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 Libav. 9 * 10 * Libav 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 * Libav 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 Libav; if not, write to the Free Software 22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 23 */ 24#include <limits.h> 25#include "libavutil/avassert.h" 26#include "libavutil/opt.h" 27#include "avcodec.h" 28#include "internal.h" 29#include "get_bits.h" 30#include "put_bits.h" 31 32/** 33 * G.726 11bit float. 34 * G.726 Standard uses rather odd 11bit floating point arithmentic for 35 * numerous occasions. It's a mistery to me why they did it this way 36 * instead of simply using 32bit integer arithmetic. 37 */ 38typedef struct Float11 { 39 uint8_t sign; /**< 1bit sign */ 40 uint8_t exp; /**< 4bit exponent */ 41 uint8_t mant; /**< 6bit mantissa */ 42} Float11; 43 44static inline Float11* i2f(int i, Float11* f) 45{ 46 f->sign = (i < 0); 47 if (f->sign) 48 i = -i; 49 f->exp = av_log2_16bit(i) + !!i; 50 f->mant = i? (i<<6) >> f->exp : 1<<5; 51 return f; 52} 53 54static inline int16_t mult(Float11* f1, Float11* f2) 55{ 56 int res, exp; 57 58 exp = f1->exp + f2->exp; 59 res = (((f1->mant * f2->mant) + 0x30) >> 4); 60 res = exp > 19 ? res << (exp - 19) : res >> (19 - exp); 61 return (f1->sign ^ f2->sign) ? -res : res; 62} 63 64static inline int sgn(int value) 65{ 66 return (value < 0) ? -1 : 1; 67} 68 69typedef struct G726Tables { 70 const int* quant; /**< quantization table */ 71 const int16_t* iquant; /**< inverse quantization table */ 72 const int16_t* W; /**< special table #1 ;-) */ 73 const uint8_t* F; /**< special table #2 */ 74} G726Tables; 75 76typedef struct G726Context { 77 AVClass *class; 78 AVFrame frame; 79 G726Tables tbls; /**< static tables needed for computation */ 80 81 Float11 sr[2]; /**< prev. reconstructed samples */ 82 Float11 dq[6]; /**< prev. difference */ 83 int a[2]; /**< second order predictor coeffs */ 84 int b[6]; /**< sixth order predictor coeffs */ 85 int pk[2]; /**< signs of prev. 2 sez + dq */ 86 87 int ap; /**< scale factor control */ 88 int yu; /**< fast scale factor */ 89 int yl; /**< slow scale factor */ 90 int dms; /**< short average magnitude of F[i] */ 91 int dml; /**< long average magnitude of F[i] */ 92 int td; /**< tone detect */ 93 94 int se; /**< estimated signal for the next iteration */ 95 int sez; /**< estimated second order prediction */ 96 int y; /**< quantizer scaling factor for the next iteration */ 97 int code_size; 98} G726Context; 99 100static const int quant_tbl16[] = /**< 16kbit/s 2bits per sample */ 101 { 260, INT_MAX }; 102static const int16_t iquant_tbl16[] = 103 { 116, 365, 365, 116 }; 104static const int16_t W_tbl16[] = 105 { -22, 439, 439, -22 }; 106static const uint8_t F_tbl16[] = 107 { 0, 7, 7, 0 }; 108 109static const int quant_tbl24[] = /**< 24kbit/s 3bits per sample */ 110 { 7, 217, 330, INT_MAX }; 111static const int16_t iquant_tbl24[] = 112 { INT16_MIN, 135, 273, 373, 373, 273, 135, INT16_MIN }; 113static const int16_t W_tbl24[] = 114 { -4, 30, 137, 582, 582, 137, 30, -4 }; 115static const uint8_t F_tbl24[] = 116 { 0, 1, 2, 7, 7, 2, 1, 0 }; 117 118static const int quant_tbl32[] = /**< 32kbit/s 4bits per sample */ 119 { -125, 79, 177, 245, 299, 348, 399, INT_MAX }; 120static const int16_t iquant_tbl32[] = 121 { INT16_MIN, 4, 135, 213, 273, 323, 373, 425, 122 425, 373, 323, 273, 213, 135, 4, INT16_MIN }; 123static const int16_t W_tbl32[] = 124 { -12, 18, 41, 64, 112, 198, 355, 1122, 125 1122, 355, 198, 112, 64, 41, 18, -12}; 126static const uint8_t F_tbl32[] = 127 { 0, 0, 0, 1, 1, 1, 3, 7, 7, 3, 1, 1, 1, 0, 0, 0 }; 128 129static const int quant_tbl40[] = /**< 40kbit/s 5bits per sample */ 130 { -122, -16, 67, 138, 197, 249, 297, 338, 131 377, 412, 444, 474, 501, 527, 552, INT_MAX }; 132static const int16_t iquant_tbl40[] = 133 { INT16_MIN, -66, 28, 104, 169, 224, 274, 318, 134 358, 395, 429, 459, 488, 514, 539, 566, 135 566, 539, 514, 488, 459, 429, 395, 358, 136 318, 274, 224, 169, 104, 28, -66, INT16_MIN }; 137static const int16_t W_tbl40[] = 138 { 14, 14, 24, 39, 40, 41, 58, 100, 139 141, 179, 219, 280, 358, 440, 529, 696, 140 696, 529, 440, 358, 280, 219, 179, 141, 141 100, 58, 41, 40, 39, 24, 14, 14 }; 142static const uint8_t F_tbl40[] = 143 { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 6, 144 6, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 }; 145 146static const G726Tables G726Tables_pool[] = 147 {{ quant_tbl16, iquant_tbl16, W_tbl16, F_tbl16 }, 148 { quant_tbl24, iquant_tbl24, W_tbl24, F_tbl24 }, 149 { quant_tbl32, iquant_tbl32, W_tbl32, F_tbl32 }, 150 { quant_tbl40, iquant_tbl40, W_tbl40, F_tbl40 }}; 151 152 153/** 154 * Para 4.2.2 page 18: Adaptive quantizer. 155 */ 156static inline uint8_t quant(G726Context* c, int d) 157{ 158 int sign, exp, i, dln; 159 160 sign = i = 0; 161 if (d < 0) { 162 sign = 1; 163 d = -d; 164 } 165 exp = av_log2_16bit(d); 166 dln = ((exp<<7) + (((d<<7)>>exp)&0x7f)) - (c->y>>2); 167 168 while (c->tbls.quant[i] < INT_MAX && c->tbls.quant[i] < dln) 169 ++i; 170 171 if (sign) 172 i = ~i; 173 if (c->code_size != 2 && i == 0) /* I'm not sure this is a good idea */ 174 i = 0xff; 175 176 return i; 177} 178 179/** 180 * Para 4.2.3 page 22: Inverse adaptive quantizer. 181 */ 182static inline int16_t inverse_quant(G726Context* c, int i) 183{ 184 int dql, dex, dqt; 185 186 dql = c->tbls.iquant[i] + (c->y >> 2); 187 dex = (dql>>7) & 0xf; /* 4bit exponent */ 188 dqt = (1<<7) + (dql & 0x7f); /* log2 -> linear */ 189 return (dql < 0) ? 0 : ((dqt<<dex) >> 7); 190} 191 192static int16_t g726_decode(G726Context* c, int I) 193{ 194 int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0; 195 Float11 f; 196 int I_sig= I >> (c->code_size - 1); 197 198 dq = inverse_quant(c, I); 199 200 /* Transition detect */ 201 ylint = (c->yl >> 15); 202 ylfrac = (c->yl >> 10) & 0x1f; 203 thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint; 204 tr= (c->td == 1 && dq > ((3*thr2)>>2)); 205 206 if (I_sig) /* get the sign */ 207 dq = -dq; 208 re_signal = c->se + dq; 209 210 /* Update second order predictor coefficient A2 and A1 */ 211 pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0; 212 dq0 = dq ? sgn(dq) : 0; 213 if (tr) { 214 c->a[0] = 0; 215 c->a[1] = 0; 216 for (i=0; i<6; i++) 217 c->b[i] = 0; 218 } else { 219 /* This is a bit crazy, but it really is +255 not +256 */ 220 fa1 = av_clip((-c->a[0]*c->pk[0]*pk0)>>5, -256, 255); 221 222 c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7); 223 c->a[1] = av_clip(c->a[1], -12288, 12288); 224 c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8); 225 c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]); 226 227 for (i=0; i<6; i++) 228 c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8); 229 } 230 231 /* Update Dq and Sr and Pk */ 232 c->pk[1] = c->pk[0]; 233 c->pk[0] = pk0 ? pk0 : 1; 234 c->sr[1] = c->sr[0]; 235 i2f(re_signal, &c->sr[0]); 236 for (i=5; i>0; i--) 237 c->dq[i] = c->dq[i-1]; 238 i2f(dq, &c->dq[0]); 239 c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */ 240 241 c->td = c->a[1] < -11776; 242 243 /* Update Ap */ 244 c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5); 245 c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7); 246 if (tr) 247 c->ap = 256; 248 else { 249 c->ap += (-c->ap) >> 4; 250 if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3)) 251 c->ap += 0x20; 252 } 253 254 /* Update Yu and Yl */ 255 c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120); 256 c->yl += c->yu + ((-c->yl)>>6); 257 258 /* Next iteration for Y */ 259 al = (c->ap >= 256) ? 1<<6 : c->ap >> 2; 260 c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6; 261 262 /* Next iteration for SE and SEZ */ 263 c->se = 0; 264 for (i=0; i<6; i++) 265 c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]); 266 c->sez = c->se >> 1; 267 for (i=0; i<2; i++) 268 c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]); 269 c->se >>= 1; 270 271 return av_clip(re_signal << 2, -0xffff, 0xffff); 272} 273 274static av_cold int g726_reset(G726Context *c) 275{ 276 int i; 277 278 c->tbls = G726Tables_pool[c->code_size - 2]; 279 for (i=0; i<2; i++) { 280 c->sr[i].mant = 1<<5; 281 c->pk[i] = 1; 282 } 283 for (i=0; i<6; i++) { 284 c->dq[i].mant = 1<<5; 285 } 286 c->yu = 544; 287 c->yl = 34816; 288 289 c->y = 544; 290 291 return 0; 292} 293 294#if CONFIG_ADPCM_G726_ENCODER 295static int16_t g726_encode(G726Context* c, int16_t sig) 296{ 297 uint8_t i; 298 299 i = quant(c, sig/4 - c->se) & ((1<<c->code_size) - 1); 300 g726_decode(c, i); 301 return i; 302} 303 304/* Interfacing to the libavcodec */ 305 306static av_cold int g726_encode_init(AVCodecContext *avctx) 307{ 308 G726Context* c = avctx->priv_data; 309 310 if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL && 311 avctx->sample_rate != 8000) { 312 av_log(avctx, AV_LOG_ERROR, "Sample rates other than 8kHz are not " 313 "allowed when the compliance level is higher than unofficial. " 314 "Resample or reduce the compliance level.\n"); 315 return AVERROR(EINVAL); 316 } 317 av_assert0(avctx->sample_rate > 0); 318 319 if(avctx->channels != 1){ 320 av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n"); 321 return AVERROR(EINVAL); 322 } 323 324 if (avctx->bit_rate) 325 c->code_size = (avctx->bit_rate + avctx->sample_rate/2) / avctx->sample_rate; 326 327 c->code_size = av_clip(c->code_size, 2, 5); 328 avctx->bit_rate = c->code_size * avctx->sample_rate; 329 avctx->bits_per_coded_sample = c->code_size; 330 331 g726_reset(c); 332 333 avctx->coded_frame = avcodec_alloc_frame(); 334 if (!avctx->coded_frame) 335 return AVERROR(ENOMEM); 336 avctx->coded_frame->key_frame = 1; 337 338 /* select a frame size that will end on a byte boundary and have a size of 339 approximately 1024 bytes */ 340 avctx->frame_size = ((int[]){ 4096, 2736, 2048, 1640 })[c->code_size - 2]; 341 342 return 0; 343} 344 345static av_cold int g726_encode_close(AVCodecContext *avctx) 346{ 347 av_freep(&avctx->coded_frame); 348 return 0; 349} 350 351static int g726_encode_frame(AVCodecContext *avctx, 352 uint8_t *dst, int buf_size, void *data) 353{ 354 G726Context *c = avctx->priv_data; 355 const int16_t *samples = data; 356 PutBitContext pb; 357 int i; 358 359 init_put_bits(&pb, dst, 1024*1024); 360 361 for (i = 0; i < avctx->frame_size; i++) 362 put_bits(&pb, c->code_size, g726_encode(c, *samples++)); 363 364 flush_put_bits(&pb); 365 366 return put_bits_count(&pb)>>3; 367} 368 369#define OFFSET(x) offsetof(G726Context, x) 370#define AE AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM 371static const AVOption options[] = { 372 { "code_size", "Bits per code", OFFSET(code_size), AV_OPT_TYPE_INT, { 4 }, 2, 5, AE }, 373 { NULL }, 374}; 375 376static const AVClass class = { 377 .class_name = "g726", 378 .item_name = av_default_item_name, 379 .option = options, 380 .version = LIBAVUTIL_VERSION_INT, 381}; 382 383static const AVCodecDefault defaults[] = { 384 { "b", "0" }, 385 { NULL }, 386}; 387 388AVCodec ff_adpcm_g726_encoder = { 389 .name = "g726", 390 .type = AVMEDIA_TYPE_AUDIO, 391 .id = CODEC_ID_ADPCM_G726, 392 .priv_data_size = sizeof(G726Context), 393 .init = g726_encode_init, 394 .encode = g726_encode_frame, 395 .close = g726_encode_close, 396 .capabilities = CODEC_CAP_SMALL_LAST_FRAME, 397 .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE}, 398 .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"), 399 .priv_class = &class, 400 .defaults = defaults, 401}; 402#endif 403 404#if CONFIG_ADPCM_G726_DECODER 405static av_cold int g726_decode_init(AVCodecContext *avctx) 406{ 407 G726Context* c = avctx->priv_data; 408 409 if (avctx->strict_std_compliance >= FF_COMPLIANCE_STRICT && 410 avctx->sample_rate != 8000) { 411 av_log(avctx, AV_LOG_ERROR, "Only 8kHz sample rate is allowed when " 412 "the compliance level is strict. Reduce the compliance level " 413 "if you wish to decode the stream anyway.\n"); 414 return AVERROR(EINVAL); 415 } 416 417 if(avctx->channels != 1){ 418 av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n"); 419 return AVERROR(EINVAL); 420 } 421 422 c->code_size = avctx->bits_per_coded_sample; 423 if (c->code_size < 2 || c->code_size > 5) { 424 av_log(avctx, AV_LOG_ERROR, "Invalid number of bits %d\n", c->code_size); 425 return AVERROR(EINVAL); 426 } 427 g726_reset(c); 428 429 avctx->sample_fmt = AV_SAMPLE_FMT_S16; 430 431 avcodec_get_frame_defaults(&c->frame); 432 avctx->coded_frame = &c->frame; 433 434 return 0; 435} 436 437static int g726_decode_frame(AVCodecContext *avctx, void *data, 438 int *got_frame_ptr, AVPacket *avpkt) 439{ 440 const uint8_t *buf = avpkt->data; 441 int buf_size = avpkt->size; 442 G726Context *c = avctx->priv_data; 443 int16_t *samples; 444 GetBitContext gb; 445 int out_samples, ret; 446 447 out_samples = buf_size * 8 / c->code_size; 448 449 /* get output buffer */ 450 c->frame.nb_samples = out_samples; 451 if ((ret = avctx->get_buffer(avctx, &c->frame)) < 0) { 452 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); 453 return ret; 454 } 455 samples = (int16_t *)c->frame.data[0]; 456 457 init_get_bits(&gb, buf, buf_size * 8); 458 459 while (out_samples--) 460 *samples++ = g726_decode(c, get_bits(&gb, c->code_size)); 461 462 if (get_bits_left(&gb) > 0) 463 av_log(avctx, AV_LOG_ERROR, "Frame invalidly split, missing parser?\n"); 464 465 *got_frame_ptr = 1; 466 *(AVFrame *)data = c->frame; 467 468 return buf_size; 469} 470 471static void g726_decode_flush(AVCodecContext *avctx) 472{ 473 G726Context *c = avctx->priv_data; 474 g726_reset(c); 475} 476 477AVCodec ff_adpcm_g726_decoder = { 478 .name = "g726", 479 .type = AVMEDIA_TYPE_AUDIO, 480 .id = CODEC_ID_ADPCM_G726, 481 .priv_data_size = sizeof(G726Context), 482 .init = g726_decode_init, 483 .decode = g726_decode_frame, 484 .flush = g726_decode_flush, 485 .capabilities = CODEC_CAP_DR1, 486 .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"), 487}; 488#endif 489