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/project/jni/sndfile/src/G72x/g723_24.c

https://github.com/aichunyu/FFPlayer
C | 139 lines | 53 code | 23 blank | 63 comment | 0 complexity | aff53443bc354a5584afaf171f7aca78 MD5 | raw file
  1/*
  2 * This source code is a product of Sun Microsystems, Inc. and is provided
  3 * for unrestricted use.  Users may copy or modify this source code without
  4 * charge.
  5 *
  6 * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
  7 * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  8 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  9 *
 10 * Sun source code is provided with no support and without any obligation on
 11 * the part of Sun Microsystems, Inc. to assist in its use, correction,
 12 * modification or enhancement.
 13 *
 14 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 15 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
 16 * OR ANY PART THEREOF.
 17 *
 18 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 19 * or profits or other special, indirect and consequential damages, even if
 20 * Sun has been advised of the possibility of such damages.
 21 *
 22 * Sun Microsystems, Inc.
 23 * 2550 Garcia Avenue
 24 * Mountain View, California  94043
 25 */
 26
 27/*
 28 * g723_24.c
 29 *
 30 * Description:
 31 *
 32 * g723_24_encoder(), g723_24_decoder()
 33 *
 34 * These routines comprise an implementation of the CCITT G.723 24 Kbps
 35 * ADPCM coding algorithm.  Essentially, this implementation is identical to
 36 * the bit level description except for a few deviations which take advantage
 37 * of workstation attributes, such as hardware 2's complement arithmetic.
 38 *
 39 */
 40
 41#include "g72x.h"
 42#include "g72x_priv.h"
 43
 44/*
 45 * Maps G.723_24 code word to reconstructed scale factor normalized log
 46 * magnitude values.
 47 */
 48static short	_dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};
 49
 50/* Maps G.723_24 code word to log of scale factor multiplier. */
 51static short	_witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};
 52
 53/*
 54 * Maps G.723_24 code words to a set of values whose long and short
 55 * term averages are computed and then compared to give an indication
 56 * how stationary (steady state) the signal is.
 57 */
 58static short	_fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};
 59
 60static short qtab_723_24[3] = {8, 218, 331};
 61
 62/*
 63 * g723_24_encoder()
 64 *
 65 * Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
 66 * Returns -1 if invalid input coding value.
 67 */
 68int
 69g723_24_encoder(
 70	int		sl,
 71	G72x_STATE *state_ptr)
 72{
 73	short		sei, sezi, se, sez;	/* ACCUM */
 74	short		d;			/* SUBTA */
 75	short		y;			/* MIX */
 76	short		sr;			/* ADDB */
 77	short		dqsez;			/* ADDC */
 78	short		dq, i;
 79
 80	/* linearize input sample to 14-bit PCM */
 81	sl >>= 2;		/* sl of 14-bit dynamic range */
 82
 83	sezi = predictor_zero(state_ptr);
 84	sez = sezi >> 1;
 85	sei = sezi + predictor_pole(state_ptr);
 86	se = sei >> 1;			/* se = estimated signal */
 87
 88	d = sl - se;			/* d = estimation diff. */
 89
 90	/* quantize prediction difference d */
 91	y = step_size(state_ptr);	/* quantizer step size */
 92	i = quantize(d, y, qtab_723_24, 3);	/* i = ADPCM code */
 93	dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */
 94
 95	sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
 96
 97	dqsez = sr + sez - se;		/* pole prediction diff. */
 98
 99	update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
100
101	return (i);
102}
103
104/*
105 * g723_24_decoder()
106 *
107 * Decodes a 3-bit CCITT G.723_24 ADPCM code and returns
108 * the resulting 16-bit linear PCM, A-law or u-law sample value.
109 * -1 is returned if the output coding is unknown.
110 */
111int
112g723_24_decoder(
113	int		i,
114	G72x_STATE *state_ptr)
115{
116	short		sezi, sei, sez, se;	/* ACCUM */
117	short		y;			/* MIX */
118	short		sr;			/* ADDB */
119	short		dq;
120	short		dqsez;
121
122	i &= 0x07;			/* mask to get proper bits */
123	sezi = predictor_zero(state_ptr);
124	sez = sezi >> 1;
125	sei = sezi + predictor_pole(state_ptr);
126	se = sei >> 1;			/* se = estimated signal */
127
128	y = step_size(state_ptr);	/* adaptive quantizer step size */
129	dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */
130
131	sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
132
133	dqsez = sr - se + sez;			/* pole prediction diff. */
134
135	update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
136
137	return (sr << 2);	/* sr was of 14-bit dynamic range */
138}
139