summaryrefslogtreecommitdiff
path: root/libavcodec/opus.h
blob: 92bb28a371dbf3dabb5f0e4ed248917bdf184890 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
/*
 * Opus decoder/demuxer common functions
 * Copyright (c) 2012 Andrew D'Addesio
 * Copyright (c) 2013-2014 Mozilla Corporation
 *
 * 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
 */

#ifndef AVCODEC_OPUS_H
#define AVCODEC_OPUS_H

#include <stdint.h>

#include "libavutil/audio_fifo.h"
#include "libavutil/float_dsp.h"
#include "libavutil/frame.h"

#include "libswresample/swresample.h"

#include "avcodec.h"
#include "get_bits.h"

#define MAX_FRAME_SIZE               1275
#define MAX_FRAMES                   48
#define MAX_PACKET_DUR               5760

#define CELT_SHORT_BLOCKSIZE         120
#define CELT_OVERLAP                 CELT_SHORT_BLOCKSIZE
#define CELT_MAX_LOG_BLOCKS          3
#define CELT_MAX_FRAME_SIZE          (CELT_SHORT_BLOCKSIZE * (1 << CELT_MAX_LOG_BLOCKS))
#define CELT_MAX_BANDS               21
#define CELT_VECTORS                 11
#define CELT_ALLOC_STEPS             6
#define CELT_FINE_OFFSET             21
#define CELT_MAX_FINE_BITS           8
#define CELT_NORM_SCALE              16384
#define CELT_QTHETA_OFFSET           4
#define CELT_QTHETA_OFFSET_TWOPHASE  16
#define CELT_DEEMPH_COEFF            0.85000610f
#define CELT_POSTFILTER_MINPERIOD    15
#define CELT_ENERGY_SILENCE          (-28.0f)

#define SILK_HISTORY                 322
#define SILK_MAX_LPC                 16

#define ROUND_MULL(a,b,s) (((MUL64(a, b) >> ((s) - 1)) + 1) >> 1)
#define ROUND_MUL16(a,b)  ((MUL16(a, b) + 16384) >> 15)
#define opus_ilog(i) (av_log2(i) + !!(i))

#define OPUS_TS_HEADER     0x7FE0        // 0x3ff (11 bits)
#define OPUS_TS_MASK       0xFFE0        // top 11 bits

static const uint8_t opus_default_extradata[30] = {
    'O', 'p', 'u', 's', 'H', 'e', 'a', 'd',
    1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};

enum OpusMode {
    OPUS_MODE_SILK,
    OPUS_MODE_HYBRID,
    OPUS_MODE_CELT
};

enum OpusBandwidth {
    OPUS_BANDWIDTH_NARROWBAND,
    OPUS_BANDWIDTH_MEDIUMBAND,
    OPUS_BANDWIDTH_WIDEBAND,
    OPUS_BANDWIDTH_SUPERWIDEBAND,
    OPUS_BANDWIDTH_FULLBAND
};

typedef struct RawBitsContext {
    const uint8_t *position;
    unsigned int bytes;
    unsigned int cachelen;
    unsigned int cacheval;
} RawBitsContext;

typedef struct OpusRangeCoder {
    GetBitContext gb;
    RawBitsContext rb;
    unsigned int range;
    unsigned int value;
    unsigned int total_read_bits;
} OpusRangeCoder;

typedef struct SilkContext SilkContext;

typedef struct CeltContext CeltContext;

typedef struct OpusPacket {
    int packet_size;                /**< packet size */
    int data_size;                  /**< size of the useful data -- packet size - padding */
    int code;                       /**< packet code: specifies the frame layout */
    int stereo;                     /**< whether this packet is mono or stereo */
    int vbr;                        /**< vbr flag */
    int config;                     /**< configuration: tells the audio mode,
                                     **                bandwidth, and frame duration */
    int frame_count;                /**< frame count */
    int frame_offset[MAX_FRAMES];   /**< frame offsets */
    int frame_size[MAX_FRAMES];     /**< frame sizes */
    int frame_duration;             /**< frame duration, in samples @ 48kHz */
    enum OpusMode mode;             /**< mode */
    enum OpusBandwidth bandwidth;   /**< bandwidth */
} OpusPacket;

typedef struct OpusStreamContext {
    AVCodecContext *avctx;
    int output_channels;

    OpusRangeCoder rc;
    OpusRangeCoder redundancy_rc;
    SilkContext *silk;
    CeltContext *celt;
    AVFloatDSPContext *fdsp;

    float silk_buf[2][960];
    float *silk_output[2];
    DECLARE_ALIGNED(32, float, celt_buf)[2][960];
    float *celt_output[2];

    float redundancy_buf[2][960];
    float *redundancy_output[2];

    /* data buffers for the final output data */
    float *out[2];
    int out_size;

    float *out_dummy;
    int    out_dummy_allocated_size;

    SwrContext *swr;
    AVAudioFifo *celt_delay;
    int silk_samplerate;
    /* number of samples we still want to get from the resampler */
    int delayed_samples;

    OpusPacket packet;

    int redundancy_idx;
} OpusStreamContext;

// a mapping between an opus stream and an output channel
typedef struct ChannelMap {
    int stream_idx;
    int channel_idx;

    // when a single decoded channel is mapped to multiple output channels, we
    // write to the first output directly and copy from it to the others
    // this field is set to 1 for those copied output channels
    int copy;
    // this is the index of the output channel to copy from
    int copy_idx;

    // this channel is silent
    int silence;
} ChannelMap;

typedef struct OpusContext {
    OpusStreamContext *streams;
    int             nb_streams;
    int      nb_stereo_streams;

    AVFloatDSPContext *fdsp;
    int16_t gain_i;
    float   gain;

    ChannelMap *channel_maps;
} OpusContext;

static av_always_inline void opus_rc_normalize(OpusRangeCoder *rc)
{
    while (rc->range <= 1<<23) {
        rc->value = ((rc->value << 8) | (get_bits(&rc->gb, 8) ^ 0xFF)) & ((1u << 31) - 1);
        rc->range          <<= 8;
        rc->total_read_bits += 8;
    }
}

static av_always_inline void opus_rc_update(OpusRangeCoder *rc, unsigned int scale,
                                          unsigned int low, unsigned int high,
                                          unsigned int total)
{
    rc->value -= scale * (total - high);
    rc->range  = low ? scale * (high - low)
                      : rc->range - scale * (total - high);
    opus_rc_normalize(rc);
}

static av_always_inline unsigned int opus_rc_getsymbol(OpusRangeCoder *rc, const uint16_t *cdf)
{
    unsigned int k, scale, total, symbol, low, high;

    total = *cdf++;

    scale   = rc->range / total;
    symbol = rc->value / scale + 1;
    symbol = total - FFMIN(symbol, total);

    for (k = 0; cdf[k] <= symbol; k++);
    high = cdf[k];
    low  = k ? cdf[k-1] : 0;

    opus_rc_update(rc, scale, low, high, total);

    return k;
}

static av_always_inline unsigned int opus_rc_p2model(OpusRangeCoder *rc, unsigned int bits)
{
    unsigned int k, scale;
    scale = rc->range >> bits; // in this case, scale = symbol

    if (rc->value >= scale) {
        rc->value -= scale;
        rc->range -= scale;
        k = 0;
    } else {
        rc->range = scale;
        k = 1;
    }
    opus_rc_normalize(rc);
    return k;
}

/**
 * CELT: estimate bits of entropy that have thus far been consumed for the
 *       current CELT frame, to integer and fractional (1/8th bit) precision
 */
static av_always_inline unsigned int opus_rc_tell(const OpusRangeCoder *rc)
{
    return rc->total_read_bits - av_log2(rc->range) - 1;
}

static av_always_inline unsigned int opus_rc_tell_frac(const OpusRangeCoder *rc)
{
    unsigned int i, total_bits, rcbuffer, range;

    total_bits = rc->total_read_bits << 3;
    rcbuffer   = av_log2(rc->range) + 1;
    range      = rc->range >> (rcbuffer-16);

    for (i = 0; i < 3; i++) {
        int bit;
        range = range * range >> 15;
        bit = range >> 16;
        rcbuffer = rcbuffer << 1 | bit;
        range >>= bit;
    }

    return total_bits - rcbuffer;
}

/**
 * CELT: read 1-25 raw bits at the end of the frame, backwards byte-wise
 */
static av_always_inline unsigned int opus_getrawbits(OpusRangeCoder *rc, unsigned int count)
{
    unsigned int value = 0;

    while (rc->rb.bytes && rc->rb.cachelen < count) {
        rc->rb.cacheval |= *--rc->rb.position << rc->rb.cachelen;
        rc->rb.cachelen += 8;
        rc->rb.bytes--;
    }

    value = av_mod_uintp2(rc->rb.cacheval, count);
    rc->rb.cacheval    >>= count;
    rc->rb.cachelen     -= count;
    rc->total_read_bits += count;

    return value;
}

/**
 * CELT: read a uniform distribution
 */
static av_always_inline unsigned int opus_rc_unimodel(OpusRangeCoder *rc, unsigned int size)
{
    unsigned int bits, k, scale, total;

    bits  = opus_ilog(size - 1);
    total = (bits > 8) ? ((size - 1) >> (bits - 8)) + 1 : size;

    scale  = rc->range / total;
    k      = rc->value / scale + 1;
    k      = total - FFMIN(k, total);
    opus_rc_update(rc, scale, k, k + 1, total);

    if (bits > 8) {
        k = k << (bits - 8) | opus_getrawbits(rc, bits - 8);
        return FFMIN(k, size - 1);
    } else
        return k;
}

static av_always_inline int opus_rc_laplace(OpusRangeCoder *rc, unsigned int symbol, int decay)
{
    /* extends the range coder to model a Laplace distribution */
    int value = 0;
    unsigned int scale, low = 0, center;

    scale  = rc->range >> 15;
    center = rc->value / scale + 1;
    center = (1 << 15) - FFMIN(center, 1 << 15);

    if (center >= symbol) {
        value++;
        low = symbol;
        symbol = 1 + ((32768 - 32 - symbol) * (16384-decay) >> 15);

        while (symbol > 1 && center >= low + 2 * symbol) {
            value++;
            symbol *= 2;
            low    += symbol;
            symbol  = (((symbol - 2) * decay) >> 15) + 1;
        }

        if (symbol <= 1) {
            int distance = (center - low) >> 1;
            value += distance;
            low   += 2 * distance;
        }

        if (center < low + symbol)
            value *= -1;
        else
            low += symbol;
    }

    opus_rc_update(rc, scale, low, FFMIN(low + symbol, 32768), 32768);

    return value;
}

static av_always_inline unsigned int opus_rc_stepmodel(OpusRangeCoder *rc, int k0)
{
    /* Use a probability of 3 up to itheta=8192 and then use 1 after */
    unsigned int k, scale, symbol, total = (k0+1)*3 + k0;
    scale  = rc->range / total;
    symbol = rc->value / scale + 1;
    symbol = total - FFMIN(symbol, total);

    k = (symbol < (k0+1)*3) ? symbol/3 : symbol - (k0+1)*2;

    opus_rc_update(rc, scale, (k <= k0) ? 3*(k+0) : (k-1-k0) + 3*(k0+1),
                   (k <= k0) ? 3*(k+1) : (k-0-k0) + 3*(k0+1), total);
    return k;
}

static av_always_inline unsigned int opus_rc_trimodel(OpusRangeCoder *rc, int qn)
{
    unsigned int k, scale, symbol, total, low, center;

    total = ((qn>>1) + 1) * ((qn>>1) + 1);
    scale   = rc->range / total;
    center = rc->value / scale + 1;
    center = total - FFMIN(center, total);

    if (center < total >> 1) {
        k      = (ff_sqrt(8 * center + 1) - 1) >> 1;
        low    = k * (k + 1) >> 1;
        symbol = k + 1;
    } else {
        k      = (2*(qn + 1) - ff_sqrt(8*(total - center - 1) + 1)) >> 1;
        low    = total - ((qn + 1 - k) * (qn + 2 - k) >> 1);
        symbol = qn + 1 - k;
    }

    opus_rc_update(rc, scale, low, low + symbol, total);

    return k;
}

int ff_opus_parse_packet(OpusPacket *pkt, const uint8_t *buf, int buf_size,
                         int self_delimited);

int ff_opus_parse_extradata(AVCodecContext *avctx, OpusContext *s);

int ff_silk_init(AVCodecContext *avctx, SilkContext **ps, int output_channels);
void ff_silk_free(SilkContext **ps);
void ff_silk_flush(SilkContext *s);

/**
 * Decode the LP layer of one Opus frame (which may correspond to several SILK
 * frames).
 */
int ff_silk_decode_superframe(SilkContext *s, OpusRangeCoder *rc,
                              float *output[2],
                              enum OpusBandwidth bandwidth, int coded_channels,
                              int duration_ms);

int ff_celt_init(AVCodecContext *avctx, CeltContext **s, int output_channels);

void ff_celt_free(CeltContext **s);

void ff_celt_flush(CeltContext *s);

int ff_celt_decode_frame(CeltContext *s, OpusRangeCoder *rc,
                         float **output, int coded_channels, int frame_size,
                         int startband,  int endband);

extern const float ff_celt_window2[120];

#endif /* AVCODEC_OPUS_H */