+++ /dev/null
-The files in this directory comprise ANSI-C language reference implementations
-of the CCITT (International Telegraph and Telephone Consultative Committee)
-G.711, G.721 and G.723 voice compressions. They have been tested on Sun
-SPARCstations and passed 82 out of 84 test vectors published by CCITT
-(Dec. 20, 1988) for G.721 and G.723. [The two remaining test vectors,
-which the G.721 decoder implementation for u-law samples did not pass,
-may be in error because they are identical to two other vectors for G.723_40.]
-
-This source code is released by Sun Microsystems, Inc. to the public domain.
-Please give your acknowledgement in product literature if this code is used
-in your product implementation.
-
-Sun Microsystems supports some CCITT audio formats in Solaris 2.0 system
-software. However, Sun's implementations have been optimized for higher
-performance on SPARCstations.
-
-
-The source files for CCITT conversion routines in this directory are:
-
- g72x.h header file for g721.c, g723_24.c and g723_40.c
- g711.c CCITT G.711 u-law and A-law compression
- g72x.c common denominator of G.721 and G.723 ADPCM codes
- g721.c CCITT G.721 32Kbps ADPCM coder (with g72x.c)
- g723_24.c CCITT G.723 24Kbps ADPCM coder (with g72x.c)
- g723_40.c CCITT G.723 40Kbps ADPCM coder (with g72x.c)
-
-
-Simple conversions between u-law, A-law, and 16-bit linear PCM are invoked
-as follows:
-
- unsigned char ucode, acode;
- short pcm_val;
-
- ucode = linear2ulaw(pcm_val);
- ucode = alaw2ulaw(acode);
-
- acode = linear2alaw(pcm_val);
- acode = ulaw2alaw(ucode);
-
- pcm_val = ulaw2linear(ucode);
- pcm_val = alaw2linear(acode);
-
-
-The other CCITT compression routines are invoked as follows:
-
- #include "g72x.h"
-
- struct g72x_state state;
- int sample, code;
-
- g72x_init_state(&state);
- code = {g721,g723_24,g723_40}_encoder(sample, coding, &state);
- sample = {g721,g723_24,g723_40}_decoder(code, coding, &state);
-
-where
- coding = AUDIO_ENCODING_ULAW for 8-bit u-law samples
- AUDIO_ENCODING_ALAW for 8-bit A-law samples
- AUDIO_ENCODING_LINEAR for 16-bit linear PCM samples
-
-
-
-This directory also includes the following sample programs:
-
- encode.c CCITT ADPCM encoder
- decode.c CCITT ADPCM decoder
- Makefile makefile for the sample programs
-
-
-The sample programs contain examples of how to call the various compression
-routines and pack/unpack the bits. The sample programs read byte streams from
-stdin and write to stdout. The input/output data is raw data (no file header
-or other identifying information is embedded). The sample programs are
-invoked as follows:
-
- encode [-3|4|5] [-a|u|l] <infile >outfile
- decode [-3|4|5] [-a|u|l] <infile >outfile
-where:
- -3 encode to (decode from) G.723 24kbps (3-bit) data
- -4 encode to (decode from) G.721 32kbps (4-bit) data [the default]
- -5 encode to (decode from) G.723 40kbps (5-bit) data
- -a encode from (decode to) A-law data
- -u encode from (decode to) u-law data [the default]
- -l encode from (decode to) 16-bit linear data
-
-Examples:
- # Read 16-bit linear and output G.721
- encode -4 -l <pcmfile >g721file
-
- # Read 40Kbps G.723 and output A-law
- decode -5 -a <g723file >alawfile
-
- # Compress and then decompress u-law data using 24Kbps G.723
- encode -3 <ulawin | deoced -3 >ulawout
-
projects / Faustine.git / blobdiff