INTRODUCTION
EasyG723.1 is an implementation of
ITU G.723.1. EasyG723.1
support multiple channels concurrent. There is no limit in concurrent channels
and it can up to thousands channels.
EasyG723.1 is a 6.3kbps/5.3kbps coder that encodes/decodes
speech signal. The coder operates on speech frames of 30 ms,
corresponding to 240 samples at a sampling rate of 8000
samples/sec. In addition
to the 30 ms speech frame duration, there is also a look-ahead delay of
7.5 ms, resulting in a total initial algorithmic delay of 37.5ms.
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EasyG723.1 codec specifications
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6.3kbps
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5.3kbps
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Bit rate (kbps)
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6.3
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5.3
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Speech
sampling rate(Hz)
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8000
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8000
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Frame
duration (ms)
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30
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30
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Look-ahead
delay (ms)
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7.5
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7.5
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Samples in one Frame
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240
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240
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Frame size before encode(bytes)
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480
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480
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Frame size after encode(bytes)
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24
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20
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EasyG723.1 has a binary release
version on Windows and Linux. The source code of EasyG723.1 is written by
C/C++, so you can easily port it to UNIX, PPC,DSP, Vxworks or other
operation system that support C/C++.
PACKAGE CONTENTS
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EasyG7231.pdf
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This document
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EasyG7231.lib
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Win32
statically linkable library of G723.1 for Pentium and compatible
processors.
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libG7231.a
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Linux
statically linkable library of G723.1 for Pentium and compatible
processors.
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EasyG7231.h
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API prototypes
and constants declarations required by the sample programs.
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test_encode
directory
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Microsoft
VC6.0 sample application and Linux GCC sample application.
Demonstrating encoder API calls to the codec for encoding a speech
file.
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test_decode
directory
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Microsoft
VC6.0 sample application and Linux GCC sample application.
Demonstrating decoder API calls to the codec for decoding a speech
file.
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The encoder
requires raw 16-bit mono PCM speech data sampled at 8000 Hz as input, i.e.,
without any header information. For every speech frame, consisting of
240*16 bit (480 bytes) samples
CODEC
COMPLEXITY
The codec
complexity is represented as percentage of CPU usage, and is as follows
when tested on an Intel 800 MHz Celeron-MMX:
Encoder 8% CPU time
Decoder 3% CPU time
ABOUT THE ENCODER/DECODER
SAMPLE PROGRAMS
The sample programs
under test_encode
directory and test_decode directory are used to simulate the encoder and decoder, and
demonstrate how to initialize and call the encoding and decoding process.
The encoder and decoder are run as follows (where infile and outfile are raw 16 bit PCM
files sampled at 8 kHz):
EasyG7231_encoder
infile bitstream
EasyG7231_decoder
bitstream outfile
To build the speech
encoder (or decoder) sample programs on Windows, you can open
TEST_ENCODE.dsw or TEST_DECODE.dsw with VC6.0 or later version. After
compiler and link, it will create the execute program of test_encode.exe
or test_decode.exe, you can
test it with following command.
test_encode test.pcm test.cod
test_decode test.cod
test.pcm
To build the speech
encoder (or decoder) sample programs on Linux, you only need rum make command. After you
successfully finished make command, you can run make run to test encoder and decoder.
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EasyG7231_init_encoder
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Description
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Initializes the memory needed by the
encoding process. This function must be called prior to opening or
re-opening a channel.
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Syntax
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#include “EasyG7231.h”
CODER_HANDLE
EasyG7231_init_encoder(bool bUseRate63 );
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Arguments
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bUseRate63 If set to true, then
use G.723.1 6.3kbps
If set to false, then use G.723.1 5.3kbps
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Returned value
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Return a handle that represent an encode
channel, this value will used at EasyG7231_encoder and
EasyG7231_release_encoder
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EasyG7231_encoder
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Description
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Encode an 240 words
speech frame into a 24/20 bytes packed bit stream.
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Syntax
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#include “EasyG7231.h”
bool EasyG7231_encoder(CODER_HANDLE
hEncoder, short *speech, unsigned char *bitstream);
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Arguments
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hEncoder
The coder handle returned by EasyG7231_init_encoder
speech
Input speech buffer containing one frame of 16-bit PCM speech
data.
Bitstream Output bit stream
buffer containing packed bit stream.
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Returned value
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Return true if successful, return
false if failed.
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EasyG7231_release_encoder
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Description
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release the memory allocated by the encoding
process. This function must be called before you quit your program. If
not, it will cause the memory leak.
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Syntax
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#include “EasyG7231.h”
bool
EasyG7231_release_encoder(CODER_HANDLE hEncoder);
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Arguments
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hEncoder The
coder handle returned by EasyG7231_init_encoder
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Returned value
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Return true if successful, return
false if failed.
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EasyG7231_init_decoder
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Description
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Initializes the memory needed by the decoding
process. This function must be called prior to opening or re-opening a
channel.
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Syntax
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#include “EasyG7231.h”
CODER_HANDLE
EasyG7231_init_decoder(bool bUseRate63 );
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Arguments
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bUseRate63 If set to true, then
use G.723.1 6.3kbps
If set to false, then use G.723.1 5.3kbps
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Returned value
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Return a handle that represent an
decode channel, this value will used at EasyG7231_decoder and
EasyG7231_release_decoder
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EasyG7231_decoder
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Description
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Decodes a 24/20 bytes packed bit stream into an 240 words speech
frame.
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Syntax
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#include “EasyG7231.h”
bool
EasyG7231_decoder(CODER_HANDLE hDecoder, unsigned char
*bitstream, short *synth_short );
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Arguments
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hDecoder The
decoder handle returned by EasyG7231_init_decoder
bitstream
Input buffer containing packed bit-stream.
synth_short Output buffer
containing one frame of decoded 16 bits PCM.
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Returned value
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Return true if successful, return false
if failed.
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EasyG7231_release_decoder
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Description
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release the memory allocated by the
decoding process. This function must be called before you quit your
program. If not, it will cause the memory leak.
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Syntax
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#include “EasyG7231.h”
bool
EasyG7231_release_decoder(CODER_HANDLE hDecoder);
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Arguments
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hDecoder
The coder handle returned by EasyG7231_init_decoder
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Returned value
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Return true if successful, return
false if failed.
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Here are some
frequently asked questions about the EasyG723.1.
Q — Is the implementation of G.723.1 interoperable with
the other company’s version?
A — The
implementation of EasyG.723.1 is fully conform to ITU G.723.1, It can interoperate
with other G.723.1 implementations.
Q — What type of speech input format is required?
A — Raw 16-bit mono
PCM sampled at 8000Hz. Do not use .WAV files. They contain a header that
will produce distortion at the start of a decoded audio sample because
the encoder interprets the header as speech data.
Q — How can I convert my .WAV files to raw 16 bit mono PCM
sampled at 8000 Hz?
A — Use an audio
editing tool such as SoX - Sound eXchange. See home.sprynet.com/~cbagwell/sox.html
for
more information
Q — Can I get link on platforms other than Pentium or
compatible?
A — The object code
provided in this package is Microsoft Win32 and Linux x86 compatible, it
is compiled for the Pentium family of processors. If you want to use
EasyG723.1 on other platforms, you should buy the source code of
EasyG723.1. Then you can compile and link.
Q — Is the EasyG723.1 codec able to handle multiple
channels?
A — Yes, It can
handle multiple channels. There is no limited.
Q — Is the EasyG723.1 codec free to use?
A — No, The version
you get freely is a version only for test. If you want to use it in
commercial, you must buy it from www.imtelephone.com. This version has the same
function with the formal release version, but It can only run 60 hours
continuously.
Q — How much does the EasyG723.1 codec cost?
A — The object code of Windows or Linux is $2000/year. The source code
is $40000. You can buy it from www.imtelephone.com.
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Click  to
download Win32/Linux trial version and samples
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Click to
download Win32/Linux optimized trial version and samples,it is 10 times fast than unoptimized version.
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Click to
download PPC trial version and samples
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Click to
download the document
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