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FFmpeg/libavcodec/g726.c
Stefano Sabatini 72415b2adb Define AVMediaType enum, and use it instead of enum CodecType, which 
is deprecated and will be dropped at the next major bump.

Originally committed as revision 22735 to svn://svn.ffmpeg.org/ffmpeg/trunk
2010-03-30 23:30:55 +00:00

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/*
* G.726 ADPCM audio codec
* Copyright (c) 2004 Roman Shaposhnik
*
* This is a very straightforward rendition of the G.726
* Section 4 "Computational Details".
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <limits.h>
#include "avcodec.h"
#include "get_bits.h"
#include "put_bits.h"
/**
* G.726 11bit float.
* G.726 Standard uses rather odd 11bit floating point arithmentic for
* numerous occasions. It's a mistery to me why they did it this way
* instead of simply using 32bit integer arithmetic.
*/
typedef struct Float11 {
uint8_t sign; /**< 1bit sign */
uint8_t exp; /**< 4bit exponent */
uint8_t mant; /**< 6bit mantissa */
} Float11;
static inline Float11* i2f(int i, Float11* f)
{
f->sign = (i < 0);
if (f->sign)
i = -i;
f->exp = av_log2_16bit(i) + !!i;
f->mant = i? (i<<6) >> f->exp : 1<<5;
return f;
}
static inline int16_t mult(Float11* f1, Float11* f2)
{
int res, exp;
exp = f1->exp + f2->exp;
res = (((f1->mant * f2->mant) + 0x30) >> 4);
res = exp > 19 ? res << (exp - 19) : res >> (19 - exp);
return (f1->sign ^ f2->sign) ? -res : res;
}
static inline int sgn(int value)
{
return (value < 0) ? -1 : 1;
}
typedef struct G726Tables {
const int* quant; /**< quantization table */
const int16_t* iquant; /**< inverse quantization table */
const int16_t* W; /**< special table #1 ;-) */
const uint8_t* F; /**< special table #2 */
} G726Tables;
typedef struct G726Context {
G726Tables tbls; /**< static tables needed for computation */
Float11 sr[2]; /**< prev. reconstructed samples */
Float11 dq[6]; /**< prev. difference */
int a[2]; /**< second order predictor coeffs */
int b[6]; /**< sixth order predictor coeffs */
int pk[2]; /**< signs of prev. 2 sez + dq */
int ap; /**< scale factor control */
int yu; /**< fast scale factor */
int yl; /**< slow scale factor */
int dms; /**< short average magnitude of F[i] */
int dml; /**< long average magnitude of F[i] */
int td; /**< tone detect */
int se; /**< estimated signal for the next iteration */
int sez; /**< estimated second order prediction */
int y; /**< quantizer scaling factor for the next iteration */
int code_size;
} G726Context;
static const int quant_tbl16[] = /**< 16kbit/s 2bits per sample */
{ 260, INT_MAX };
static const int16_t iquant_tbl16[] =
{ 116, 365, 365, 116 };
static const int16_t W_tbl16[] =
{ -22, 439, 439, -22 };
static const uint8_t F_tbl16[] =
{ 0, 7, 7, 0 };
static const int quant_tbl24[] = /**< 24kbit/s 3bits per sample */
{ 7, 217, 330, INT_MAX };
static const int16_t iquant_tbl24[] =
{ INT16_MIN, 135, 273, 373, 373, 273, 135, INT16_MIN };
static const int16_t W_tbl24[] =
{ -4, 30, 137, 582, 582, 137, 30, -4 };
static const uint8_t F_tbl24[] =
{ 0, 1, 2, 7, 7, 2, 1, 0 };
static const int quant_tbl32[] = /**< 32kbit/s 4bits per sample */
{ -125, 79, 177, 245, 299, 348, 399, INT_MAX };
static const int16_t iquant_tbl32[] =
{ INT16_MIN, 4, 135, 213, 273, 323, 373, 425,
425, 373, 323, 273, 213, 135, 4, INT16_MIN };
static const int16_t W_tbl32[] =
{ -12, 18, 41, 64, 112, 198, 355, 1122,
1122, 355, 198, 112, 64, 41, 18, -12};
static const uint8_t F_tbl32[] =
{ 0, 0, 0, 1, 1, 1, 3, 7, 7, 3, 1, 1, 1, 0, 0, 0 };
static const int quant_tbl40[] = /**< 40kbit/s 5bits per sample */
{ -122, -16, 67, 138, 197, 249, 297, 338,
377, 412, 444, 474, 501, 527, 552, INT_MAX };
static const int16_t iquant_tbl40[] =
{ INT16_MIN, -66, 28, 104, 169, 224, 274, 318,
358, 395, 429, 459, 488, 514, 539, 566,
566, 539, 514, 488, 459, 429, 395, 358,
318, 274, 224, 169, 104, 28, -66, INT16_MIN };
static const int16_t W_tbl40[] =
{ 14, 14, 24, 39, 40, 41, 58, 100,
141, 179, 219, 280, 358, 440, 529, 696,
696, 529, 440, 358, 280, 219, 179, 141,
100, 58, 41, 40, 39, 24, 14, 14 };
static const uint8_t F_tbl40[] =
{ 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 6,
6, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
static const G726Tables G726Tables_pool[] =
{{ quant_tbl16, iquant_tbl16, W_tbl16, F_tbl16 },
{ quant_tbl24, iquant_tbl24, W_tbl24, F_tbl24 },
{ quant_tbl32, iquant_tbl32, W_tbl32, F_tbl32 },
{ quant_tbl40, iquant_tbl40, W_tbl40, F_tbl40 }};
/**
* Para 4.2.2 page 18: Adaptive quantizer.
*/
static inline uint8_t quant(G726Context* c, int d)
{
int sign, exp, i, dln;
sign = i = 0;
if (d < 0) {
sign = 1;
d = -d;
}
exp = av_log2_16bit(d);
dln = ((exp<<7) + (((d<<7)>>exp)&0x7f)) - (c->y>>2);
while (c->tbls.quant[i] < INT_MAX && c->tbls.quant[i] < dln)
++i;
if (sign)
i = ~i;
if (c->code_size != 2 && i == 0) /* I'm not sure this is a good idea */
i = 0xff;
return i;
}
/**
* Para 4.2.3 page 22: Inverse adaptive quantizer.
*/
static inline int16_t inverse_quant(G726Context* c, int i)
{
int dql, dex, dqt;
dql = c->tbls.iquant[i] + (c->y >> 2);
dex = (dql>>7) & 0xf; /* 4bit exponent */
dqt = (1<<7) + (dql & 0x7f); /* log2 -> linear */
return (dql < 0) ? 0 : ((dqt<<dex) >> 7);
}
static int16_t g726_decode(G726Context* c, int I)
{
int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0;
Float11 f;
int I_sig= I >> (c->code_size - 1);
dq = inverse_quant(c, I);
/* Transition detect */
ylint = (c->yl >> 15);
ylfrac = (c->yl >> 10) & 0x1f;
thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint;
tr= (c->td == 1 && dq > ((3*thr2)>>2));
if (I_sig) /* get the sign */
dq = -dq;
re_signal = c->se + dq;
/* Update second order predictor coefficient A2 and A1 */
pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0;
dq0 = dq ? sgn(dq) : 0;
if (tr) {
c->a[0] = 0;
c->a[1] = 0;
for (i=0; i<6; i++)
c->b[i] = 0;
} else {
/* This is a bit crazy, but it really is +255 not +256 */
fa1 = av_clip((-c->a[0]*c->pk[0]*pk0)>>5, -256, 255);
c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7);
c->a[1] = av_clip(c->a[1], -12288, 12288);
c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8);
c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]);
for (i=0; i<6; i++)
c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8);
}
/* Update Dq and Sr and Pk */
c->pk[1] = c->pk[0];
c->pk[0] = pk0 ? pk0 : 1;
c->sr[1] = c->sr[0];
i2f(re_signal, &c->sr[0]);
for (i=5; i>0; i--)
c->dq[i] = c->dq[i-1];
i2f(dq, &c->dq[0]);
c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */
c->td = c->a[1] < -11776;
/* Update Ap */
c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5);
c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7);
if (tr)
c->ap = 256;
else {
c->ap += (-c->ap) >> 4;
if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3))
c->ap += 0x20;
}
/* Update Yu and Yl */
c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120);
c->yl += c->yu + ((-c->yl)>>6);
/* Next iteration for Y */
al = (c->ap >= 256) ? 1<<6 : c->ap >> 2;
c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6;
/* Next iteration for SE and SEZ */
c->se = 0;
for (i=0; i<6; i++)
c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]);
c->sez = c->se >> 1;
for (i=0; i<2; i++)
c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]);
c->se >>= 1;
return av_clip(re_signal << 2, -0xffff, 0xffff);
}
static av_cold int g726_reset(G726Context* c, int index)
{
int i;
c->tbls = G726Tables_pool[index];
for (i=0; i<2; i++) {
c->sr[i].mant = 1<<5;
c->pk[i] = 1;
}
for (i=0; i<6; i++) {
c->dq[i].mant = 1<<5;
}
c->yu = 544;
c->yl = 34816;
c->y = 544;
return 0;
}
#if CONFIG_ADPCM_G726_ENCODER
static int16_t g726_encode(G726Context* c, int16_t sig)
{
uint8_t i;
i = quant(c, sig/4 - c->se) & ((1<<c->code_size) - 1);
g726_decode(c, i);
return i;
}
#endif
/* Interfacing to the libavcodec */
static av_cold int g726_init(AVCodecContext * avctx)
{
G726Context* c = avctx->priv_data;
unsigned int index;
if (avctx->sample_rate <= 0) {
av_log(avctx, AV_LOG_ERROR, "Samplerate is invalid\n");
return -1;
}
index = (avctx->bit_rate + avctx->sample_rate/2) / avctx->sample_rate - 2;
if (avctx->bit_rate % avctx->sample_rate && avctx->codec->encode) {
av_log(avctx, AV_LOG_ERROR, "Bitrate - Samplerate combination is invalid\n");
return -1;
}
if(avctx->channels != 1){
av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n");
return -1;
}
if(index>3){
av_log(avctx, AV_LOG_ERROR, "Unsupported number of bits %d\n", index+2);
return -1;
}
g726_reset(c, index);
c->code_size = index+2;
avctx->coded_frame = avcodec_alloc_frame();
if (!avctx->coded_frame)
return AVERROR(ENOMEM);
avctx->coded_frame->key_frame = 1;
if (avctx->codec->decode)
avctx->sample_fmt = SAMPLE_FMT_S16;
return 0;
}
static av_cold int g726_close(AVCodecContext *avctx)
{
av_freep(&avctx->coded_frame);
return 0;
}
#if CONFIG_ADPCM_G726_ENCODER
static int g726_encode_frame(AVCodecContext *avctx,
uint8_t *dst, int buf_size, void *data)
{
G726Context *c = avctx->priv_data;
short *samples = data;
PutBitContext pb;
init_put_bits(&pb, dst, 1024*1024);
for (; buf_size; buf_size--)
put_bits(&pb, c->code_size, g726_encode(c, *samples++));
flush_put_bits(&pb);
return put_bits_count(&pb)>>3;
}
#endif
static int g726_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
G726Context *c = avctx->priv_data;
short *samples = data;
GetBitContext gb;
init_get_bits(&gb, buf, buf_size * 8);
while (get_bits_count(&gb) + c->code_size <= buf_size*8)
*samples++ = g726_decode(c, get_bits(&gb, c->code_size));
if(buf_size*8 != get_bits_count(&gb))
av_log(avctx, AV_LOG_ERROR, "Frame invalidly split, missing parser?\n");
*data_size = (uint8_t*)samples - (uint8_t*)data;
return buf_size;
}
#if CONFIG_ADPCM_G726_ENCODER
AVCodec adpcm_g726_encoder = {
"g726",
AVMEDIA_TYPE_AUDIO,
CODEC_ID_ADPCM_G726,
sizeof(G726Context),
g726_init,
g726_encode_frame,
g726_close,
NULL,
.sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
.long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"),
};
#endif
AVCodec adpcm_g726_decoder = {
"g726",
AVMEDIA_TYPE_AUDIO,
CODEC_ID_ADPCM_G726,
sizeof(G726Context),
g726_init,
NULL,
g726_close,
g726_decode_frame,
.long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"),
};
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