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opus.h
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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 
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 {
77 };
78 
85 };
86 
87 typedef struct RawBitsContext {
88  const uint8_t *position;
89  unsigned int bytes;
90  unsigned int cachelen;
91  unsigned int cacheval;
93 
94 typedef struct OpusRangeCoder {
97  unsigned int range;
98  unsigned int value;
99  unsigned int total_read_bits;
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 {
125 
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;
146 
150  /* number of samples we still want to get from the resampler */
152 
154 
157 
158 // a mapping between an opus stream and an output channel
159 typedef struct ChannelMap {
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 {
178 
180  int16_t gain_i;
181  float gain;
182 
184 } OpusContext;
185 
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 
394 
395 int ff_silk_init(AVCodecContext *avctx, SilkContext **ps, int output_channels);
396 void ff_silk_free(SilkContext **ps);
398 
399 /**
400  * Decode the LP layer of one Opus frame (which may correspond to several SILK
401  * frames).
402  */
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 
413 
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 */