dsPIC33F.
dsPIC33E Communication Demo 1.hex
Demonstration hexadecimal file for board 1 on
dsPIC33E.
dsPIC33E Communication Demo 2.hex
Demonstration hexadecimal file for board 2 on
dsPIC33E.
dsPIC33F Communication Demo.mcp
Demonstration MPLAB Project file for dsPIC33F.
dsPIC33E Communication Demo.mcp
Demonstration MPLAB Project file for dsPIC33E.
cleanup.bat
A batch file script for cleaning the intermediate
build files.
h\Explorer16.h
C header file for Explorer 16 Development Board
routines.
h\MEB.h
C header file for Multimedia Expansion Board
(MEB) routines.
h\speex_8k.h
C header file defining the interface to Narrowband
Speex Library.
h\UART2Drv.h
C header file defining the interface to the UART
driver.
h\WM8510CodecDrv.h
C header file defining the interface to the WM8510
codec driver.
h\WM8731CodecDrv.h
C header file defining the interface to the WM8731
codec driver.
lib\libspeex_8k_33F.a
Narrowband Speex Library archive file for
dsPIC33F.
lib\libspeex_8k_33E.a
Narrowband Speex Library archive file for
dsPIC33E.
src\Explorer16.c
C source file containing routines for the Explorer 16
Development Board.
src\MEB.c
C source file containing routines for the MEB.
src\main.c
C source file containing the main speech
processing routine.
src\UART2Drv.c
C source file containing the driver routines for
UART2.
src\WM8510CodecDrv.c
C source file containing the driver routines for the
WM8510 codec.
src\WM8731CodecDrv.c
C source file containing the driver routines for the
WM8731 codec.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 17
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
2.2.1.2 Playback FOLDER
The Playback folder contains demonstration files that can be used to show the use of
dsPIC DSC Speex Speech Encoding/Decoding Library to implement a playback-only
system. The demonstration will playback encoded speech data stored in Flash
program memory. Table 2-2 describes the files in this folder.
TABLE 2-2:
Playback FOLDER FILES
File Name
Description
dsPIC33F Playback Demo.hex
Demonstration hexadecimal file for dsPIC33F.
dsPIC33E Playback Demo.hex
Demonstration hexadecimal file for dsPIC33E.
dsPIC33F Playback Demo.mcp
Demonstration MPLAB Project file for dsPIC33F.
dsPIC33E Playback Demo.mcp
Demonstration MPLAB Project file for dsPIC33E.
cleanup.bat
A batch file script for cleaning up intermediate build files.
h\Explorer16.h
C header file for Explorer 16 Development Board routines.
h\MEB.h
C header file for MEB routines.
h\speex_8k.h
C header file defining the interface to the Narrowband Speex
Library.
h\PgmMemory.h
C header file defining the interface to routines to read Flash
program memory.
h\WM8510CodecDrv.h
C header file defining the interface to the WM8510 codec driver.
h\WM8731CodecDrv.h
C header file defining the interface to the WM8731 codec driver.
lib\libspeex_8k_33F.a
Narrowband Speex Library archive file for dsPIC33F.
lib\libspeex_8k_33E.a
Narrowband Speex Library archive file for dsPIC33E.
src\Explorer16.c
C source file containing routines for the Explorer 16 Development
Board.
src\MEB.c
C source file containing routines for the MEB.
src\main.c
C source file containing the main speech processing routine.
src\SpeechSegment.s
Encoded speech segment file.
src\PgmMemory.s
Assembly source code containing the routines to read from Flash
program memory.
src\WM8510CodecDrv.c
C source file containing the driver routines for the WM8510 codec.
src\WM8731CodecDrv.c
C source file containing the driver routines for the WM8731 codec.
DS70328C-page 18
© 2008-2011 Microchip Technology Inc.
Installation
2.2.1.3 Recordplay FOLDER
The RecordPlay demonstration shows the use of the dsPIC DSC Speex Speech
Encoding/Decoding Library to implement a voice recorder system. The demonstration
will encode speech data, store it in external serial Flash memory, and will playback this
data when requested. Table 2-3 describes the files in this folder.
TABLE 2-3:
RecordPlay FOLDER FILES
File Name
Description
dsPIC33F RecordPlay Demo.hex
Demonstration hexadecimal file for dsPIC33F.
dsPIC33E RecordPlay Demo.hex
Demonstration hexadecimal file for dsPIC33E.
dsPIC33F RecordPlay Demo.mcp
Demonstration MPLAB Project file for dsPIC33F.
dsPIC33E RecordPlay Demo.mcp
Demonstration MPLAB workspace for dsPIC33E.
cleanup.bat
A batch file script for cleaning up intermediate build files.
h\Explorer16.h
C header file for Explorer 16 Development Board routines.
h\MEB.h
C header file for the MEB.
h\speex_8k.h
C header file defining the interface to the Narrowband Speex
library.
h\SST25VF040BDrv.h
C header file defining the interface to routines for
SST25VF040B serial Flash memory.
h\SST25VF016BDrv.h
C header file defining the interface to routines for
SST25VF016B serial Flash memory.
h\WM8510CodecDrv.h
C header file defining the interface to the WM8510 codec
driver.
h\WM87310CodecDrv.h
C header file defining the interface to the WM8731 codec
driver.
lib\libspeex_8k_33F.a
Narrowband Speex library archive file for dsPIC33F.
lib\libspeex_8k_33E.a
Narrowband Speex library archive file for dsPIC33E.
src\Explorer16.c
C source file containing routines for the Explorer 16
Development Board.
src\MEB.c
C source file containing routines for the MEB.
src\main.c
C source file containing the main speech processing routine.
src\SpeechSegment.s
Encoded speech segment file.
src\SST25VF040BDrv.h
C source file containing routines for SST25VF040B serial
Flash memory.
src\SST25VF016BDrv.h
C source file containing routines for SST25VF016B serial
Flash memory.
src\WM8510CodecDrv.c
C source file containing the driver routines for the WM8510
codec.
src\WM8731CodecDrv.c
C source file containing the driver routines for the WM8731
codec.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 19
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
2.2.2
doc Folder
The doc folder contains the user’s guide for the dsPIC DSC Speex Speech
Encoding/Decoding Library and a help file for the Speex PC-based Encoder Utility
(PCEU). To view either document, double-click the file name. The user’s guide can also
be downloaded from the Microchip web site (www.microchip.com).
2.2.3
h Folder
The h folder contains the C header files, which define the API. Table 2-4 describes the
files in this folder.
TABLE 2-4:
INCLUDE FILES
File Name
Description
libspeex.h
Include file that contains the interface to Wideband mode and Narrowband Speex mode. This file must be included in the application
to use any of the four modes.
libspeex_8k.h
Include file that contains the interface to the optimized Narrowband
Speex mode. This file must be included in the application to use the
single Narrowband mode.
2.2.4
libs Folder
The libs folder contains the library archive files for the dsPIC DSC Speex Speech
Encoding/Decoding Library. Table 2-5 describes the files in this folder.
TABLE 2-5:
LIBRARY ARCHIVE FILES
File Name
libspeex_33F.a
libspeex_33E.a
libspeex_8k_33F.a
libspeex_8k_33E.a
2.2.5
Description
Archive file that contains Wideband and Narrowband Speex functions. This file must be included in the application to use any of the
four modes.
Archive file that contains optimized Narrowband Speex functions.
This file must be included in the application to use the single
Narrowband mode.
PCEU Folder
The PCEU folder contains files required by Speex PCEU. Table 2-6 describes the files
in this folder.
TABLE 2-6:
PCEU FILES
File Name
Description
dsPICSpeechRecord.exe
PCEU executable file. Double-click this file to start the
Speex PCEU.
Speech_WB.dll
DLL files required by the PCEU.
SpeechRecord.dll
DS70328C-page 20
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Chapter 3. Quick Start Demonstration
This chapter describes the demonstration code examples for the dsPIC33F and
dsPIC33E device families, which are part of the dsPIC DSC Speex Speech
Encoding/Decoding Library package.
3.1
QUICK START DEMONSTRATION FOR dsPIC33F DEVICE FAMILY
The following demonstration examples are covered in this section:
• Communication Demonstration
• Playback Demonstration
• Record Play Demonstration
3.1.1
Communication Demonstration
The Communication demonstration shows how the dsPIC DSC Speex Speech
Encoding/Decoding Library can be used to reduce the required bandwidth in a
full-duplex communication type of application running on a dsPIC33F device.
3.1.1.1
DEMONSTRATION SUMMARY
The Communication code example requires the use of two Explorer 16 Development
Boards with two Audio PICtail™ Plus Daughter Boards (not included with the software
license), which are set up as shown in Figure 3-1.
FIGURE 3-1:
SPEEX COMMUNICATION DEMONSTRATION SETUP
Explorer 16 Development Board
with Audio PICtail™ Plus Daughter Board
running Speex Speech Encoding/Decoding Library
Board 1
Explorer 16 Development Board
with Audio PICtail Plus Daughter Board
running Speex Speech Encoding/Decoding Library
Board 2
Headsets are connected to the Audio PICtail Plus Daughter Boards. When a user
speaks into the headset connected to board 1, the WM8510 codec on the Audio PICtail
Plus Daughter Board will sample and convert the data, and provide it to the dsPIC DSC
device through the DCI module. The dsPIC DSC device will compress the speech
signal using the Speex encoder, and then transmit the compressed speech frame data
through the UART2 module and the RS-232 transceiver to board 2.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 21
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
The dsPIC DSC device on board 2 receives the encoded frame through the on-board
RS-232 transceiver and the device’s UART2 module. The dsPIC DSC device decodes
the received frame using the Speex decoder, and then plays out the signal on the
headset through its DCI module and the on-board WM8510 codec.
For a speech signal that is sampled at 8 kHz at 16-bit resolution, the resulting data rate
is 128 kbps. To communicate this data to a remote terminal over a communication link,
the minimum required communication link bandwidth would be 128 kbps. By encoding
the speech signal using a Narrowband Speex mode, for example, for 8 kbps mode, the
minimum communication link bandwidth would be 8 kbps. This results in a bandwidth
reduction of 16x.
The code examples invoke the Speex16KHzEncode() and Speex16KHzDecode()
functions for Wideband, or Speex8KHzEncode()or Speex8KHzDecode() function
for Narrowband from the dsPIC DSC Speex Speech Encoding/Decoding Library, to
encode and decode speech data.
3.1.1.2
DEMONSTRATION SETUP
The demonstration application is intended to run on the Explorer 16 Development
Board with an Audio PICtail Plus Daughter Board (not included with the software
license). The procedure described in this section applies to both the Narrowband and
the Wideband Speex communication demonstration. Use the procedure outlined in the
following section to set up the demonstration.
3.1.1.2.1
Configure Explorer 16 Development Board and Audio PICtail Plus
Daughter Boards
Before applying power, you need to configure the boards:
1. On the Audio PICtail Plus Daughter Board 1, set jumper J4 (O/P SEL) to the
codec position and set jumper J8 (LN/MIC) to the microphone position, as shown
in Figure 3-2.
FIGURE 3-2:
JUMPER POSITIONS ON AUDIO PICtail™ PLUS DAUGHTER BOARD
J4 (Codec select)
J8 (Mic select)
DS70328B-page 22
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
2. Insert the Audio PICtail Plus Daughter Board 1 into the Explorer 16 Development
Board 1 PICtail Plus socket J5.
3. Connect an output device, such as headphones, to socket J10 on the Audio
PICtail Plus Daughter Board 1.
4. Connect a microphone to socket J1 on the Audio PICtail Plus Daughter Board 1.
5. Repeat steps 1 through 4 for the second Audio PICtail Plus Daughter Board and
Explorer 16 Development Board.
6. Connect one end of the DB9M-DB9M Null Modem Adapter to P1 on Explorer 16
Development Board 1. Then, connect one end of the RS-232 cable to the Null
Modem Adapter.
7. Connect the other end of the RS-232 cable to P1 on the Explorer 16
Development Board 2.
8. Once the setup is complete, apply power to the Explorer 16 Development
Boards. The setup will be similar to the setup shown in Figure 3-3.
FIGURE 3-3:
SETUP FOR SPEEX COMMUNICATION DEMONSTRATION
Explorer 16 Development Board and
Audio PICtail Daughter Board 2
Explorer 16 Development Board and
Audio PICtail™ Daughter Board 1
9 VDC
9 VDC
Null Modem Adapter
115 VAC
115 VAC
RS-232 Cable
© 2008-2011 Microchip Technology Inc.
DS70328B-page 23
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
3.1.1.2.2
Programming the dsPIC DSC Device
Use this process to load the Speex communication demonstration into the dsPIC DSC
device on the Explorer 16 Development Board.
1. On your PC, launch MPLAB® IDE and open the dsPIC33F Communication
Demo.mcp project located in the Communication folder. For more information
on using MPLAB IDE, refer to the “MPLAB® IDE, Simulator, Editor User's Guide”
(DS51025).
2. Select File > Import > dsPIC33F Communication Demo 1.hex to import the
project hexadecimal file for board 1, or select File > Import > dsPIC33F
Communication Demo 2.hex to import the project hexadecimal file for board 2.
3. Select Programmer > Connect to link the MPLAB ICD 2 to the dsPIC DSC target
device. The Output window confirms that the MPLAB ICD 3 is ready.
4. Select Programmer > Program. The Output window displays the download
process and indicates that the programming was successful.
5. Connect the MPLAB ICD 3 to the Explorer 16 Development Board.
6. Program the dsPIC DSC device on the board.
7. When the program is loaded, disconnect the MPLAB ICD 3 from the board
(remove the phone cable from the MPLAB ICD 3 connector).
8. Repeat steps 2 through 7 for the second board.
Note:
3.1.1.3
The MPLAB® REAL ICE™ In-Circuit Emulator can be used in place of
MPLAB ICD 3.
DEMONSTRATION PROCEDURE
After the demonstration application has been programmed into both devices, the
application is now ready to run.
Use the following procedure to run the demonstration:
1. Press the Reset button on board 1. LED D3 on the board will light up indicating
that the board is waiting for synchronization to be complete.
2. Reset board 2. At this time, LED D4 on both of the boards will light up indicating
that the boards are synchronized and communicating encoded speech data
frames.
3. Speak into the microphone connected to board 1. This speech will be heard in
the output device, such as headphones, connected to board 2 and vice-versa.
3.1.1.4
DEMONSTRATION CODE DESCRIPTION
The demonstration code runs on a dsPIC DSC device, using the Primary Oscillator as
the clock source with the PLL set for 40 MIPS operation.
The file, main.c, contains the main function for the demonstration application. This
main function allocates all of the variables and arrays in data memory that are needed
by the UART and WM8510 codec driver, as well as the blocks of data memory that
need to be allocated for the dsPIC DSC Speex Speech Encoding/Decoding Library
functions.
The main function calls the Speex8KHzEncoderInit()and
Speex8KHzDecoderInit() functions (or the corresponding Wideband functions for
the Wideband communication demonstration) from the dsPIC DSC Speex Speech
Encoding/Decoding Library, which initializes the Speex encoder and decoder
algorithms to their default and initial state.
DS70328B-page 24
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
The main function also calls the WM8510Init()function to initialize the DCI module,
the I2C™ module, the WM8510 codec and the DCI interrupt. The DCI module acts as
a Master and drives the serial clock and frame synchronization lines. The WM8510
codec acts as a Slave. The DCI module is set for the multi-channel Frame Sync
Operating mode, with 16-bit data words and 16 data words or time slots per frame, of
which only one transmit slot and one receive slot are used in this demonstration.
The dsPIC DSC device will send the control information to the WM8510 codec
through the I2C module of the dsPIC DSC device. Subsequently, the
WM8510Start()function is used to enable the DCI module and I2C module. The
WM8510SampleRate8KConfig()function configures the WM8510 codec for a
sampling rate of 8 kHz. The Wideband communication demonstration calls the
WM8510SampleRate16KConfig() function to configure the WM8510 codec for a
sampling rate of 16 kHz.
The UART2_open function configures the UART2 module on the dsPIC DSC for
operation at the baud rate specified in UART2Drv.h. It also enables the UART2
module for transmission and reception. The driver provides a synchronous interface
through the UART2Read() and UART2Write() functions. The main processing loop
uses these functions to know when a frame of data has been received and when frame
transmission has been completed.
The BoardSychronize() function is called to ensure that the two boards are
synchronized. The UART driver is checked for a full frame of encoded data. If a frame
of data has been received, the Speex8KHzDecode() function is called to decode this
frame. The decoded speech frame is written to the WM8510 codec driver. The codec
driver is polled for a frame of raw speech samples. If the frame is ready, the
Speex8KHzEncode() function is called. The encoded frame is written to the UART2
driver for transmission.
3.1.2
Playback Demonstration
The Playback demonstration shows how the dsPIC DSC Speex Speech
Encoding/Decoding Library can be used in a playback type of application where the
encoded frames are read from Flash program memory, decoded by the Speex decoder,
and then played out. By storing the Speex encoded speech frames in Flash program
memory, the application can minimize the external memory usage.
3.1.2.1
DEMONSTRATION SUMMARY
The Playback code example requires the use of one Explorer 16 Development Board
with one Audio PICtail Plus Daughter Board (not included with the software license). A
headset is connected to the Audio PICtail Plus Daughter Board. The demonstration
code reads Speex encoded frames, which are stored in Flash program memory. Every
frame is then decoded using the Speex decoder. The decoded speech data is written
to the WM8510 codec for playback on the output device, such as headphones.
The encoded speech data is obtained using the Speex PC-based Encoder Utility
(PCEU). The resulting .s file generated by the PCEU is included into the project and
compiled. The encoded speech data now becomes a part of Flash program memory.
The code example invokes Speex16KHzDecode() or Speex8KHzDecode()
function from the dsPIC DSC Speex Speech Encoding/Decoding Library to decode
speech data.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 25
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
3.1.2.2
DEMONSTRATION SETUP
The demonstration application is intended to run on the Explorer 16 Development
Board with an Audio PICtail Plus Daughter Board (not included with the software
license). The procedure described in this section applies to both the Narrowband and
the Wideband Speex Playback demonstration.
Use the procedure outlined in the following section to set up the demonstration.
3.1.2.2.1
Configure Explorer 16 Development Board and Audio PICtail Plus
Daughter Board
Before applying power, you need to configure the boards:
1. On the Audio PICtail Plus Daughter Board, set jumper J4 (O/P SEL) to the codec
position and set jumper J8 (LN/MIC) to the microphone position.
2. Insert the Audio PICtail Plus Daughter Board into the Explorer 16 Development
Board PICtail Plus socket J5.
3. Connect an output device, such as headphones, to socket J10 on the Audio
PICtail Plus Daughter Board.
4. Once the setup is complete, apply power to the Explorer 16 Development Board.
3.1.2.2.2
Programming the dsPIC DSC Device
Use this process to load the Speex Playback demonstration into the dsPIC DSC device
on the Explorer 16 Development Board:
1. On your PC, launch MPLAB IDE and open the dsPIC33F Playback
Demo.mcp project file located in the Playback folder. For more information on
using MPLAB IDE, refer to the “MPLAB® IDE, Simulator, Editor User's Guide”
(DS51025).
2. Select File > Import > dsPIC33F Playback Demo.hex to import the project
hexadecimal file.
3. Select Programmer > Connect to link the MPLAB ICD 3 to the dsPIC DSC target
device. The Output window confirms that the MPLAB ICD 3 is ready.
4. Select Programmer > Program. The Output window displays the download
process and indicates that the programming was successful.
5. Connect the MPLAB ICD 3 to the Explorer 16 Development Board.
6. Program the dsPIC DSC device on the board.
7. When the program is loaded, disconnect the MPLAB ICD 3 from the board
(remove the telephone cable from the MPLAB ICD 3 connector).
Note:
3.1.2.3
The MPLAB REAL ICE can be used in place of MPLAB ICD 3.
DEMONSTRATION PROCEDURE
After the demonstration application has been programmed into the device, the
application is now ready to run. Use the following procedure to run the demonstration.
1. Reset the board. LED D3 on the board will light up indicating that the application
is running.
2. Listen to the speech sample being played back repeatedly on the output device,
such as headphones.
DS70328B-page 26
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
3.1.2.4
DEMONSTRATION CODE DESCRIPTION
The demonstration code runs on a dsPIC DSC device, using the Primary Oscillator as
the clock source with the PLL set for 40 MIPS operation. The file, main.c, contains the
main function for the demonstration application. This main function allocates all the
variables and arrays in data memory that are needed by the WM8510 codec driver, as
well as the blocks of data memory that need to be allocated for the dsPIC DSC Speex
Speech Encoding/Decoding Library functions.
The main function calls the Speex8KHzDecoderInit() function (or the
corresponding Wideband functions for the Wideband Playback demonstration) from
the dsPIC DSC Speex Speech Encoding/Decoding Library, which initializes the Speex
decoder algorithm to its default and initial state.
The main function also calls the WM8510Init() function to initialize the DCI
module, the I2C module, the WM8510 codec and the DCI interrupt. The DCI
module acts as a Master and drives the serial clock and frame synchronization
lines. The WM8510 codec acts as a Slave. The DCI module is set for the
multi-channel Frame Sync Operating mode, with 16-bit data words and 16 data
words or time slots per frame, of which only one transmit slot and one receive slot
are used in this demonstration.
The dsPIC DSC device will send the control information to the WM8510 codec
through the dsPIC DSC device’s I2C module. Subsequently, the WM8510Start()
function is used to enable the DCI module and I2C module. The
WM8510SampleRate8KConfig() function configures the WM8510 codec for a
sampling rate of 8 kHz. The Wideband communication demonstration calls the
WM8510SampleRate16KConfig() function to configure the WM8510 codec for a
sampling rate of 16 kHz.
The PgmMemOpen() function opens a handle to Flash program memory for reading.
The main loop reads one frame from the Flash program memory using the
PgmMemRead() and passes it to the Speex8KHzDecode() function for decoding. The
decoded speech frame is written to the WM8510 codec driver for playback.
3.1.3
Record Play Demonstration
The Speex Record Play demonstration shows the use of the dsPIC DSC Speex Speech
Encoding/Decoding Library in a voice recorder type of application. The demonstration
emphasizes the reduction in memory requirement for storing speech data. This
demonstration is an example of a half-duplex system.
3.1.3.1
DEMONSTRATION SUMMARY
The Record Play demonstration code example requires the use of one Explorer 16
Development Board with one Audio PICtail Plus Daughter Board (not included with the
software license). A headset is connected to the Audio PICtail Plus Daughter Board.
In Record mode, the WM8510 codec on the Audio PICtail Plus Daughter Board will
sample and convert the speech signal captured by the microphone and provide it to the
dsPIC DSC device through the DCI module. The dsPIC DSC device will compress the
speech signal using the Speex encoder and will then store it in the serial Flash memory
available on the Audio PICtail Plus Daughter Board. In Playback mode, the application
reads the encoded speech frames stored in serial Flash data and then decodes these
frames using the Speex decoder. The decoded speech data is written to the WM8510
codec for playback on the headphones.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 27
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
For a speech signal that is sampled at 8 kHz at 16-bit resolution, the resulting data rate
is 128 kbps. To store one minute of raw speech data in memory would require 960 KB
of memory. By encoding the speech signal using a Narrowband Speex mode, such
as 8 kbps mode, the memory required to store one minute of speech is 60 KB.
The code examples invoke the Speex16KHzEncode() and Speex16KHzDecode()
functions (for Wideband), or the Speex8KHzEncode(), or the Speex8KHzDecode()
function (for Narrowband) from dsPIC DSC Speex Speech Encoding/Decoding Library
to encode and decode speech data.
3.1.3.2
DEMONSTRATION SETUP
The demonstration application is intended to run on the Explorer 16 Development
Board with an Audio PICtail Plus Daughter Board (not included with the software
license). The procedure described in this section applies to both the Narrowband and
the Wideband Speex Record Play demonstration.
Use the procedure outlined in the following section to set up the demonstration.
3.1.3.2.1
Configure Explorer 16 Development Board and Audio PICtail Plus
Daughter Board
Before applying power, you need to configure the boards:
1. On the Audio PICtail Plus Daughter Board, set jumper J4 (O/P SEL) to the codec
position and set jumper J8 (LN/MIC) to the microphone position (see Figure 3-2).
2. Insert the Audio PICtail Plus Daughter Board into the Explorer 16 Development
Board PICtail Plus socket J5.
3. Connect the headphones to socket J10 on the Audio PICtail Plus Daughter
Board.
4. Connect a microphone to socket J1 on the Audio PICtail Plus Daughter Board.
5. Once the setup is complete, apply power to the Explorer 16 Development Board.
3.1.3.2.2
Programming the dsPIC DSC Device
Use this process to load the Speex Playback demonstration into the dsPIC DSC device
on the Explorer 16 Development Board.
1. On your PC, start MPLAB IDE and open the dsPIC33F Record Play
Demo.mcp project located in the RecordPlay folder. For more information on
using MPLAB IDE, refer to the “MPLAB® IDE, Simulator, Editor User's Guide”
(DS51025).
2. Select File > Import > dsPIC33F Record Play Demo.hex to import the project file.
3. Select Programmer > Connect to link the MPLAB ICD 3 to the target dsPIC DSC
device. The Output window shows that the MPLAB ICD 3 is ready.
4. Select Programmer > Program. The Output window displays the download
process and indicates that the programming was successful.
5. Connect the MPLAB ICD 3 to the Explorer 16 Development Board.
6. Program the dsPIC DSC device on the board.
7. When the program is loaded, disconnect the MPLAB ICD 3 from the board
(remove the telephone cable from the MPLAB ICD 3 connector).
Note:
DS70328B-page 28
The MPLAB REAL ICE can be used in place of MPLAB ICD 3.
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
3.1.3.3
DEMONSTRATION PROCEDURE
After the demonstration application has been programmed into the device, the
application is now ready to run. Use the following procedure to run the demonstration
1. Reset the board. LED D3 on the board will light up indicating that the application
is running
2. Press switch S3 to start the erase and record process.
LED D4 will light up indicating the serial Flash memory is being erased. After the
erase is done, LED D4 turns off and LED D7 will switch on indicating that
recording is in progress. The microphone signal will be captured and stored in
serial Flash memory.
3. Press Switch S6. This will stop the Record mode and start the Playback mode.
LED D7 turns OFF and LED D8 lights up.
4. To start recording again, press switch S3.
3.1.3.4
DEMONSTRATION CODE DESCRIPTION
The demonstration code runs on a dsPIC DSC device, using the Primary Oscillator as
the clock source with the PLL set for 40 MIPS operation. The file, main.c, contains the
main function for the demonstration application. This main function allocates all of the
variables and arrays in data memory that are needed by the WM8510 codec driver and
the SST25VF040B serial Flash memory driver, as well as the blocks of data memory
that need to be allocated for the dsPIC DSC Speex Speech Encoding/Decoding Library
functions.
The main function calls the Speex8KHzEncoderInit() and
Speex8KHzDecoderInit() functions (or the corresponding Wideband functions for
the Wideband Record Play demonstration) from the dsPIC DSC Speex Speech
Encoding/Decoding Library, which initializes the Speex decoder algorithm to its default
and initial state.
The main function also calls the WM8510Init()function to initialize the DCI module,
the I2C module, the WM8510 codec, and the DCI interrupt. The DCI module acts as a
Master and drives the serial clock and frame synchronization lines. The WM8510
codec acts as a Slave. The DCI module is set for the multi-channel Frame Sync
Operating mode, with 16-bit data words and 16 data words or time slots per frame, of
which only one transmit slot and one receive slot are used in this demonstration.
The dsPIC DSC device will send the control information to the WM8510 code through
the dsPIC DSC device’s I2C module. Subsequently, the WM8510Start() function is
used to enable the DCI module and I2C module.
The WM8510SampleRate8KConfig() function configures the WM8510 codec for a
sampling rate of 8 kHz. The Wideband communication demonstration calls the
WM8510SampleRate16KConfig() function to configure the WM8510 codec for a
sampling rate of 16 kHz.
The SST25VF040BInit() function is called to initialize the serial Flash driver
memory. The SST25VF040BStart() function enables the dsPIC DSC device’s SPI
module, which communicates with the serial Flash.
The main function polls the switches to determine if Record mode or Playback mode is
selected. If Record mode is selected, the SST25VF040BIOCtl() function is called
with the chip erase command. When the chip erase is complete, the current speech
frame is encoded using the Speex8KHzEncode() function and written to Flash
program memory using the SST25VF040BWrite() function. The speech frame is
also provided to the WM8510 driver for output. If the Playback mode is selected, the
serial Flash memory is read using the SST25VF040BRead() function, decoded using
the Speex8KHzDecode() function, and written to the WM8510 driver for output.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 29
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
3.2
QUICK START DEMONSTRATION FOR dsPIC33E DEVICE FAMILY
The following demonstration examples are covered in this section:
• Communication Demonstration
• Playback Demonstration
• Record Play Demonstration
3.2.1
Communication Demonstration
The Communication demonstration shows how the dsPIC DSC Speex Speech
Encoding/Decoding Library can be used to reduce the required bandwidth in a
full-duplex communication type of application running on a dsPIC33E device.
3.2.1.1
DEMONSTRATION SUMMARY
The Communication Code example requires the use of two MEBs with two dsPIC33E
USB Starter Kits (not included with the software license), which are set up as shown in
Figure 3-4.
FIGURE 3-4:
SPEEX COMMUNICATION DEMONSTRATION SETUP
MEB with dsPIC33E USB Starter Kit running
Speex Speech Encoding/Decoding Library
Multimedia Expansion Board (MEB)
with dsPIC33E USB Starter Kit running
Speex Speech Encoding/Decoding Library
22
20
22
20
J5
J5
SOUT
SOUT
Board 1
Board 2
Headsets are connected to the MEBs. When a user speaks into the headset connected
to board 1, the WM8731 codec on the MEB will sample and convert the data, and
provide it to the dsPIC DSC device through the DCI module. The dsPIC DSC device
will compress the speech signal using the Speex encoder and then transmit the
compressed speech frame data through the UART2 module and the I/O expansion
connector to board 2.
The dsPIC DSC device on board 2 receives the encoded frame through the on-board
I/O expansion connector and the device’s UART2 module. The dsPIC DSC device
decodes the received frame using the Speex decoder, and then outputs the signal on
the headset through its DCI module and the on-board WM8731 codec.
For a speech signal that is sampled at 8 kHz at 16-bit resolution, the resulting data rate
is 128 kbps. To communicate this data to a remote terminal over a communication link,
the minimum required communication link bandwidth would be 128 kbps. By encoding
the speech signal using a Narrowband Speex mode, for example, for 8 kbps mode, the
minimum communication link bandwidth would be 8 kbps. This results in a bandwidth
reduction of 16x.
The code examples invoke the Speex16KHzEncode() and Speex16KHzDecode()
functions (for Wideband) or Speex8KHzEncode()or Speex8KHzDecode()
function (for Narrowband) from dsPIC DSC Speex Speech Encoding/Decoding Library
to encode and decode speech data.
DS70328B-page 30
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
3.2.1.2
DEMONSTRATION SETUP
The demonstration application is intended to run on the MEB with a dsPIC33E USB
Starter Kit (not included with the software license). The procedure described in this
section applies to both the Narrowband and the Wideband Speex communication
demonstration.
Use the procedure outlined in the following section to set up the demonstration.
3.2.1.2.1
Configure MEBs and dsPIC33E USB Starter Kits
Before applying power, you need to configure the boards:
1. Insert a dsPIC33E USB Starter Kit into the starter kit connector on the MEB 1.
2. Connect the dsPIC33E USB Starter Kit to a PC using the USB A-to-mini-B cable
provided with the starter kit.
3. Connect headphones to MEB 1.
4. Connect a microphone to MEB 1.
5. Repeat steps 1 through 4 for the second dsPIC33E USB Starter Kit and MEB.
6. Using a single-strand wire, connect pin 20 of the I/O expansion connector on
MEB 1 to pin 22 of the I/O expansion connector on MEB 2.
7. Using another single-strand wire, connect pin 22 of the I/O expansion connector
on MEB 1 to pin 20 of the I/O expansion connector on MEB 2.
3.2.1.2.2
Programming the dsPIC DSC Device
Use this process to load the Speex communication demonstration into the dsPIC DSC
device on the MEB.
1. On your PC, start MPLAB IDE and open the dsPIC33F Communication
Demo.mcp project located in the Communication folder. For more information
on using MPLAB IDE, refer to the “MPLAB® IDE, Simulator, Editor User's Guide”
(DS51025).
2. Select File > Import > dsPIC33E Communication Demo 1.hex to import the
project hexadecimal file for board 1, or select File > Import > dsPIC33E
Communication Demo 2.hex to import the project hexadecimal file for board 2.
3. Select Programmer > Starter Kit on Board as the programmer, and then select
Programmer > Connect to link to the dsPIC DSC target device. The Output
window confirms that the target device is ready.
4. Select Programmer > Program. The Output window displays the download
process and indicates that the programming was successful.
Note:
After programming, unplug and reconnect the USB cable to the starter kit,
to ensure that the WM8731 audio codec can be reconfigured.
5. Repeat steps 2 through 4 for the second board.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 31
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
3.2.1.3
DEMONSTRATION PROCEDURE
After the demonstration application has been programmed into both devices, the
application is now ready to run. Use the following procedure to run the demonstration.
1. Using the MPLAB IDE, reset board 1. LED D1 on the board will light up indicating
that the board is waiting for synchronization to be complete.
2. Using the MPLAB IDE programmer, reset board 2. LED D2 on both of the boards
will light up indicating that the boards are synchronized and communicating
encoded speech data frames.
3. Speak into the microphone connected to board 1. This speech will be heard in
the output device, such as headphones, connected to board 2 and vice-versa.
Note:
3.2.1.4
If only one PC is available for running the demonstration, then program
board 2. Disconnect the USB cable from board 2 after programming, and
use an external 9V power supply to reset and run board 2 (after the
program in board 1 is already running).
DEMONSTRATION CODE DESCRIPTION
The demonstration code runs on a dsPIC DSC device by using the Primary Oscillator
as the clock source with the PLL set for 40 MIPS operation. The file, main.c, contains
the main function for the demonstration application. This main function allocates all of
the variables and arrays in data memory that are needed by the UART and WM8731
codec driver, as well as the blocks of data memory that need to be allocated for the
dsPIC DSC Speex Speech Encoding/Decoding Library functions.
The main function calls the Speex8KHzEncoderInit()and
Speex8KHzDecoderInit() functions (or the corresponding Wideband functions for
the Wideband communication demonstration) from the dsPIC DSC Speex Speech
Encoding/Decoding Library, which initializes the Speex encoder and decoder
algorithms to their default and initial state.
The main function also calls the WM8731Init()function to initialize the DCI module,
the I2C module, the WM8731 codec and the DCI interrupt. The WM8731 codec acts as
a Master and drives the serial clock and frame synchronization lines. The DCI module
is set for the multi-channel Frame Sync Operating mode, with 16-bit data words and
two data words or time slots per frame, that is, only one transmit slot and one receive
slot are used in this demonstration.
The dsPIC DSC device will send the control information to the WM8731 codec
through the I2C module of the dsPIC DSC device. Subsequently, the
WM8731Start()function is used to enable the DCI module and I2C module. The
initialization code configures the WM8731 codec for a sampling rate of 8 kHz in
case of Narrowband mode, and a sampling rate of 16 kHz in case of Wideband
mode.
The UART2_open function configures the UART2 module on the dsPIC DSC for
operation at the baud rate specified in UART2Drv.h. It also enables the UART2
module for transmission and reception. The driver provides a synchronous interface
through the UART2Read() and UART2Write() functions. The main processing loop
uses these functions to know when a frame of data has been received and when frame
transmission has been completed.
The BoardSychronize() function is called to ensure that the two boards are
synchronized. The UART driver is checked for a full frame of encoded data. If a frame
of data has been received, the Speex8KHzDecode() function is called to decode this
frame. The decoded speech frame is written to the WM8731 codec driver. The codec
driver is polled for a frame of raw speech samples. If the frame is ready, the
Speex8KHzEncode() function is called. The encoded frame is written to the UART2
driver for transmission.
DS70328B-page 32
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
3.2.2
Playback Demonstration
The Playback demonstration shows how the dsPIC DSC Speex Speech
Encoding/Decoding Library can be used in a playback type of application where
encoded frames are read from Flash program memory, decoded by the Speex decoder,
and then played out. By storing Speex encoded speech frames in Flash program
memory, the application can minimize the external memory usage.
3.2.2.1
DEMONSTRATION SUMMARY
The Playback code example requires the use of one MEB with one dsPIC33E USB
Starter Kit (not included with the software license). A headset is connected to the Audio
PICtail Plus Daughter Board. The demonstration code reads the Speex encoded
frames, which are stored in Flash program memory. Every frame is then decoded using
the Speex decoder. The decoded speech data is written to the WM8731 codec for
playback on the headphones.
The encoded speech data is obtained using the Speex PCEU. The resulting .s file
generated by the PCEU is included into the project and compiled. The encoded speech
data now becomes a part of Flash program memory.
The code example invokes Speex16KHzDecode() or Speex8KHzDecode()
function from the dsPIC DSC Speex Speech Encoding/Decoding Library to decode
speech data.
3.2.2.2
DEMONSTRATION SETUP
The demonstration application is intended to run on the MEB with a dsPIC33E USB
Starter Kit (not included with the software license). The procedure described in this
section applies to both the Narrowband and the Wideband Speex Playback
demonstration. Use the procedure outlined in the following section to set up the
demonstration.
3.2.2.2.1
Configure MEB and dsPIC33E USB Starter Kit
Before applying power, you need to configure the boards:
1. Insert a dsPIC33E USB Starter Kit into the starter kit connector on the MEB.
2. Connect the dsPIC33E USB Starter Kit to a PC using the USB A-to-mini-B cable
provided with the Starter Kit
3. Connect an output device, such as headphones, to the MEB.
3.2.2.2.2
Programming the dsPIC DSC Device
Use this process to load the Speex Playback demonstration into the dsPIC DSC device
on the Explorer 16 Development Board:
1. On your PC, launch MPLAB IDE and open the dsPIC33E Playback
Demo.mcp project file located in the Playback folder. For more information on
using MPLAB IDE, refer to the “MPLAB® IDE, Simulator, Editor User's Guide”
(DS51025).
2. Select File > Import > dsPIC33E Playback Demo.hex to import the project
hexadecimal file.
3. Select Programmer > Starter Kit on Board as the Programmer and then select
Programmer > Connect to link to the dsPIC DSC target device. The Output
window confirms that the target device is ready.
4. Select Programmer > Program. The Output window displays the download
process and indicates that the programming was successful.
Note:
After programming, unplug and reconnect the USB cable to the starter kit,
to ensure that the WM8731 audio codec can be reconfigured.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 33
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
3.2.2.3
DEMONSTRATION PROCEDURE
After the demonstration application has been programmed into the device, the
application is now ready to run. Use the following procedure to run the demonstration.
1. Using the MPLAB IDE, reset and run the board.
2. Listen to the speech sample being played back repeatedly on the output device,
such as headphones.
3.2.2.4
DEMONSTRATION CODE DESCRIPTION
The demonstration code runs on a dsPIC DSC device, using the Primary Oscillator as
the clock source with the PLL set for 40 MIPS operation.
The file, main.c, contains the main function for the demonstration application. This
main function allocates all the variables and arrays in data memory that are needed by
the WM8731 codec driver, as well as the blocks of data memory that need to be
allocated for the dsPIC DSC Speex Speech Encoding/Decoding Library functions.
The main function calls the Speex8KHzDecoderInit() function (or the
corresponding Wideband functions for the Wideband Playback demonstration) from
the dsPIC DSC Speex Speech Encoding/Decoding Library, which initializes the Speex
decoder algorithm to its default and initial state.
The main function also calls the WM8731Init() function to initialize the DCI
module, the I2C module, the WM8731 codec and the DCI interrupt. The WM8731
codec acts as a Master and drives the serial clock and frame synchronization lines.
The DCI module is set for the multi-channel Frame Sync Operating mode, with
16-bit data words and two data words or time slots per frame (that is, only one
transmit slot and one receive slot are used in this demonstration). The dsPIC DSC
device will send the control information to the WM8731 codec through the dsPIC
DSC device’s I2C module. Subsequently, the WM8731Start() function is used to
enable the DCI module and I2C module. The initialization code configures the
WM8731 codec for a sampling rate of 8 kHz in case of Narrowband mode, and a
sampling rate of 16 kHz in case of Wideband mode.
The PgmMemOpen() function opens a handle to the Flash program memory for
reading. The main loop reads one frame from the Flash program memory using the
PgmMemRead() and passes it to the Speex8KHzDecode() function for decoding. The
decoded speech frame is written to the WM8731 codec driver for playback.
3.2.3
Record Play Demonstration
The Speex Record Play demonstration shows the use of the dsPIC DSC Speex Speech
Encoding/Decoding Library in a voice recorder type of application. The demonstration
emphasizes the reduction in memory requirement for storing speech data. This
demonstration is an example of a half-duplex system.
3.2.3.1
DEMONSTRATION SUMMARY
The Record Play demonstration code example requires the use of one Explorer 16
Development Board with one Audio PICtail Plus Daughter Board (not included with the
software license). A headset is connected to the Audio PICtail Plus Daughter Board.
In Record mode, the WM8731 codec on the Audio PICtail Plus Daughter Board will
sample and convert the speech signal captured by the microphone and provide it to the
dsPIC DSC device through the DCI module. The dsPIC DSC device will compress the
speech signal using the Speex encoder and will then store it in the serial Flash memory
available on the Audio PICtail Plus Daughter Board. In Playback mode, the application
reads the encoded speech frames stored in serial Flash data and then decodes these
frames using the Speex decoder. The decoded speech data is written to the WM8731
codec for playback on the headphones.
DS70328B-page 34
© 2008-2011 Microchip Technology Inc.
Quick Start Demonstration
For a speech signal that is sampled at 8 kHz at 16-bit resolution, the resulting data rate
is 128 kbps. To store one minute of raw speech data in memory would require 960 KB
of memory. By encoding the speech signal using a Narrowband Speex mode, such
as 8 kbps mode, the memory required to store one minute of speech is 60 KB.
The code examples invokes the Speex16KHzEncode() and Speex16KHzDecode()
functions (for Wideband) or the Speex8KHzEncode()or Speex8KHzDecode()
function (for Narrowband) from dsPIC DSC Speex Speech Encoding/Decoding Library
to encode and decode speech data.
3.2.3.2
DEMONSTRATION SETUP
The demonstration application is intended to run on the MEB with a dsPIC33E USB
Starter Kit (not included with the software license). The procedure described in this
section applies to both the Narrowband and the Wideband Speex Record Play
demonstration. Use the procedure outlined in the following section to set up the
demonstration.
3.2.3.2.1
Configure MEB and dsPIC33E USB Starter Kit
Before applying power, you need to configure the boards:
1. Insert a dsPIC33E USB Starter Kit into the starter kit connector on the MEB.
2. Connect the dsPIC33E USB Starter Kit to a PC using the USB A-to-mini-B cable
provided with the Starter Kit
3. Connect an output device, such as headphones, to the MEB.
3.2.3.2.2
Programming the dsPIC DSC Device
Use this process to load the Speex Playback demonstration into the dsPIC DSC device
on the Explorer 16 Development Board:
1. On your PC, launch MPLAB IDE and open the dsPIC33E Record Play
Demo.mcp project file located in the Playback folder. For more information on
using MPLAB IDE, refer to the “MPLAB® IDE, Simulator, Editor User's Guide”
(DS51025).
2. Select File > Import > dsPIC33E Record Play Demo.hex, to import the project
hexadecimal file.
3. Select Programmer > Starter Kit on Board as the Programmer, and then select
Programmer > Connect to link to the dsPIC DSC target device. The Output
window confirms that the target device is ready.
4. Select Programmer > Program. The Output window displays the download
process and indicates that the programming was successful.
Note:
3.2.3.3
After programming, unplug and reconnect the USB cable to the starter kit,
to ensure that the WM8731 audio codec can be reconfigured.
DEMONSTRATION PROCEDURE
After the demonstration application has been programmed into the device, the
application is now ready to run. Use the following procedure to run the demonstration
1. Using the MPLAB IDE, reset and run the board.
2. Press switch S1 for a few seconds, to start the erase and record process.
Release the switch when LED D1 lights up indicating the serial Flash memory is
being erased. After the erase is done, LED D1 turns OFF and LED D2 will switch
ON indicating that recording is in progress. The microphone signal will be
captured and stored in serial Flash memory.
3. Press switch S1 again for a few seconds. This will stop the Record mode and
start the Playback mode. LED D2 turns OFF and LED D3 lights up.
4. To start recording again, press switch S1 again, as described in step 2.
© 2008-2011 Microchip Technology Inc.
DS70328B-page 35
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
3.2.3.4
DEMONSTRATION CODE DESCRIPTION
The demonstration code runs on a dsPIC DSC device, using Primary Oscillator as the
clock source with the PLL set for 40 MIPS operation. The file, main.c, contains the
main function for the demonstration application. This main function allocates all of the
variables and arrays in data memory that are needed by the WM8731 codec driver and
the SST25VF016B serial Flash memory driver, as well as the blocks of data memory
that need to be allocated for the dsPIC DSC Speex Speech Encoding/Decoding Library
functions.
The main function calls the Speex8KHzEncoderInit() and
Speex8KHzDecoderInit() functions (or the corresponding Wideband functions for
the Wideband Record Play demonstration) from the dsPIC DSC Speex Speech
Encoding/Decoding Library, which initializes the Speex decoder algorithm to its default
and initial state.
The main function also calls the WM8731Init()function to initialize the DCI module,
the I2C module, the WM8731 codec and the DCI interrupt. The WM8731 codec acts as
a Master and drives the serial clock and frame synchronization lines. The DCI module
is set for the multi-channel Frame Sync Operating mode, with 16-bit data words and
two data words or time slots per frame (that is, transmit slots and two receive slots are
used in this demonstration). The dsPIC DSC device will send the control information to
the WM8731 codec through the dsPIC DSC device’s I2C module. Subsequently, the
WM8731Start() function is used to enable the DCI module and I2C module.
The initialization code configures the WM8731 codec for a sampling rate of 8 kHz in the
case of Narrowband mode and a sampling rate of 16 kHz in the case of Wideband
mode.
The SST25VF016BInit() function is called to initialize the serial Flash driver
memory. The SST25VF016BStart() function enables the dsPIC DSC device’s SPI
module, which communicates with the serial Flash.
The main function polls the switches to determine if Record mode or Playback mode is
selected. If Record mode is selected, the SST25VF016BIOCtl() function is called
with the chip erase command. When the chip erase is complete, the current speech
frame is encoded using the Speex8KHzEncode() function and written to Flash
program memory using the SST25VF016BWrite() function. The speech frame is
also provided to the WM8731 driver for output. If the Playback mode is selected, the
serial Flash memory is read using the SST25VF016BRead() function, decoded using
the Speex8KHzDecode() function, and written to the WM8731 driver for output.
DS70328B-page 36
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Chapter 4. Application Programming Interface
This chapter describes in detail the Application Programming Interface (API) functions
that are available to the dsPIC DSC Speex Speech Encoding/Decoding Library.
The following topics are covered in this chapter:
•
•
•
•
•
•
•
•
•
4.1
Adding the Library to an Application
Memory Model Compile Options
Using the Library
Register Usage
Packet Loss and Corruption
PC Encoder Utility (PCEU) Output Files
Resource Requirements
API Functions
Application Tips
ADDING THE LIBRARY TO AN APPLICATION
To use the dsPIC DSC Speex Speech Encoding/Decoding Library in an application, the
library archive must be added to the application project workspace. The applicable
include .h file must be included in the application code. Consider the following when
adding the library files to an application:
• If the application only requires the 8 kHz sampling rate speech coding
(Narrowband) functions with an output data rate of 8 kbps, the files
libspeex_8k_33F.a or libspeex_8k_33E.a, and speek_8k.h can be
included into the application
• If the application requires a 16 kHz sampling rate with support for multiple modes,
the files, libspeex_33F.a or libspeex_33E.a, and speex.h must be
included in the application
The procedure for adding the Wideband Speex Library archive to the project is shown
below. Note that the procedure for adding the Narrowband Speex Library archive is
similar, the file selected would then be libspeex_8k.a. The libspeex.a library
archive also supports two Narrowband modes.
Use the following procedure to add the library to the application:
1. In the application, MPLAB workspace, right-click Library Files in the Project
Window and select Add files.
2. Browse to the location of the desired speex library archive (available in the libs
folder in the installation directory).
3. Select the desired file, and then click Open. The library is now added to the
application.
To use the library functions, include the speex.h file, in the application source code.
This file can be copied from the h folder (located in the installation directory) to the
application project folder.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 37
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
4.2
MEMORY MODEL COMPILE OPTIONS
While using any of the Speex library archive files in an application, the compiler should be
directed to use a large memory model, as described in the following steps:
1. From the MPLAB IDE menu, select Project > Build Options > Project.
2. Click the MPLAB C30 tab and set the following options:
a) From the Categories drop-down list, select Memory Model, as shown in
Figure 4-1.
FIGURE 4-1:
PROJECT BUILD OPTIONS
b) In the Data Model section, select Large data model, as shown in Figure 4-2.
DS70328C-page 38
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
FIGURE 4-2:
COMPILER MEMORY MODEL SETTINGS
3. Click Apply, and then click OK. This completes the procedure.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 39
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
4.3
USING THE LIBRARY
The dsPIC DSC Speex Speech Encoding/Decoding Library has been designed to be
usable in a re-entrant environment. This enables the algorithm to process multiple
channels of audio. Since the encoder and the decoder algorithms operate
independently of each other, an application does not have to instantiate a decoder or
encoder if it is not needed. Multiple encoders can share scratch memories. Multiple
decoders can share scratch memories. The coding steps required to use the
Narrowband Speex Library and Wideband Speex Library are described below.
4.3.1
Narrowband Speex Coding Steps
To use Narrowband Speex, the application must include libspeex_8k_33F.a or
libspeex_8k_33E.a into the project and include speex_8k.h in the application
code. The following coding steps must then be performed. Refer to Example 4-1 for the
actual code required.
1. Allocate the memory for the Narrowband Speex Encoder. This memory is an
integer array of size NB_SPEEX_ENCODER_STATE_SIZE. Every audio channel
must have its own encoder state holder.
2. Allocate the memory for the Narrowband Speex Decoder. This memory is an
integer array of size NB_SPEEX_DECODER_STATE_SIZE. Every audio channel
must have its own decoder state holder
3. Allocate Encoder X and Y Scratch Memories. The Encoder X scratch memory is
an unsigned character array of size NB_SPEEX_ENCODER_X_SCRATCH_SIZE
and is placed in X memory aligned on an address boundary of 2 bytes. The
Encoder Y scratch memory is an unsigned character array of size
NB_SPEEX_ENCODER_Y_SCRATCH_SIZE and is placed in Y memory aligned on
an address boundary of 2 bytes. Multiple encoders can share scratch memories.
4. Allocate the Decoder X and Y Scratch Memories. The Decoder X scratch
memory is an unsigned character array of size
NB_SPEEX_DECODER_X_SCRATCH_SIZE and is placed in X memory aligned on
an address boundary of 2 bytes. The Decoder Y scratch memory is an unsigned
character array of size NB_SPEEX_DECODER_Y_SCRATCH_SIZE and is placed
in Y memory aligned on an address boundary of 2 bytes. Multiple decoders can
share scratch memories.
Note:
In some dsPIC33E devices, the Y memory is located in the Extended Data
Space (EDS). In such cases, the Y scratch memory array must be tagged
with the __eds__ keyword and assigned an EDS attribute.
5. Initialize the Encoder for each audio channel. Use the
Speex8KHzEncoderInit() function to initialize the Narrowband Speex
encoder state for each audio channel.
6. Initialize the Decoder for each audio channel. Use the
Speex8KHzDecoderInit() function to initialize the Narrowband Speex
decoder state for each audio channel.
7. Encode a raw speech data frame. Use the Speex8KHzEncode() function to
encode a frame of raw speech. Note that the size of the frame must be
NB_SPEEX_ENCODER_INPUT_SIZE.
8. Decode a encoded speech data frame. Use the Speex8KHzDecode() function
to encode a frame of encoded speech. Note that the size of the frame must be
NB_SPEEX_DECODER_INPUT_SIZE_8K.
DS70328C-page 40
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
EXAMPLE 4-1:
NARROWBAND SPEEX LIBRARY CODE SNIPPET
#include “speex_8k.h”
.
.
.
int encoder[NB_SPEEX_ENCODER_STATE_SIZE];
int decoder[NB_SPEEX_DECODER_STATE_SIZE];
/* Step 1 */
/* Step 2 */
unsigned char encXScratchMem[NB_SPEEX_ENCODER_X_SCRATCH_SIZE]; _XBSS(2); /* Step 3
unsigned char encYScratchMem[NB_SPEEX_ENCODER_Y_SCRATCH_SIZE]; _YBSS(2); /* Step 3
unsigned char decXScratchMem[NB_SPEEX_DECODER_X_SCRATCH_SIZE]; _XBSS(2); /* Step 4
unsigned char decYScratchMem[NB_SPEEX_DECODER_Y_SCRATCH_SIZE]; _YBSS(2); /* Step 4
.
.
.
Speex8KHzEncoderInit(encoder, encXScratchMem, encYScratchMem, NB_SPEEX_BITRATE_8K,
SPEEX_NORMAL_PITCH);
/* Step 5
Speex8KHzDecoderInit(decoder, decXScratchMem, decYScratchMem);
/* Step 6
.
.
.
Speex8KHzEncode(encoder, rawSamples, encodedFrame);
/* Step 7
Speex8KHzDecode(decoder, encodedFrame, rawSamples);
/* Step 8
4.3.2
*/
*/
*/
*/
*/
*/
*/
*/
Wideband Speex Coding Steps
To use Wideband Speex, the application must include libspeex_33F.a or
libspeex_33E.a into the project and include speex.h in the application code. The
following coding steps must then be performed. Refer to Example 4-2 for the actual
code required.
1. Allocate the memory for the Wideband Speex Encoder. This memory is an
integer array of size WB_SPEEX_ENCODER_STATE_SIZE. Every audio channel
must have its own encoder state holder.
2. Allocate the memory for the Wideband Speex Decoder. This memory is an
integer array of size WB_SPEEX_DECODER_STATE_SIZE. Every audio channel
must have its own decoder state holder.
3. Allocate Encoder X and Y Scratch Memories. The Encoder X scratch memory is
an unsigned character array of size WB_SPEEX_ENCODER_X_SCRATCH_SIZE
and is placed in X memory aligned on an address boundary of 2 bytes. The
Encoder Y scratch memory is an unsigned character array of size
WB_SPEEX_ENCODER_Y_SCRATCH_SIZE and is placed in Y memory aligned on
an address boundary of 2 bytes. Multiple encoders can share scratch memories.
4. Allocate the Decoder X and Y Scratch Memories. The Decoder X scratch
memory is an unsigned character array of size
WB_SPEEX_DECODER_X_SCRATCH_SIZE and is placed in X memory aligned on
an address boundary of 2 bytes. The Decoder Y scratch memory is an unsigned
character array of size WB_SPEEX_DECODER_Y_SCRATCH_SIZE and is placed
in Y memory aligned on an address boundary of 2 bytes. Multiple decoders can
share scratch memories.
Note:
In some dsPIC33E devices, the Y memory is located in the Extended Data
Space (EDS). In such cases, the Y scratch memory array must be tagged
with the __eds__ keyword and assigned an EDS attribute.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 41
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
5. Initialize the Encoder for each audio channel. Use the
Speex16KHzEncoderInit() function to initialize the Wideband Speex
encoder state for each audio channel.
6. Initialize the Decoder for each audio channel. Use the
Speex16KHzDecoderInit() function to initialize the Wideband Speex
decoder state for each audio channel.
7. Encode a raw speech data frame. Use the Speex16KHzEncode() function to
encode a frame of raw speech. Note that the size of the frame must be
WB_SPEEX_ENCODER_INPUT_SIZE words.
8. Decode a encoded speech data frame. Use the Speex16KHzDecode()
function to encode a frame of encoded speech. Depending on the selected
mode, the size of the input array is either
WB_SPEEX_DECODER_INPUT_SIZE_9K8 or
WB_SPEEX_DECODER_INPUT_SIZE_12K8 bytes.
EXAMPLE 4-2:
WIDEBAND SPEEX LIBRARY CODE SNIPPET
#include “speex.h”
.
.
.
int encoder[WB_SPEEX_ENCODER_STATE_SIZE];
int decoder[WB_SPEEX_DECODER_STATE_SIZE];
/* Step 1 */
/* Step 2 */
unsigned char encXScratchMem[WB_SPEEX_ENCODER_X_SCRATCH_SIZE]; _XBSS(2); /* Step 3 */
unsigned char encYScratchMem[WB_SPEEX_ENCODER_Y_SCRATCH_SIZE]; _YBSS(2); /* Step 3 */
unsigned char decXScratchMem[WB_SPEEX_DECODER_X_SCRATCH_SIZE]; _XBSS(2); /* Step 4 */
unsigned char decYScratchMem[WB_SPEEX_DECODER_Y_SCRATCH_SIZE]; _YBSS(2); /* Step 4 */
.
.
.
Speex16KHzEncoderInit(encoder, encXScratchMem, encYScratchMem, WB_SPEEX_BITRATE_9K8,
SPEEX_NORMAL_PITCH);
/* Step 5 */
Speex16KHzDecoderInit(decoder, decXScratchMem, decYScratchMem);
/* Step 6 */
.
.
.
Speex16KHzEncode(encoder, rawSamples, encodedFrame);
/* Step 7 */
Speex16KHzDecode(decoder, encodedFrame, rawSamples);
/* Step 8 */
DS70328C-page 42
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
4.4
REGISTER USAGE
The dsPIC DSC Speex Speech Encoding/Decoding Library uses and modifies the
MODCON, CORCON, XMODSRT, XMODEND, YMODSRT, YMODEND and PSVPAG
registers. These registers are saved and restored to their original values after the
library has used them. If these registers are modified by the application in an Interrupt
Service Routine (ISR), the application must save and restore these registers while
entering and exiting the ISR. This will prevent the ISR from corrupting the execution
context, if the interrupt has occurred when a library function is executing.
4.5
PACKET LOSS AND CORRUPTION
The Speex algorithm robustly handles lost packets but not corrupted ones. If the
encoded packet uses an invalid mode, the decoder function will return an error code
and will try to guess the correct signal. A corrupted packet (a packet that contains
invalid vocoder data) could cause unpredictable decoder behavior. It is advisable in
such applications to implement a higher layer error checking and correction function to
ensure the integrity of the Speex packet.
4.6
PC ENCODER UTILITY (PCEU) OUTPUT FILES
The Speex PCEU generates three output files after encoding a Wave file or speech
captured through the microphone. These are described in Table 4-1.
TABLE 4-1:
DESCRIPTION OF FILES GENERATED BY PCEU
File Type
Description
.s
File containing Speex encoded data with attributes to make the data a part of
the Flash program memory on the dsPIC DSC device. This file can be added to
an application project.
.spx
File containing Speex encoded data.
.raw
File containing raw audio data.
The .s file generated by the PCEU can be included in the application workspace. After
compilation, the encoded speech data now becomes a part of the Flash program
memory. Consider the case of Speex encoded file encoded at a Wideband mode of
9.8 kbps. In this mode, each encoded frame has 25 bytes of data. Example 4-3 shows
the starting portion of the .s file generated by the PCEU for this mode.
EXAMPLE 4-3:
.S FILE FOR 9.8 kbps WIDEBAND MODE
/**********************************************************************/
/*
Speech Encoder Utility settings:
*/
/*
Input Source:
Microphone
*/
/*
Output Array:
speex_data
*/
/*
Array Size:
2502 bytes
*/
/*
Target Memory: Program Memory
*/
/*
Bitrate:
9.8 kbps
*/
/**********************************************************************/
/* There are 834 elements in the data array. */
/* Data file for storing 24-bit constants in program memory */
.global _speex_data
.section .speex, “x”
_speex_data:
.pword 0x84DD1D,
0x390030,
.pword 0x930EAB,
0x0000B6,
.pword 0xC3A32A,
0x2EE149,
© 2008-2011 Microchip Technology Inc.
0x0070CE,
0xC41D07,
0x2B252B,
0x38E71C, 0x762E00,
0x3C0601, 0x730BE4,
0x89B693, 0x1D97C8,
0x141C14
0x8530D8
0xFBC2DE
DS70328C-page 43
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
To optimize memory usage, the encoder utility will use all 24 bits (3 bytes) of one
program word to store data. Hence the first byte of the frame is stored at the low
program word. The second byte is stored at the high program byte and the third byte
of the frame is stored at the upper program byte. With reference to Example 4-3:
• 0x1D – First Byte of frame stored at low program byte
• 0xDD – Second Byte of Frame stored at high program byte
• 0x84 – Third Byte of Frame stored at upper program byte
The application program must use the TBLRD instructions to access the encoded data
in Flash program memory since the upper program byte of the program word contains
valid frame data and needs to be read.
4.7
RESOURCE REQUIREMENTS
The resource requirements for running the dsPIC DSC Speex Speech Encoding/Decoding
Library depends on which library is selected, either the Narrowband-only version
(libspeex_8k_33F.a and speex_8k.h) or the Wideband and Narrowband version
(libspeex_33F.a and speex.h). The resource requirements for each of these
versions are provided in the following sections and tables.
4.7.1
Narrowband-Only Library
The Narrowband-Only version supports one mode: 8 kbps at 8 kHz sampling rate. The
resource requirements for this library are as follows:
TABLE 4-2:
PROGRAM MEMORY USAGE
Resource
Encoder and Decoder
TABLE 4-3:
Section
.text and .const
REQUIRED INPUT AND OUTPUT BUFFERS
Resource
Size in Bytes
Alignment
Section
Encoder Input Buffer
320
2
X data memory
Encoder Output Buffer
(8 kbps mode)
20
2
X data memory
Decoder Output Buffer
320
2
X data memory
Note:
The Decoder Output Buffer is not required as the Encoder Input Buffer is
reused by the Decoder for output.
TABLE 4-4:
STATE AND SCRATCH MEMORIES
Resource
Size in Bytes
Alignment
Section
Encoder State Memory
1642
2
X data memory
Decoder State Memory
1394
2
X data memory
Encoder Scratch X Memory
800
2
X data memory
Encoder Scratch Y Memory
1500
2
Y data memory
Decoder Scratch X Memory
82
2
X data memory
Decoder Scratch Y Memory
850
2
Y data memory
TABLE 4-5:
DS70328C-page 44
Size in Bytes
29712 (dsPIC30F/dsPIC33F)
30657 (dsPIC33E)
TABLES AND CONSTANTS IN RAM
Resource
Size in Bytes
Alignment
Section
Encoder and Decoder
122 (dsPIC30F/dsPIC33F)
2606 (dsPIC33E)
2
X data memory
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
TABLE 4-6:
MIPS
Function
MIPS
Typical Call Frequency
Speex8KHzEncoderInit()
0.01
Once
Speex8KHzDecoderInit()
0.02
Once
Speex8KHzEncode()
17.8 (dsPIC30F/dsPIC33F)
22.8 (dsPIC33E)
20 ms
Speex8KHzDecode()
2.1 (dsPIC30F/dsPIC33F)
2.7 (dsPIC33E)
20 ms
TABLE 4-7:
DATA FORMAT
I/O Type
Data Type
Encoder Input
16-bit linear Pulse Code Modulation (PCM) data
Decoder Output
4.7.2
16-bit linear PCM data
Wideband and Narrowband Speex
The Wideband and Narrowband version supports the following modes:
•
•
•
•
8 kbps at 8 kHz sampling rate
11 kbps at 8 kHz sampling rate
9.8 kbps at 16 kHz sampling rate
12.8 kbps at 16 kHz sampling rate
The resource requirements for this library are as follows:
TABLE 4-8:
PROGRAM MEMORY USAGE
Resource
Size in Bytes
Section
Wideband Encoder and Wideband Decoder 38685 (dsPIC33F)
32289 (dsPIC33E)
.text and .const
Narrowband Encoder and Narrowband
Decoder
.text and .const
TABLE 4-9:
38706 (dsPIC33F)
32289 (dsPIC33E)
REQUIRED INPUT AND OUTPUT BUFFERS
Resource
Size in Bytes
Alignment
Section
Wideband Encoder Input Buffer
640
2
X data memory
Narrowband Encoder Input Buffer
320
2
X data memory
Encoder Output Buffer
(8 kbps mode)
20
2
X data memory
Encoder Output Buffer
(11 kbps mode)
28
2
X data memory
Encoder Output Buffer
(9.8 kbps mode)
25
2
X data memory
Encoder Output Buffer
(12.8 kbps mode)
32
2
X data memory
Narrowband Decoder Output Buffer
320
2
X data memory
Wideband Decoder Output Buffer
640
2
X data memory
Note:
The Decoder Output Buffer is not required, if the Encoder Input Buffer is
reused by the Decoder for output.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 45
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
TABLE 4-10:
STATE AND SCRATCH MEMORIES
Resource
Size in Bytes
Alignment
Section
Narrowband Encoder State Memory
1642
2
X data memory
Narrowband Decoder State Memory
1394
2
Y data memory
Wideband Encoder State Memory
2168
2
X data memory
Wideband Decoder State Memory
1844
2
Y data memory
Encoder Scratch X Memory
800
2
X data memory
Encoder Scratch Y Memory
2700
2
Y data memory
Decoder Scratch X Memory
82
2
X data memory
Decoder Scratch Y Memory
850
2
Y data memory
TABLE 4-11:
TABLES AND CONSTANTS IN RAM
Resource
Size in Bytes
Alignment
Section
Wideband Encoder and Wideband
Decoder
2810 (dsPIC33F)
714 (dsPIC33F)
2
X data memory
2
Y data memory
Wideband Encoder and Wideband
Decoder
6224 (dsPIC33E)
0 (dsPIC33E)
2
X data memory
2
Y data memory
Narrowband Encoder and Narrowband 2810 (dsPIC33F)
714 (dsPIC33F)
Decoder
2
X data memory
2
Y data memory
Narrowband Encoder and Narrowband 6224 (dsPIC33E)
0 (dsPIC33E)
Decoder
2
X data memory
2
Y data memory
TABLE 4-12:
MIPS
Function
MIPS
Typical Call Frequency
Speex8KHzEncoderInit()
0.01
Once
Speex8KHzDecoderInit()
0.02
Once
Speex8KHzEncode()
17.1 (dsPIC33F)
22.2 (dsPIC33E)
20 ms
Speex8KHzDecode()
2.1 (dsPIC33F)
2.7 (dsPIC33E)
20 ms
Speex16KHzEncoderInit()
0.02
Once
Speex16KHzDecoderInit()
0.04
Once
Speex16KHzEncode()
21.5 MIPS (dsPIC33F)
27.8 MIPS (dsPIC33E)
20 ms
Speex16KHzDecode()
4.5 (dsPIC33F)
5.6 (dsPIC33E)
20 ms
TABLE 4-13:
DATA FORMAT
I/O Type
DS70328C-page 46
Data Type
Encoder Input
16-bit linear PCM data
Decoder Output
16-bit linear PCM data
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
4.8
API FUNCTIONS
This section lists and describes the API functions that are available in the dsPIC DSC
Speex Speech Encoding/Decoding Library. The functions are listed below followed by
their individual detailed descriptions:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Speex8KHzEncoderInit
Speex8KHzDecoderInit
Speex16KHzEncoderInit
Speex16KHzDecoderInit
Speex8KHzEncode
Speex8KHzDecode
Speex16KHzEncode
Speex16KHzDecode
SPEEX_NORMAL_PITCH
SPEEX_LOW_PITCH
NB_SPEEX_BITRATE_8K
NB_SPEEX_BITRATE_11K
WB_SPEEX_BITRATE_9K8
WB_SPEEX_BITRATE_12K8
NB_SPEEX_ENCODER_INPUT_SIZE
NB_SPEEX_DECODER_OUTPUT_SIZE
WB_SPEEX_ENCODER_INPUT_SIZE
WB_SPEEX_DECODER_OUTPUT_SIZE
NB_SPEEX_ENCODED_FRAME_SIZE_8K
NB_SPEEX_ENCODED_FRAME_SIZE_11K
WB_SPEEX_ENCODED_FRAME_SIZE_9K8
WB_SPEEX_ENCODED_FRAME_SIZE_9K8
WB_SPEEX_ENCODED_FRAME_SIZE_12K8
SPEEX_ENCODER_X_SCRATCH_SIZE
SPEEX_ENCODER_Y_SCRATCH_SIZE
SPEEX_DECODER_X_SCRATCH_SIZE
SPEEX_DECODER_Y_SCRATCH_SIZE
NB_SPEEX_ENCODER_STATE_SIZE
NB_SPEEX_DECODER_STATE_SIZE
WB_SPEEX_ENCODER_STATE_SIZE
WB_SPEEX_DECODER_STATE_SIZE
SPEEX_INVALID_MODE_ID
© 2008-2011 Microchip Technology Inc.
DS70328C-page 47
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
Speex8KHzEncoderInit
Description
Initializes the Narrowband Speex Encoder.
Include
speex.h
speex_8k.h
Prototype
void Speex8KHzEncoderInit(int* encoderState, unsigned char*
xScratchMem, unsigned char* yScratchMem,int bitRate,int pitch);
Arguments
encoderState a pointer to the state memory for this instance of Narrowband Speex
xScratchMem
yScratchMem
bitRate
pitch
encoder
a pointer to an area of scratch memory in X RAM used by the
encoder
a pointer to an area of scratch memory in Y RAM used by the
encoder
a value representing the bit rate at which the encoder will operate.
Value can be either NB_SPEEX_BITRATE_8K for 8 kbps mode or
NB_SPEEX_BITRATE_11K for 11 kbps mode.
a value representing the pitch range for the encoder. Value can be
either SPEEX_LOW_PITCH for low pitch range or
SPEEX_NORMAL_PITCH for normal pitch range.
Return Value
None.
Remarks
Each audio channel must have its own encoder state. Encoders can share scratch
memory as long as the encode functions are called in the same context (that is, an
encode function is not called in an ISR or another task).
Code Example
int
encoder
[NB_SPEEX_ENCODER_STATE_SIZE] _XBSS(2);
unsigned char
xScratchMem [SPEEX_ENCODER_X_SCRATCH_SIZE] _XBSS(2);
unsigned char
yScratchMem [SPEEX_ENCODER_Y_SCRATCH_SIZE] _YBSS(2);
.
.
.
/* Initialize an Narrowband Speex encoder at bit
* rate of 8 kbps and normal pitch range */
Speex8KHzEncoderInit(encoder,xScratchMem,yScratchMem,NB_SPEEX_BITRATE_
8K, SPEEX_NORMAL_PITCH);
DS70328C-page 48
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
Speex8KHzDecoderInit
Description
Initializes the Narrowband Speex Decoder.
Include
speex.h
speex_8k.h
Prototype
void Speex8KHzDecoderInit(int* decoderState, unsigned char*
xScratchMem, unsigned char* yScratchMem);
Arguments
decoderState a pointer to the state memory for this instance of Narrowband Speex
xScratchMem
yScratchMem
decoder
a pointer to an area of scratch memory in X RAM used by the
decoder
a pointer to an area of scratch memory in Y RAM used by the
decoder
Return Value
None.
Remarks
Each audio channel must have its own decoder state. Decoders can share scratch
memory as long as the decode functions are called in the same context (that is, a
decode function is not called in an ISR or another task).
Code Example
int
decoder
[NB_SPEEX_DECODER_STATE_SIZE] _XBSS(2);
unsigned char
xScratchMem [SPEEX_DECODER_X_SCRATCH_SIZE] _XBSS(2);
unsigned char
yScratchMem [SPEEX_DECODER_Y_SCRATCH_SIZE] _YBSS(2);
.
.
.
/* Initialize a Narrowband Speex decoder */
Speex8KHzDecoderInit(decoder,xScratchMem,yScratchMem);
© 2008-2011 Microchip Technology Inc.
DS70328C-page 49
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
Speex16KHzEncoderInit
Description
Initializes the Wideband Speex Encoder.
Include
speex.h
Prototype
void Speex16KHzEncoderInit(int* encoderState, unsigned char*
xScratchMem, unsigned char* yScratchMem,int bitRate,int pitch);
Arguments
encoderState a pointer to the state memory for this instance of Narrowband Speex
xScratchMem
yScratchMem
bitRate
pitch
encoder
a pointer to an area of scratch memory in X RAM used by the
encoder
a pointer to an area of scratch memory in Y RAM used by the
encoder
a value representing the bit rate at which the encoder will operate.
Value can be either WB_SPEEX_BITRATE_9K8 for 9.8 kbps mode or
WB_SPEEX_BITRATE_12K8 for 12.8 kbps mode
a value representing the pitch range for the encoder. Value can be
either SPEEX_LOW_PITCH for low pitch range or SPEEX_NORMAL_PITCH
for normal pitch range
Return Value
None.
Remarks
Each audio channel must have its own encoder state. Encoders can share scratch
memory as long as the encode functions are called in the same context (that is, an
encode function is not called in an ISR or another task).
Code Example
int
unsigned char
unsigned char
encoder
xScratchMem
yScratchMem
[WB_SPEEX_ENCODER_STATE_SIZE] _XBSS(2);
[SPEEX_ENCODER_X_SCRATCH_SIZE] _XBSS(2);
[SPEEX_ENCODER_Y_SCRATCH_SIZE] _YBSS(2);
/* Initialize a Wideband Speex encoder at bit
* rate of 12.8 kbps and normal pitch range */
.
.
.
Speex16KHzEncoderInit(encoder,xScratchMem,yScratchMem,WB_SPEEX_BITRATE
_12K8, SPEEX_NORMAL_PITCH);
DS70328C-page 50
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
Speex16KHzDecoderInit
Description
Initializes the Wideband Speex Decoder.
Include
speex.h
Prototype
void Speex16KHzDecoderInit(int* decoderState, unsigned char*
xScratchMem, unsigned char* yScratchMem);
Arguments
decoderState a pointer to the state memory for this instance of Wideband Speex
xScratchMem
yScratchMem
decoder
a pointer to an area of scratch memory in X RAM used by the
decoder
a pointer to an area of scratch memory in Y RAM used by the
decoder
Return Value
None.
Remarks
Each audio channel must have its own decoder state. Decoders can share scratch
memory as long as the decode functions are called in the same context (that is, a
decode function is not called in an ISR or another task).
Code Example
int
decoder
[WB_SPEEX_DECODER_STATE_SIZE] _XBSS(2);
unsigned char
xScratchMem [SPEEX_DECODER_X_SCRATCH_SIZE] _XBSS(2);
unsigned char
yScratchMem [SPEEX_DECODER_Y_SCRATCH_SIZE] _YBSS(2);
.
.
.
/* Initialize a Wideband Speex decoder */
Speex16KHzDecoderInit(decoder,xScratchMem,yScratchMem);
© 2008-2011 Microchip Technology Inc.
DS70328C-page 51
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
Speex8KHzEncode
Description
Invokes the Narrowband Speex Encoder to encode a frame of data.
Include
speex.h
speex_8k.h
Prototype
int Speex8KHzEncode(int* encoderState, int * input, char* output);
Arguments
encoderState a pointer to the state memory for this instance of Narrowband Speex
input
output
encoder
a pointer to frame of raw speech data
a pointer to the encoded frame
Return Value
Returns the size of the encoded frame in bytes.
Remarks
Size of output array depends on the encoder mode. It can be either
NB_SPEEX_ENCODER_OUTPUT_SIZE_8K or NB_SPEEX_ENCODER_OUTPUT_SIZE_11K. Size
of the input array must be NB_SPEEX_ENCODER_INPUT_SIZE.
Code Example
int
encoder
[NB_SPEEX_ENCODER_STATE_SIZE] _XBSS(2);
unsigned char
xScratchMem [SPEEX_ENCODER_X_SCRATCH_SIZE] _XBSS(2);
unsigned char
yScratchMem [SPEEX_ENCODER_Y_SCRATCH_SIZE] _YBSS(2);
int
inputFrame [NB_SPEEX_ENCODER_INPUT_SIZE] _XBSS(2);
char
outputFrame [NB_SPEEX_ENCODER_OUTPUT_SIZE_8K] _XBSS(2);
int
bytes;
.
.
.
/* Initialize a Narrowband Speex encoder for operation
* at 8 kbps and normal pitch range */
Speex8KHzEncoderInit(encoder,xScratchMem,yScratchMem,NB_SPEEX_BITRATE_
8K,SPEEX_NORMAL_PITCH);
.
.
.
/* Encode a frame of data */
bytes = Speex8KHzEncode(encoder,inputFrame,outputFrame);
DS70328C-page 52
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
Speex8KHzDecode
Description
Invokes the Narrowband Speex Decoder to decode an encoded frame of data.
Include
speex.h
speex_8k.h
Prototype
int Speex8KHzDecode(int* decoderState, char * input, int* output);
Arguments
decoderState a pointer to the state memory for this instance of Narrowband Speex
input
output
decoder
a pointer to frame of encoded data
a pointer to the decoded data
Return Value
Returns ‘0’ if no error was encountered. Returns SPEEX_INVALID_MODE_ID if the
input encoded Speex frame has an unsupported mode.
Remarks
The decoder uses the information stored in the packet to obtain encoded frame pitch
range and the encoded mode. The NB_SPEEX_DECODER_OUTPUT_SIZE macro can be
used to specify the output array size.
Code Example
int
unsigned char
unsigned char
char
int
int
.
.
.
/* Initialize
decoder
xScratchMem
yScratchMem
inputFrame
outputFrame
retVal;
[NB_SPEEX_DECODER_STATE_SIZE] _XBSS(2);
[SPEEX_DECODER_X_SCRATCH_SIZE] _XBSS(2);
[SPEEX_DECODER_Y_SCRATCH_SIZE] _YBSS(2);
[NB_SPEEX_ENCODER_OUTPUT_SIZE_8K] _XBSS(2);
[NB_SPEEX_DECODER_OUTPUT_SIZE] _XBSS(2);
a Narrowband Speex decoder */
Speex8KHzDecoderInit(decoder,xScratchMem,yScratchMem);
.
.
.
/* Decode a frame of data */
retVal = Speex8KHzDecode(encoder,inputFrame,outputFrame);
© 2008-2011 Microchip Technology Inc.
DS70328C-page 53
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
Speex16KHzEncode
Description
Invokes the Wideband Speex Encoder to encode a frame of data.
Include
speex.h
Prototype
int Speex16KHzEncode(int* encoderState, int * input, char* output);
Arguments
encoderState a pointer to the state memory for this instance of Wideband Speex
input
output
encoder
a pointer to frame of raw speech data
a pointer to the encoded frame
Return Value
Returns the size of the encoded frame in bytes.
Remarks
Size of output array depends on the encoder mode. It can be either
WB_SPEEX_ENCODER_OUTPUT_SIZE_9K8 or WB_SPEEX_ENCODER_OUTPUT_SIZE_12K8.
Size of input array must be WB_SPEEX_ENCODER_INPUT_SIZE.
Code Example
int
encoder
[WB_SPEEX_ENCODER_STATE_SIZE] _XBSS(2);
unsigned char xScratchMem [SPEEX_ENCODER_X_SCRATCH_SIZE] _XBSS(2);
unsigned char yScratchMem [SPEEX_ENCODER_Y_SCRATCH_SIZE] _YBSS(2);
int
inputFrame [WB_SPEEX_ENCODER_INPUT_SIZE] _XBSS(2);
char
outputFrame [WB_SPEEX_ENCODER_OUTPUT_SIZE_9K8] _XBSS(2);
int
bytes;
.
.
.
/* Initialize a Wideband Speex encoder for operation
* at 9.8 kbps and normal pitch range */
Speex16KHzEncoderInit(encoder,xScratchMem,yScratchMem,NB_SPEEX_BITRATE
_9K8,SPEEX_NORMAL_PITCH);
.
.
.
/* Encode a frame of data */
bytes = Speex16KHzEncode(encoder,inputFrame,outputFrame);
DS70328C-page 54
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
Speex16KHzDecode
Description
Invokes the Wideband Speex Decoder to decode an encoded frame of data.
Include
speex.h
Prototype
int Speex16KHzDecode(int* decoderState, char * input, int* output);
Arguments
decoderState a pointer to the state memory for this instance of Wideband Speex
input
output
decoder
a pointer to frame of encoded data
a pointer to the decoded data
Return Value
Returns ‘0’ if no error was encountered. Returns SPEEX_INVALID_MODE_ID if the
packet has an invalid mode.
Remarks
The decoder uses the information stored in the packet to obtain encoded frame pitch
range and the encoded mode. The WB_SPEEX_DECODER_OUTPUT_SIZE macro can be
used to specify the output array size.
Code Example
int
unsigned char
unsigned char
char
int
int
.
.
.
/* Initialize
decoder
xScratchMem
yScratchMem
inputFrame
outputFrame
retVal;
[WB_SPEEX_DECODER_STATE_SIZE] _XBSS(2);
[SPEEX_DECODER_X_SCRATCH_SIZE] _XBSS(2);
[SPEEX_DECODER_Y_SCRATCH_SIZE] _YBSS(2);
[WB_SPEEX_ENCODER_OUTPUT_SIZE_9K8] _XBSS(2);
[WB_SPEEX_DECODER_OUTPUT_SIZE] _XBSS(2);
a Wideband Speex decoder */
Speex16KHzDecoderInit(decoder,xScratchMem,yScratchMem);
.
.
.
/* Decode a frame of data */
retVal = Speex16KHzDecode(decoder,inputFrame,outputFrame);
© 2008-2011 Microchip Technology Inc.
DS70328C-page 55
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
SPEEX_NORMAL_PITCH
Description
Indicates to the Speex encoder to use normal pitch range.
Value
0
SPEEX_LOW_PITCH
Description
Indicates to the Speex encoder to use low pitch range.
Value
1
NB_SPEEX_BITRATE_8K
Description
Indicates to the Narrowband Speex encoder to use the 8 kbps mode.
Value
3
NB_SPEEX_BITRATE_11K
Description
Indicates to the Narrowband Speex encoder to use the 11 kbps mode.
Value
4
WB_SPEEX_BITRATE_9K8
Description
Indicates to the Wideband Speex encoder to use the 9.8 kbps mode.
Value
3
DS70328C-page 56
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
WB_SPEEX_BITRATE_12K8
Description
Indicates to the Wideband Speex encoder to use the 12.8 kbps mode.
Value
4
NB_SPEEX_ENCODER_INPUT_SIZE
Description
Defines the size of the Narrowband Speex encoder input integer type array.
Value
160
NB_SPEEX_DECODER_OUTPUT_SIZE
Description
Defines the size of the Narrowband Speex decoder output integer type array.
Value
160
WB_SPEEX_ENCODER_INPUT_SIZE
Description
Defines the size of the Wideband Speex encoder input integer type array.
Value
320
WB_SPEEX_DECODER_OUTPUT_SIZE
Description
Defines the size of the Wideband Speex decoder output integer type array.
Value
320
© 2008-2011 Microchip Technology Inc.
DS70328C-page 57
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
NB_SPEEX_ENCODED_FRAME_SIZE_8K
Description
Defines the size of the Narrowband Speex encoder output char type array for 8 kbps
mode.
Value
20
NB_SPEEX_ENCODED_FRAME_SIZE_11K
Description
Defines the size of the Narrowband Speex encoder output char type array for 11 kbps
mode.
Value
28
WB_SPEEX_ENCODED_FRAME_SIZE_9K8
Description
Defines the size of the Wideband Speex encoder output char type array for 9.8 kbps
mode.
Value
25
WB_SPEEX_ENCODED_FRAME_SIZE_12K8
Description
Defines the size of the Wideband Speex encoder output char type array for 12.8 kbps
mode.
Value
32
DS70328C-page 58
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
SPEEX_ENCODER_X_SCRATCH_SIZE
Description
Defines the Speex Encoder X scratch memory (unsigned char type array) size.
Value
800
SPEEX_ENCODER_Y_SCRATCH_SIZE
Description
Defines the Speex Encoder Y scratch memory (unsigned char type array) size.
Value
2700 when using libspeex.a
1500 when using libspeex_8k.a
SPEEX_DECODER_X_SCRATCH_SIZE
Description
Defines the Speex Decoder X scratch memory (unsigned char type array) size.
Value
82
SPEEX_DECODER_Y_SCRATCH_SIZE
Description
Defines the Speex Decoder Y scratch memory (unsigned char type array) size.
Value
850
NB_SPEEX_ENCODER_STATE_SIZE
Description
Defines the Narrowband Speex Encoder State (integer array) size.
Value
0x335
© 2008-2011 Microchip Technology Inc.
DS70328C-page 59
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
NB_SPEEX_DECODER_STATE_SIZE
Description
Defines the Narrowband Speex Decoder State (integer array) size.
Value
0x2B9
WB_SPEEX_ENCODER_STATE_SIZE
Description
Defines the Wideband Speex Encoder State (integer array) size.
Value
0x43C
WB_SPEEX_DECODER_STATE_SIZE
Description
Defines the Wideband Speex Encoder State (integer array) size.
Value
0x39A
SPEEX_INVALID_MODE_ID
Description
The value returned by the decoder if the mode ID of the encoded frame is incorrect.
Value
0xFFFE
DS70328C-page 60
© 2008-2011 Microchip Technology Inc.
Application Programming Interface
4.9
APPLICATION TIPS
The following are a few tips to consider when using the dsPIC DSC Speex Speech
Encoding/Decoding Library.
1. The optimum input signal levels for testing audio systems are generally
considered to be between -10 dBm0 and -30 dBm0. If digital input speech levels
have peaks that are up to three-fourths of full range, good use is being made of
the available precision; levels higher than this carry a risk of amplitude clipping.
2. It is possible for the Encoder and Decoder to share scratch memories. For this
to occur, the Encoder and Decoder functions should be invoked in the same
process thread or task. That is, the Encoder or Decoder sharing scratch
memories should not be invoked in an ISR. To use the same scratch memories,
allocate the Encoder X and Y scratch memories and set up the Decoder to use
these.
3. While using multiple encoders or decoders, it is possible for the encoders and
decoders to share the same scratch memory. The precautions mentioned in tip 2
should be followed.
4. For devices with 8 KB RAM (such as the dsPIC30F DSC devices), use the
Narrowband-Only library archive. This implementation of a single Narrowband
mode has been optimized for the 8 KB devices.
© 2008-2011 Microchip Technology Inc.
DS70328C-page 61
dsPIC® DSC Speex Speech Encoding/Decoding Library User’s Guide
NOTES:
DS70328C-page 62
© 2008-2011 Microchip Technology Inc.
dsPIC® DSC SPEEX SPEECH
ENCODING/DECODING
LIBRARY USER’S GUIDE
Index
A
M
API ................................................................ 5
Microchip Internet Web Site ................................ 8
Modes
Narrowband ............................................ 16
Wideband ............................................... 16
C
Code Excited Linear Prediction (CELP) ............... 12
Communication Setup Files .............................. 15
Customer Notification Service ............................. 8
Customer Support ............................................ 8
D
Demonstration Files ........................................ 20
Communication ........................................ 16
Documentation ........................................ 20
Library Archive ........................................ 20
PCEU .................................................... 20
RecordPlay ............................................. 19
Documentation
Conventions .............................................. 6
Layout ..................................................... 5
I
Installation
Installing the Library .................................. 15
Internet Address .............................................. 8
O
Optional Hardware
Audio PICtail™ Plus Daughter Board ........... 21
Explorer 16 Development Board .................. 21
P
PC Encoder Utility (PCEU) ............................... 13
R
Reading, Recommended ................................... 7
Readme ......................................................... 7
S
Speech Signal Compression ............................. 11
System Requirements ..................................... 14
W
Warranty Registration ....................................... 6
WWW Address ................................................ 8
L
Layout ........................................................... 5
Library Archive .............................................. 20
© 2008-2011 Microchip Technology Inc.
DS70328C-page 63
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