libavcodec/g726.c

   1 /*
   2  * G.726 ADPCM audio codec
   3  * Copyright (c) 2004 Roman Shaposhnik
   4  *
   5  * This is a very straightforward rendition of the G.726
   6  * Section 4 "Computational Details".
   7  *
   8  * This file is part of FFmpeg.
   9  *
  10  * FFmpeg is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * FFmpeg is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with FFmpeg; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include "config_components.h"
  26
  27 #include <limits.h>
  28
  29 #include "libavutil/channel_layout.h"
  30 #include "libavutil/opt.h"
  31 #include "avcodec.h"
  32 #include "codec_internal.h"
  33 #include "decode.h"
  34 #include "encode.h"
  35 #include "get_bits.h"
  36 #include "put_bits.h"
  37
  38 /**
  39  * G.726 11-bit float.
  40  * G.726 Standard uses rather odd 11-bit floating point arithmetic for
  41  * numerous occasions. It's a mystery to me why they did it this way
  42  * instead of simply using 32-bit integer arithmetic.
  43  */
  44 typedef struct Float11 {
  45     uint8_t sign;   /**< 1 bit sign */
  46     uint8_t exp;    /**< 4 bits exponent */
  47     uint8_t mant;   /**< 6 bits mantissa */
  48 } Float11;
  49
  50 static inline Float11* i2f(int i, Float11* f)
  51 {
  52     f->sign = (i < 0);
  53     if (f->sign)
  54         i = -i;
  55     f->exp = av_log2_16bit(i) + !!i;
  56     f->mant = i? (i<<6) >> f->exp : 1<<5;
  57     return f;
  58 }
  59
  60 static inline int16_t mult(Float11* f1, Float11* f2)
  61 {
  62         int res, exp;
  63
  64         exp = f1->exp + f2->exp;
  65         res = (((f1->mant * f2->mant) + 0x30) >> 4);
  66         res = exp > 19 ? res << (exp - 19) : res >> (19 - exp);
  67         return (f1->sign ^ f2->sign) ? -res : res;
  68 }
  69
  70 static inline int sgn(int value)
  71 {
  72     return (value < 0) ? -1 : 1;
  73 }
  74
  75 typedef struct G726Tables {
  76     const int* quant;         /**< quantization table */
  77     const int16_t* iquant;    /**< inverse quantization table */
  78     const int16_t* W;         /**< special table #1 ;-) */
  79     const uint8_t* F;         /**< special table #2 */
  80 } G726Tables;
  81
  82 typedef struct G726Context {
  83     AVClass *class;
  84     G726Tables tbls;    /**< static tables needed for computation */
  85
  86     Float11 sr[2];      /**< prev. reconstructed samples */
  87     Float11 dq[6];      /**< prev. difference */
  88     int a[2];           /**< second order predictor coeffs */
  89     int b[6];           /**< sixth order predictor coeffs */
  90     int pk[2];          /**< signs of prev. 2 sez + dq */
  91
  92     int ap;             /**< scale factor control */
  93     int yu;             /**< fast scale factor */
  94     int yl;             /**< slow scale factor */
  95     int dms;            /**< short average magnitude of F[i] */
  96     int dml;            /**< long average magnitude of F[i] */
  97     int td;             /**< tone detect */
  98
  99     int se;             /**< estimated signal for the next iteration */
 100     int sez;            /**< estimated second order prediction */
 101     int y;              /**< quantizer scaling factor for the next iteration */
 102     int code_size;
 103     int little_endian;  /**< little-endian bitstream as used in aiff and Sun AU */
 104 } G726Context;
 105
 106 static const int quant_tbl16[] =                  /**< 16kbit/s 2 bits per sample */
 107            { 260, INT_MAX };
 108 static const int16_t iquant_tbl16[] =
 109            { 116, 365, 365, 116 };
 110 static const int16_t W_tbl16[] =
 111            { -22, 439, 439, -22 };
 112 static const uint8_t F_tbl16[] =
 113            { 0, 7, 7, 0 };
 114
 115 static const int quant_tbl24[] =                  /**< 24kbit/s 3 bits per sample */
 116            {  7, 217, 330, INT_MAX };
 117 static const int16_t iquant_tbl24[] =
 118            { INT16_MIN, 135, 273, 373, 373, 273, 135, INT16_MIN };
 119 static const int16_t W_tbl24[] =
 120            { -4,  30, 137, 582, 582, 137,  30, -4 };
 121 static const uint8_t F_tbl24[] =
 122            { 0, 1, 2, 7, 7, 2, 1, 0 };
 123
 124 static const int quant_tbl32[] =                  /**< 32kbit/s 4 bits per sample */
 125            { -125,  79, 177, 245, 299, 348, 399, INT_MAX };
 126 static const int16_t iquant_tbl32[] =
 127          { INT16_MIN,   4, 135, 213, 273, 323, 373, 425,
 128                  425, 373, 323, 273, 213, 135,   4, INT16_MIN };
 129 static const int16_t W_tbl32[] =
 130            { -12,  18,  41,  64, 112, 198, 355, 1122,
 131             1122, 355, 198, 112,  64,  41,  18, -12};
 132 static const uint8_t F_tbl32[] =
 133            { 0, 0, 0, 1, 1, 1, 3, 7, 7, 3, 1, 1, 1, 0, 0, 0 };
 134
 135 static const int quant_tbl40[] =                  /**< 40kbit/s 5 bits per sample */
 136            { -122, -16,  67, 138, 197, 249, 297, 338,
 137               377, 412, 444, 474, 501, 527, 552, INT_MAX };
 138 static const int16_t iquant_tbl40[] =
 139          { INT16_MIN, -66,  28, 104, 169, 224, 274, 318,
 140                  358, 395, 429, 459, 488, 514, 539, 566,
 141                  566, 539, 514, 488, 459, 429, 395, 358,
 142                  318, 274, 224, 169, 104,  28, -66, INT16_MIN };
 143 static const int16_t W_tbl40[] =
 144            {   14,  14,  24,  39,  40,  41,   58,  100,
 145               141, 179, 219, 280, 358, 440,  529,  696,
 146               696, 529, 440, 358, 280, 219,  179,  141,
 147               100,  58,  41,  40,  39,  24,   14,   14 };
 148 static const uint8_t F_tbl40[] =
 149            { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 6,
 150              6, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
 151
 152 static const G726Tables G726Tables_pool[] =
 153            {{ quant_tbl16, iquant_tbl16, W_tbl16, F_tbl16 },
 154             { quant_tbl24, iquant_tbl24, W_tbl24, F_tbl24 },
 155             { quant_tbl32, iquant_tbl32, W_tbl32, F_tbl32 },
 156             { quant_tbl40, iquant_tbl40, W_tbl40, F_tbl40 }};
 157
 158
 159 /**
 160  * Paragraph 4.2.2 page 18: Adaptive quantizer.
 161  */
 162 static inline uint8_t quant(G726Context* c, int d)
 163 {
 164     int sign, exp, i, dln;
 165
 166     sign = i = 0;
 167     if (d < 0) {
 168         sign = 1;
 169         d = -d;
 170     }
 171     exp = av_log2_16bit(d);
 172     dln = ((exp<<7) + (((d<<7)>>exp)&0x7f)) - (c->y>>2);
 173
 174     while (c->tbls.quant[i] < INT_MAX && c->tbls.quant[i] < dln)
 175         ++i;
 176
 177     if (sign)
 178         i = ~i;
 179     if (c->code_size != 2 && i == 0) /* I'm not sure this is a good idea */
 180         i = 0xff;
 181
 182     return i;
 183 }
 184
 185 /**
 186  * Paragraph 4.2.3 page 22: Inverse adaptive quantizer.
 187  */
 188 static inline int16_t inverse_quant(G726Context* c, int i)
 189 {
 190     int dql, dex, dqt;
 191
 192     dql = c->tbls.iquant[i] + (c->y >> 2);
 193     dex = (dql>>7) & 0xf;        /* 4-bit exponent */
 194     dqt = (1<<7) + (dql & 0x7f); /* log2 -> linear */
 195     return (dql < 0) ? 0 : ((dqt<<dex) >> 7);
 196 }
 197
 198 static int16_t g726_decode(G726Context* c, int I)
 199 {
 200     int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0;
 201     Float11 f;
 202     int I_sig= I >> (c->code_size - 1);
 203
 204     dq = inverse_quant(c, I);
 205
 206     /* Transition detect */
 207     ylint = (c->yl >> 15);
 208     ylfrac = (c->yl >> 10) & 0x1f;
 209     thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint;
 210     tr= (c->td == 1 && dq > ((3*thr2)>>2));
 211
 212     if (I_sig)  /* get the sign */
 213         dq = -dq;
 214     re_signal = (int16_t)(c->se + dq);
 215
 216     /* Update second order predictor coefficient A2 and A1 */
 217     pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0;
 218     dq0 = dq ? sgn(dq) : 0;
 219     if (tr) {
 220         c->a[0] = 0;
 221         c->a[1] = 0;
 222         for (i=0; i<6; i++)
 223             c->b[i] = 0;
 224     } else {
 225         /* This is a bit crazy, but it really is +255 not +256 */
 226         fa1 = av_clip_intp2((-c->a[0]*c->pk[0]*pk0)>>5, 8);
 227
 228         c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7);
 229         c->a[1] = av_clip(c->a[1], -12288, 12288);
 230         c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8);
 231         c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]);
 232
 233         for (i=0; i<6; i++)
 234             c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8);
 235     }
 236
 237     /* Update Dq and Sr and Pk */
 238     c->pk[1] = c->pk[0];
 239     c->pk[0] = pk0 ? pk0 : 1;
 240     c->sr[1] = c->sr[0];
 241     i2f(re_signal, &c->sr[0]);
 242     for (i=5; i>0; i--)
 243         c->dq[i] = c->dq[i-1];
 244     i2f(dq, &c->dq[0]);
 245     c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */
 246
 247     c->td = c->a[1] < -11776;
 248
 249     /* Update Ap */
 250     c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5);
 251     c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7);
 252     if (tr)
 253         c->ap = 256;
 254     else {
 255         c->ap += (-c->ap) >> 4;
 256         if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3))
 257             c->ap += 0x20;
 258     }
 259
 260     /* Update Yu and Yl */
 261     c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120);
 262     c->yl += c->yu + ((-c->yl)>>6);
 263
 264     /* Next iteration for Y */
 265     al = (c->ap >= 256) ? 1<<6 : c->ap >> 2;
 266     c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6;
 267
 268     /* Next iteration for SE and SEZ */
 269     c->se = 0;
 270     for (i=0; i<6; i++)
 271         c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]);
 272     c->sez = c->se >> 1;
 273     for (i=0; i<2; i++)
 274         c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]);
 275     c->se >>= 1;
 276
 277     return av_clip(re_signal * 4, -0xffff, 0xffff);
 278 }
 279
 280 static av_cold int g726_reset(G726Context *c)
 281 {
 282     int i;
 283
 284     c->tbls = G726Tables_pool[c->code_size - 2];
 285     for (i=0; i<2; i++) {
 286         c->sr[i].mant = 1<<5;
 287         c->pk[i] = 1;
 288     }
 289     for (i=0; i<6; i++) {
 290         c->dq[i].mant = 1<<5;
 291     }
 292     c->yu = 544;
 293     c->yl = 34816;
 294
 295     c->y = 544;
 296
 297     return 0;
 298 }
 299
 300 #if CONFIG_ADPCM_G726_ENCODER || CONFIG_ADPCM_G726LE_ENCODER
 301 static int16_t g726_encode(G726Context* c, int16_t sig)
 302 {
 303     uint8_t i;
 304
 305     i = av_zero_extend(quant(c, sig/4 - c->se), c->code_size);
 306     g726_decode(c, i);
 307     return i;
 308 }
 309
 310 /* Interfacing to the libavcodec */
 311
 312 static av_cold int g726_encode_init(AVCodecContext *avctx)
 313 {
 314     G726Context* c = avctx->priv_data;
 315
 316     c->little_endian = !strcmp(avctx->codec->name, "g726le");
 317
 318     if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL &&
 319         avctx->sample_rate != 8000) {
 320         av_log(avctx, AV_LOG_ERROR, "Sample rates other than 8kHz are not "
 321                "allowed when the compliance level is higher than unofficial. "
 322                "Resample or reduce the compliance level.\n");
 323         return AVERROR(EINVAL);
 324     }
 325     if (avctx->sample_rate <= 0) {
 326         av_log(avctx, AV_LOG_ERROR, "Invalid sample rate %d\n",
 327                avctx->sample_rate);
 328         return AVERROR(EINVAL);
 329     }
 330
 331     if (avctx->ch_layout.nb_channels != 1) {
 332         av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n");
 333         return AVERROR(EINVAL);
 334     }
 335
 336     if (avctx->bit_rate)
 337         c->code_size = (avctx->bit_rate + avctx->sample_rate/2) / avctx->sample_rate;
 338
 339     c->code_size = av_clip(c->code_size, 2, 5);
 340     avctx->bit_rate = c->code_size * avctx->sample_rate;
 341     avctx->bits_per_coded_sample = c->code_size;
 342
 343     g726_reset(c);
 344
 345     /* select a frame size that will end on a byte boundary and have a size of
 346        approximately 1024 bytes */
 347     avctx->frame_size = ((int[]){ 4096, 2736, 2048, 1640 })[c->code_size - 2];
 348
 349     return 0;
 350 }
 351
 352 static int g726_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
 353                              const AVFrame *frame, int *got_packet_ptr)
 354 {
 355     G726Context *c = avctx->priv_data;
 356     const int16_t *samples = (const int16_t *)frame->data[0];
 357     PutBitContext pb;
 358     int i, ret, out_size;
 359
 360     out_size = (frame->nb_samples * c->code_size + 7) / 8;
 361     if ((ret = ff_get_encode_buffer(avctx, avpkt, out_size, 0)) < 0)
 362         return ret;
 363     init_put_bits(&pb, avpkt->data, avpkt->size);
 364
 365     for (i = 0; i < frame->nb_samples; i++)
 366         if (c->little_endian) {
 367             put_bits_le(&pb, c->code_size, g726_encode(c, *samples++));
 368         } else {
 369             put_bits(&pb, c->code_size, g726_encode(c, *samples++));
 370         }
 371
 372     if (c->little_endian) {
 373         flush_put_bits_le(&pb);
 374     } else {
 375         flush_put_bits(&pb);
 376     }
 377
 378     *got_packet_ptr = 1;
 379     return 0;
 380 }
 381
 382 #define OFFSET(x) offsetof(G726Context, x)
 383 #define AE AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 384 static const AVOption options[] = {
 385     { "code_size", "Bits per code", OFFSET(code_size), AV_OPT_TYPE_INT, { .i64 = 4 }, 2, 5, AE },
 386     { NULL },
 387 };
 388
 389 static const AVClass g726_class = {
 390     .class_name = "g726",
 391     .item_name  = av_default_item_name,
 392     .option     = options,
 393     .version    = LIBAVUTIL_VERSION_INT,
 394 };
 395
 396 static const FFCodecDefault defaults[] = {
 397     { "b", "0" },
 398     { NULL },
 399 };
 400 #endif
 401
 402 #if CONFIG_ADPCM_G726_ENCODER
 403 const FFCodec ff_adpcm_g726_encoder = {
 404     .p.name         = "g726",
 405     CODEC_LONG_NAME("G.726 ADPCM"),
 406     .p.type         = AVMEDIA_TYPE_AUDIO,
 407     .p.id           = AV_CODEC_ID_ADPCM_G726,
 408     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_SMALL_LAST_FRAME |
 409                       AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
 410     .priv_data_size = sizeof(G726Context),
 411     .init           = g726_encode_init,
 412     FF_CODEC_ENCODE_CB(g726_encode_frame),
 413     .p.sample_fmts  = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
 414                                                      AV_SAMPLE_FMT_NONE },
 415     .p.priv_class   = &g726_class,
 416     .defaults       = defaults,
 417 };
 418 #endif
 419
 420 #if CONFIG_ADPCM_G726LE_ENCODER
 421 const FFCodec ff_adpcm_g726le_encoder = {
 422     .p.name         = "g726le",
 423     CODEC_LONG_NAME("G.726 little endian ADPCM (\"right-justified\")"),
 424     .p.type         = AVMEDIA_TYPE_AUDIO,
 425     .p.id           = AV_CODEC_ID_ADPCM_G726LE,
 426     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_SMALL_LAST_FRAME |
 427                       AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
 428     .priv_data_size = sizeof(G726Context),
 429     .init           = g726_encode_init,
 430     FF_CODEC_ENCODE_CB(g726_encode_frame),
 431     .p.sample_fmts  = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
 432                                                      AV_SAMPLE_FMT_NONE },
 433     .p.priv_class   = &g726_class,
 434     .defaults       = defaults,
 435 };
 436 #endif
 437
 438 #if CONFIG_ADPCM_G726_DECODER || CONFIG_ADPCM_G726LE_DECODER
 439 static av_cold int g726_decode_init(AVCodecContext *avctx)
 440 {
 441     G726Context* c = avctx->priv_data;
 442
 443     if (avctx->ch_layout.nb_channels > 1){
 444         avpriv_request_sample(avctx, "Decoding more than one channel");
 445         return AVERROR_PATCHWELCOME;
 446     }
 447     av_channel_layout_uninit(&avctx->ch_layout);
 448     avctx->ch_layout      = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
 449
 450     c->little_endian = !strcmp(avctx->codec->name, "g726le");
 451
 452     c->code_size = avctx->bits_per_coded_sample;
 453     if (c->code_size < 2 || c->code_size > 5) {
 454         av_log(avctx, AV_LOG_ERROR, "Invalid number of bits %d\n", c->code_size);
 455         return AVERROR(EINVAL);
 456     }
 457     g726_reset(c);
 458
 459     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
 460
 461     return 0;
 462 }
 463
 464 static int g726_decode_frame(AVCodecContext *avctx, AVFrame *frame,
 465                              int *got_frame_ptr, AVPacket *avpkt)
 466 {
 467     const uint8_t *buf = avpkt->data;
 468     int buf_size = avpkt->size;
 469     G726Context *c = avctx->priv_data;
 470     int16_t *samples;
 471     GetBitContext gb;
 472     int out_samples, ret;
 473
 474     out_samples = buf_size * 8 / c->code_size;
 475
 476     /* get output buffer */
 477     frame->nb_samples = out_samples;
 478     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 479         return ret;
 480     samples = (int16_t *)frame->data[0];
 481
 482     init_get_bits(&gb, buf, buf_size * 8);
 483
 484     while (out_samples--)
 485         *samples++ = g726_decode(c, c->little_endian ?
 486                                     get_bits_le(&gb, c->code_size) :
 487                                     get_bits(&gb, c->code_size));
 488
 489     if (get_bits_left(&gb) > 0)
 490         av_log(avctx, AV_LOG_ERROR, "Frame invalidly split, missing parser?\n");
 491
 492     *got_frame_ptr = 1;
 493
 494     return buf_size;
 495 }
 496
 497 static void g726_decode_flush(AVCodecContext *avctx)
 498 {
 499     G726Context *c = avctx->priv_data;
 500     g726_reset(c);
 501 }
 502 #endif
 503
 504 #if CONFIG_ADPCM_G726_DECODER
 505 const FFCodec ff_adpcm_g726_decoder = {
 506     .p.name         = "g726",
 507     CODEC_LONG_NAME("G.726 ADPCM"),
 508     .p.type         = AVMEDIA_TYPE_AUDIO,
 509     .p.id           = AV_CODEC_ID_ADPCM_G726,
 510     .priv_data_size = sizeof(G726Context),
 511     .init           = g726_decode_init,
 512     FF_CODEC_DECODE_CB(g726_decode_frame),
 513     .flush          = g726_decode_flush,
 514     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
 515 };
 516 #endif
 517
 518 #if CONFIG_ADPCM_G726LE_DECODER
 519 const FFCodec ff_adpcm_g726le_decoder = {
 520     .p.name         = "g726le",
 521     .p.type         = AVMEDIA_TYPE_AUDIO,
 522     .p.id           = AV_CODEC_ID_ADPCM_G726LE,
 523     .priv_data_size = sizeof(G726Context),
 524     .init           = g726_decode_init,
 525     FF_CODEC_DECODE_CB(g726_decode_frame),
 526     .flush          = g726_decode_flush,
 527     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
 528     CODEC_LONG_NAME("G.726 ADPCM little-endian"),
 529 };
 530 #endif