initial checkin

Check in contents of upstream 1.4.2 tarball, exclude generated files.

1 files changed, 94 insertions, 0 deletions

diff --git a/src/audio/README_G711 b/src/audio/README_G711
new file mode 100644
index 0000000..23b0e7d
--- /dev/null
+++ b/src/audio/README_G711
@@ -0,0 +1,94 @@
+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
+