ffmpeg/libavcodec/opus.h

   1 /*
   2  * Opus decoder/demuxer common functions
   3  * Copyright (c) 2012 Andrew D'Addesio
   4  * Copyright (c) 2013-2014 Mozilla Corporation
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #ifndef AVCODEC_OPUS_H
  24 #define AVCODEC_OPUS_H
  25
  26 #include <stdint.h>
  27
  28 #include "libavutil/audio_fifo.h"
  29 #include "libavutil/float_dsp.h"
  30 #include "libavutil/frame.h"
  31
  32 #include "libswresample/swresample.h"
  33
  34 #include "avcodec.h"
  35 #include "get_bits.h"
  36
  37 #define MAX_FRAME_SIZE               1275
  38 #define MAX_FRAMES                   48
  39 #define MAX_PACKET_DUR               5760
  40
  41 #define CELT_SHORT_BLOCKSIZE         120
  42 #define CELT_OVERLAP                 CELT_SHORT_BLOCKSIZE
  43 #define CELT_MAX_LOG_BLOCKS          3
  44 #define CELT_MAX_FRAME_SIZE          (CELT_SHORT_BLOCKSIZE * (1 << CELT_MAX_LOG_BLOCKS))
  45 #define CELT_MAX_BANDS               21
  46 #define CELT_VECTORS                 11
  47 #define CELT_ALLOC_STEPS             6
  48 #define CELT_FINE_OFFSET             21
  49 #define CELT_MAX_FINE_BITS           8
  50 #define CELT_NORM_SCALE              16384
  51 #define CELT_QTHETA_OFFSET           4
  52 #define CELT_QTHETA_OFFSET_TWOPHASE  16
  53 #define CELT_DEEMPH_COEFF            0.85000610f
  54 #define CELT_POSTFILTER_MINPERIOD    15
  55 #define CELT_ENERGY_SILENCE          (-28.0f)
  56
  57 #define SILK_HISTORY                 322
  58 #define SILK_MAX_LPC                 16
  59
  60 #define ROUND_MULL(a,b,s) (((MUL64(a, b) >> ((s) - 1)) + 1) >> 1)
  61 #define ROUND_MUL16(a,b)  ((MUL16(a, b) + 16384) >> 15)
  62 #define opus_ilog(i) (av_log2(i) + !!(i))
  63
  64 #define OPUS_TS_HEADER     0x7FE0        // 0x3ff (11 bits)
  65 #define OPUS_TS_MASK       0xFFE0        // top 11 bits
  66
  67 static const uint8_t opus_default_extradata[30] = {
  68     'O', 'p', 'u', 's', 'H', 'e', 'a', 'd',
  69     1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  70     0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  71 };
  72
  73 enum OpusMode {
  74     OPUS_MODE_SILK,
  75     OPUS_MODE_HYBRID,
  76     OPUS_MODE_CELT
  77 };
  78
  79 enum OpusBandwidth {
  80     OPUS_BANDWIDTH_NARROWBAND,
  81     OPUS_BANDWIDTH_MEDIUMBAND,
  82     OPUS_BANDWIDTH_WIDEBAND,
  83     OPUS_BANDWIDTH_SUPERWIDEBAND,
  84     OPUS_BANDWIDTH_FULLBAND
  85 };
  86
  87 typedef struct RawBitsContext {
  88     const uint8_t *position;
  89     unsigned int bytes;
  90     unsigned int cachelen;
  91     unsigned int cacheval;
  92 } RawBitsContext;
  93
  94 typedef struct OpusRangeCoder {
  95     GetBitContext gb;
  96     RawBitsContext rb;
  97     unsigned int range;
  98     unsigned int value;
  99     unsigned int total_read_bits;
 100 } OpusRangeCoder;
 101
 102 typedef struct SilkContext SilkContext;
 103
 104 typedef struct CeltContext CeltContext;
 105
 106 typedef struct OpusPacket {
 107     int packet_size;                /**< packet size */
 108     int data_size;                  /**< size of the useful data -- packet size - padding */
 109     int code;                       /**< packet code: specifies the frame layout */
 110     int stereo;                     /**< whether this packet is mono or stereo */
 111     int vbr;                        /**< vbr flag */
 112     int config;                     /**< configuration: tells the audio mode,
 113                                      **                bandwidth, and frame duration */
 114     int frame_count;                /**< frame count */
 115     int frame_offset[MAX_FRAMES];   /**< frame offsets */
 116     int frame_size[MAX_FRAMES];     /**< frame sizes */
 117     int frame_duration;             /**< frame duration, in samples @ 48kHz */
 118     enum OpusMode mode;             /**< mode */
 119     enum OpusBandwidth bandwidth;   /**< bandwidth */
 120 } OpusPacket;
 121
 122 typedef struct OpusStreamContext {
 123     AVCodecContext *avctx;
 124     int output_channels;
 125
 126     OpusRangeCoder rc;
 127     OpusRangeCoder redundancy_rc;
 128     SilkContext *silk;
 129     CeltContext *celt;
 130     AVFloatDSPContext *fdsp;
 131
 132     float silk_buf[2][960];
 133     float *silk_output[2];
 134     DECLARE_ALIGNED(32, float, celt_buf)[2][960];
 135     float *celt_output[2];
 136
 137     float redundancy_buf[2][960];
 138     float *redundancy_output[2];
 139
 140     /* data buffers for the final output data */
 141     float *out[2];
 142     int out_size;
 143
 144     float *out_dummy;
 145     int    out_dummy_allocated_size;
 146
 147     SwrContext *swr;
 148     AVAudioFifo *celt_delay;
 149     int silk_samplerate;
 150     /* number of samples we still want to get from the resampler */
 151     int delayed_samples;
 152
 153     OpusPacket packet;
 154
 155     int redundancy_idx;
 156 } OpusStreamContext;
 157
 158 // a mapping between an opus stream and an output channel
 159 typedef struct ChannelMap {
 160     int stream_idx;
 161     int channel_idx;
 162
 163     // when a single decoded channel is mapped to multiple output channels, we
 164     // write to the first output directly and copy from it to the others
 165     // this field is set to 1 for those copied output channels
 166     int copy;
 167     // this is the index of the output channel to copy from
 168     int copy_idx;
 169
 170     // this channel is silent
 171     int silence;
 172 } ChannelMap;
 173
 174 typedef struct OpusContext {
 175     OpusStreamContext *streams;
 176     int             nb_streams;
 177     int      nb_stereo_streams;
 178
 179     AVFloatDSPContext *fdsp;
 180     int16_t gain_i;
 181     float   gain;
 182
 183     ChannelMap *channel_maps;
 184 } OpusContext;
 185
 186 static av_always_inline void opus_rc_normalize(OpusRangeCoder *rc)
 187 {
 188     while (rc->range <= 1<<23) {
 189         rc->value = ((rc->value << 8) | (get_bits(&rc->gb, 8) ^ 0xFF)) & ((1u << 31) - 1);
 190         rc->range          <<= 8;
 191         rc->total_read_bits += 8;
 192     }
 193 }
 194
 195 static av_always_inline void opus_rc_update(OpusRangeCoder *rc, unsigned int scale,
 196                                           unsigned int low, unsigned int high,
 197                                           unsigned int total)
 198 {
 199     rc->value -= scale * (total - high);
 200     rc->range  = low ? scale * (high - low)
 201                       : rc->range - scale * (total - high);
 202     opus_rc_normalize(rc);
 203 }
 204
 205 static av_always_inline unsigned int opus_rc_getsymbol(OpusRangeCoder *rc, const uint16_t *cdf)
 206 {
 207     unsigned int k, scale, total, symbol, low, high;
 208
 209     total = *cdf++;
 210
 211     scale   = rc->range / total;
 212     symbol = rc->value / scale + 1;
 213     symbol = total - FFMIN(symbol, total);
 214
 215     for (k = 0; cdf[k] <= symbol; k++);
 216     high = cdf[k];
 217     low  = k ? cdf[k-1] : 0;
 218
 219     opus_rc_update(rc, scale, low, high, total);
 220
 221     return k;
 222 }
 223
 224 static av_always_inline unsigned int opus_rc_p2model(OpusRangeCoder *rc, unsigned int bits)
 225 {
 226     unsigned int k, scale;
 227     scale = rc->range >> bits; // in this case, scale = symbol
 228
 229     if (rc->value >= scale) {
 230         rc->value -= scale;
 231         rc->range -= scale;
 232         k = 0;
 233     } else {
 234         rc->range = scale;
 235         k = 1;
 236     }
 237     opus_rc_normalize(rc);
 238     return k;
 239 }
 240
 241 /**
 242  * CELT: estimate bits of entropy that have thus far been consumed for the
 243  *       current CELT frame, to integer and fractional (1/8th bit) precision
 244  */
 245 static av_always_inline unsigned int opus_rc_tell(const OpusRangeCoder *rc)
 246 {
 247     return rc->total_read_bits - av_log2(rc->range) - 1;
 248 }
 249
 250 static av_always_inline unsigned int opus_rc_tell_frac(const OpusRangeCoder *rc)
 251 {
 252     unsigned int i, total_bits, rcbuffer, range;
 253
 254     total_bits = rc->total_read_bits << 3;
 255     rcbuffer   = av_log2(rc->range) + 1;
 256     range      = rc->range >> (rcbuffer-16);
 257
 258     for (i = 0; i < 3; i++) {
 259         int bit;
 260         range = range * range >> 15;
 261         bit = range >> 16;
 262         rcbuffer = rcbuffer << 1 | bit;
 263         range >>= bit;
 264     }
 265
 266     return total_bits - rcbuffer;
 267 }
 268
 269 /**
 270  * CELT: read 1-25 raw bits at the end of the frame, backwards byte-wise
 271  */
 272 static av_always_inline unsigned int opus_getrawbits(OpusRangeCoder *rc, unsigned int count)
 273 {
 274     unsigned int value = 0;
 275
 276     while (rc->rb.bytes && rc->rb.cachelen < count) {
 277         rc->rb.cacheval |= *--rc->rb.position << rc->rb.cachelen;
 278         rc->rb.cachelen += 8;
 279         rc->rb.bytes--;
 280     }
 281
 282     value = rc->rb.cacheval & ((1<<count)-1);
 283     rc->rb.cacheval    >>= count;
 284     rc->rb.cachelen     -= count;
 285     rc->total_read_bits += count;
 286
 287     return value;
 288 }
 289
 290 /**
 291  * CELT: read a uniform distribution
 292  */
 293 static av_always_inline unsigned int opus_rc_unimodel(OpusRangeCoder *rc, unsigned int size)
 294 {
 295     unsigned int bits, k, scale, total;
 296
 297     bits  = opus_ilog(size - 1);
 298     total = (bits > 8) ? ((size - 1) >> (bits - 8)) + 1 : size;
 299
 300     scale  = rc->range / total;
 301     k      = rc->value / scale + 1;
 302     k      = total - FFMIN(k, total);
 303     opus_rc_update(rc, scale, k, k + 1, total);
 304
 305     if (bits > 8) {
 306         k = k << (bits - 8) | opus_getrawbits(rc, bits - 8);
 307         return FFMIN(k, size - 1);
 308     } else
 309         return k;
 310 }
 311
 312 static av_always_inline int opus_rc_laplace(OpusRangeCoder *rc, unsigned int symbol, int decay)
 313 {
 314     /* extends the range coder to model a Laplace distribution */
 315     int value = 0;
 316     unsigned int scale, low = 0, center;
 317
 318     scale  = rc->range >> 15;
 319     center = rc->value / scale + 1;
 320     center = (1 << 15) - FFMIN(center, 1 << 15);
 321
 322     if (center >= symbol) {
 323         value++;
 324         low = symbol;
 325         symbol = 1 + ((32768 - 32 - symbol) * (16384-decay) >> 15);
 326
 327         while (symbol > 1 && center >= low + 2 * symbol) {
 328             value++;
 329             symbol *= 2;
 330             low    += symbol;
 331             symbol  = (((symbol - 2) * decay) >> 15) + 1;
 332         }
 333
 334         if (symbol <= 1) {
 335             int distance = (center - low) >> 1;
 336             value += distance;
 337             low   += 2 * distance;
 338         }
 339
 340         if (center < low + symbol)
 341             value *= -1;
 342         else
 343             low += symbol;
 344     }
 345
 346     opus_rc_update(rc, scale, low, FFMIN(low + symbol, 32768), 32768);
 347
 348     return value;
 349 }
 350
 351 static av_always_inline unsigned int opus_rc_stepmodel(OpusRangeCoder *rc, int k0)
 352 {
 353     /* Use a probability of 3 up to itheta=8192 and then use 1 after */
 354     unsigned int k, scale, symbol, total = (k0+1)*3 + k0;
 355     scale  = rc->range / total;
 356     symbol = rc->value / scale + 1;
 357     symbol = total - FFMIN(symbol, total);
 358
 359     k = (symbol < (k0+1)*3) ? symbol/3 : symbol - (k0+1)*2;
 360
 361     opus_rc_update(rc, scale, (k <= k0) ? 3*(k+0) : (k-1-k0) + 3*(k0+1),
 362                    (k <= k0) ? 3*(k+1) : (k-0-k0) + 3*(k0+1), total);
 363     return k;
 364 }
 365
 366 static av_always_inline unsigned int opus_rc_trimodel(OpusRangeCoder *rc, int qn)
 367 {
 368     unsigned int k, scale, symbol, total, low, center;
 369
 370     total = ((qn>>1) + 1) * ((qn>>1) + 1);
 371     scale   = rc->range / total;
 372     center = rc->value / scale + 1;
 373     center = total - FFMIN(center, total);
 374
 375     if (center < total >> 1) {
 376         k      = (ff_sqrt(8 * center + 1) - 1) >> 1;
 377         low    = k * (k + 1) >> 1;
 378         symbol = k + 1;
 379     } else {
 380         k      = (2*(qn + 1) - ff_sqrt(8*(total - center - 1) + 1)) >> 1;
 381         low    = total - ((qn + 1 - k) * (qn + 2 - k) >> 1);
 382         symbol = qn + 1 - k;
 383     }
 384
 385     opus_rc_update(rc, scale, low, low + symbol, total);
 386
 387     return k;
 388 }
 389
 390 int ff_opus_parse_packet(OpusPacket *pkt, const uint8_t *buf, int buf_size,
 391                          int self_delimited);
 392
 393 int ff_opus_parse_extradata(AVCodecContext *avctx, OpusContext *s);
 394
 395 int ff_silk_init(AVCodecContext *avctx, SilkContext **ps, int output_channels);
 396 void ff_silk_free(SilkContext **ps);
 397 void ff_silk_flush(SilkContext *s);
 398
 399 /**
 400  * Decode the LP layer of one Opus frame (which may correspond to several SILK
 401  * frames).
 402  */
 403 int ff_silk_decode_superframe(SilkContext *s, OpusRangeCoder *rc,
 404                               float *output[2],
 405                               enum OpusBandwidth bandwidth, int coded_channels,
 406                               int duration_ms);
 407
 408 int ff_celt_init(AVCodecContext *avctx, CeltContext **s, int output_channels);
 409
 410 void ff_celt_free(CeltContext **s);
 411
 412 void ff_celt_flush(CeltContext *s);
 413
 414 int ff_celt_decode_frame(CeltContext *s, OpusRangeCoder *rc,
 415                          float **output, int coded_channels, int frame_size,
 416                          int startband,  int endband);
 417
 418 extern const float ff_celt_window2[120];
 419
 420 #endif /* AVCODEC_OPUS_H */