EasyG728

 

Introduction

Introduction

EasyG728 is an implementation of ITU G.728.  EasyG728 support multiple channels concurrent. There is no limit in concurrent channels and it can up to thousands channels.

EasyG728 is an 16kbps coder that encodes/decodes speech signal. The coder operates on speech frames of 10 ms, corresponding to 80 samples at a sampling rate of 8000

samples/sec. In addition to the 10 ms speech frame duration, there is also a look-ahead delay of 0.625 ms, resulting in a total initial algorithmic delay of 10.625 ms.

 

EasyG728 codec specifications

 

Bit rate (kbps)

16

Speech sampling rate(Hz)

8000

Frame duration (ms)

10

Look-ahead delay (ms)

0.625

Samples in one Frame

80

Frame size before encode(bytes)

160

Frame size after encode(bytes)

20

 

EasyG728 has a binary release version on Windows and Linux. The source code of EasyG728 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

 

EasyG728.pdf

This document

EasyG728.lib

Win32 statically linkable library of G728 for Pentium and compatible processors.

libG728.a

Linux statically linkable library of G728 for Pentium and compatible processors.

EasyG728.h

API prototypes and constants declarations required by the sample programs.

test_encode directory

Microsoft VC6.0 sample application and Linux GCC sample application. Demonstrating encoder API calls to the codec for encoding a speech file.

test_decode directory

Microsoft VC6.0 sample application and Linux GCC sample application. Demonstrating decoder API calls to the codec for decoding a speech file.

 

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 80*16 bit (160 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  less than 1% CPU time

Decoder  less than 1% 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):

    EasyG728_encoder  infile bitstream

    EasyG728_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.

 

EasyG728 API FUNCTIONS

 

EasyG728_init_encoder

Description

Initializes the memory needed by the encoding process. This function must be called prior to opening or re-opening a channel.

 

Syntax

#include EasyG728.h

 

CODER_HANDLE EasyG728_init_encoder( );

 

Arguments

 

none

 

Returned value

Return a handle that represent an encode channel, this value will used at EasyG728_encoder and EasyG728_release_encoder

 

 

 

EasyG728_encoder

Description

Encode an 80 words speech frame into a 20 bytes packed bit stream.

 

Syntax

#include EasyG728.h

 

bool   EasyG728_encoder(CODER_HANDLE hEncoder, short *speech, unsigned char *bitstream);

 

Arguments

 

hEncoder       The coder handle returned by EasyG728_init_encoder

speech            Input speech buffer containing one frame of 16-bit PCM speech data.

Bitstream       Output bit stream buffer containing packed bit stream.

 

Returned value

Return true if successful, return false if failed.

 

 

 

 

EasyG728_release_encoder

Description

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.

 

Syntax

#include EasyG728.h

 

bool   EasyG728_release_encoder(CODER_HANDLE hEncoder);

 

Arguments

 

hEncoder       The coder handle returned by EasyG728_init_encoder

 

Returned value

Return true if successful, return false if failed.

 

 

 

EasyG728_init_decoder

Description

Initializes the memory needed by the decoding process. This function must be called prior to opening or re-opening a channel.

 

Syntax

#include EasyG728.h

 

CODER_HANDLE EasyG728_init_decoder( );

 

Arguments

 

None

Returned value

Return a handle that represent an decode channel, this value will used at EasyG728_decoder and EasyG728_release_decoder

 

 

 

EasyG728_decoder

Description

Decodes a 20 bytes packed bit stream into an 80 words speech frame.

 

Syntax

#include EasyG728.h

 

bool   EasyG728_decoder(CODER_HANDLE hDecoder, unsigned char *bitstream, short *synth_short );

 

Arguments

 

hDecoder       The decoder handle returned by EasyG728_init_decoder

bitstream         Input buffer containing packed bit-stream.

synth_short     Output buffer containing one frame of decoded 16 bits PCM.

 

Returned value

Return true if successful, return false if failed.

 

 

 

 

EasyG728_release_decoder

Description

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.

 

Syntax

#include EasyG728.h

 

bool   EasyG728_release_decoder(CODER_HANDLE hDecoder);

 

Arguments

 

hDecoder       The coder handle returned by EasyG728_init_decoder

 

Returned value

Return true if successful, return false if failed.

 

 

 

FAQS

Here are some frequently asked questions about the EasyG728.

 

Q — Is the implementation of G.728 interoperable with the other company’s version?

A — The implementation of EasyG.728 is fully conform to ITU G.728, It can interoperate with other G.728 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 EasyG728 on other platforms, you should buy the source code of EasyG728. Then you can compile and link.

 

Q — Is the EasyG728 codec able to handle multiple channels?

A — Yes, It can handle multiple channels. There is no limited.

 

Q — Is the EasyG728 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 EasyG728 codec cost?

A — The 32bits/64bits object code of Windows or Linux is $5,000. The source code is $40000. You can buy it from www.imtelephone.com.  



 

Click to download Win32/Linux trial version and samples

 

Click to download PPC trial version and samples

 

Click to download Windows and Linux 64bits trial version and samples

 

Click to download the document

 

Click to buy the Win32 binary library(no time limitation)

 

Click to buy the Linux binary library(no time limitation)

 

Click to buy the source code

 

Click to buy the Windows 64bits binary library(no time limitation)

 

Click to buy the Linux 64bits binary library(no time limitation)

 

Click to buy the 64bits source code

 

  





 

About us 
Imtelephone.com is a professional company focus on audio communication in IP network and PSTN. We research and develop audio solution on various platforms. We provide the Win32/Linux library or source code for audio/video codec.

 

Contact us
E-mailsupport@imtelephone.com

 

Professional Conference component
http://www.lht2000.com

 

 

 

 

>>Back<<

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copyright(c) 2004-2012 www.Imtelephone.com All rights reserved