aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/opus_rc.c
blob: 85268bd2842d4130e50e277e73b62ca57cd597d5 (plain) (blame)
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
/*
 * Copyright (c) 2012 Andrew D'Addesio
 * Copyright (c) 2013-2014 Mozilla Corporation
 * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
 *
 * 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
 */

#include "opus_rc.h"

#define OPUS_RC_BITS 32
#define OPUS_RC_SYM  8
#define OPUS_RC_CEIL ((1 << OPUS_RC_SYM) - 1)
#define OPUS_RC_TOP (1u << 31)
#define OPUS_RC_BOT (OPUS_RC_TOP >> OPUS_RC_SYM)
#define OPUS_RC_SHIFT (OPUS_RC_BITS - OPUS_RC_SYM - 1)

static av_always_inline void opus_rc_enc_carryout(OpusRangeCoder *rc, int cbuf)
{
    const int cb = cbuf >> OPUS_RC_SYM, mb = (OPUS_RC_CEIL + cb) & OPUS_RC_CEIL;
    if (cbuf == OPUS_RC_CEIL) {
        rc->ext++;
        return;
    }
    rc->rng_cur[0] = rc->rem + cb;
    rc->rng_cur += (rc->rem >= 0);
    for (; rc->ext > 0; rc->ext--)
        *rc->rng_cur++ = mb;
    av_assert0(rc->rng_cur < rc->rb.position);
    rc->rem = cbuf & OPUS_RC_CEIL; /* Propagate */
}

static av_always_inline void opus_rc_dec_normalize(OpusRangeCoder *rc)
{
    while (rc->range <= OPUS_RC_BOT) {
        rc->value = ((rc->value << OPUS_RC_SYM) | (get_bits(&rc->gb, OPUS_RC_SYM) ^ OPUS_RC_CEIL)) & (OPUS_RC_TOP - 1);
        rc->range     <<= OPUS_RC_SYM;
        rc->total_bits += OPUS_RC_SYM;
    }
}

static av_always_inline void opus_rc_enc_normalize(OpusRangeCoder *rc)
{
    while (rc->range <= OPUS_RC_BOT) {
        opus_rc_enc_carryout(rc, rc->value >> OPUS_RC_SHIFT);
        rc->value = (rc->value << OPUS_RC_SYM) & (OPUS_RC_TOP - 1);
        rc->range     <<= OPUS_RC_SYM;
        rc->total_bits += OPUS_RC_SYM;
    }
}

static av_always_inline void opus_rc_dec_update(OpusRangeCoder *rc, uint32_t scale,
                                                uint32_t low, uint32_t high,
                                                uint32_t total)
{
    rc->value -= scale * (total - high);
    rc->range  = low ? scale * (high - low)
                      : rc->range - scale * (total - high);
    opus_rc_dec_normalize(rc);
}

/* Main encoding function, this needs to go fast */
static av_always_inline void opus_rc_enc_update(OpusRangeCoder *rc, uint32_t b, uint32_t p,
                                                uint32_t p_tot, const int ptwo)
{
    uint32_t rscaled, cnd = !!b;
    if (ptwo) /* Whole function is inlined so hopefully branch is optimized out */
        rscaled = rc->range >> ff_log2(p_tot);
    else
        rscaled = rc->range/p_tot;
    rc->value +=    cnd*(rc->range - rscaled*(p_tot - b));
    rc->range  = (!cnd)*(rc->range - rscaled*(p_tot - p)) + cnd*rscaled*(p - b);
    opus_rc_enc_normalize(rc);
}

uint32_t ff_opus_rc_dec_cdf(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_dec_update(rc, scale, low, high, total);

    return k;
}

void ff_opus_rc_enc_cdf(OpusRangeCoder *rc, int val, const uint16_t *cdf)
{
    opus_rc_enc_update(rc, cdf[val], cdf[val + 1], cdf[0], 1);
}

uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits)
{
    uint32_t 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_dec_normalize(rc);
    return k;
}

void ff_opus_rc_enc_log(OpusRangeCoder *rc, int val, uint32_t bits)
{
    bits = (1 << bits) - 1;
    opus_rc_enc_update(rc, (!!val)*bits, bits + !!val, bits + 1, 1);
}

/**
 * CELT: read 1-25 raw bits at the end of the frame, backwards byte-wise
 */
uint32_t ff_opus_rc_get_raw(OpusRangeCoder *rc, uint32_t count)
{
    uint32_t 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_bits      += count;

    return value;
}

/**
 * CELT: write 0 - 31 bits to the rawbits buffer
 */
void ff_opus_rc_put_raw(OpusRangeCoder *rc, uint32_t val, uint32_t count)
{
    const int to_write = FFMIN(32 - rc->rb.cachelen, count);

    rc->total_bits += count;
    rc->rb.cacheval |= av_mod_uintp2(val, to_write) << rc->rb.cachelen;
    rc->rb.cachelen = (rc->rb.cachelen + to_write) % 32;

    if (!rc->rb.cachelen && count) {
        AV_WB32(rc->rb.position, rc->rb.cacheval);
        rc->rb.bytes    += 4;
        rc->rb.position -= 4;
        rc->rb.cachelen = count - to_write;
        rc->rb.cacheval = av_mod_uintp2(val >> to_write, rc->rb.cachelen);
        av_assert0(rc->rng_cur < rc->rb.position);
    }
}

/**
 * CELT: read a uniform distribution
 */
uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size)
{
    uint32_t 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_dec_update(rc, scale, k, k + 1, total);

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

/**
 * CELT: write a uniformly distributed integer
 */
void ff_opus_rc_enc_uint(OpusRangeCoder *rc, uint32_t val, uint32_t size)
{
    const int ps = FFMAX(opus_ilog(size - 1) - 8, 0);
    opus_rc_enc_update(rc, val >> ps, (val >> ps) + 1, ((size - 1) >> ps) + 1, 0);
    ff_opus_rc_put_raw(rc, val, ps);
}

uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0)
{
    /* Use a probability of 3 up to itheta=8192 and then use 1 after */
    uint32_t 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_dec_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;
}

void ff_opus_rc_enc_uint_step(OpusRangeCoder *rc, uint32_t val, int k0)
{
    const uint32_t a = val <= k0, b = 2*a + 1;
    k0 = (k0 + 1) << 1;
    val = b*(val + k0) - 3*a*k0;
    opus_rc_enc_update(rc, val, val + b, (k0 << 1) - 1, 0);
}

uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn)
{
    uint32_t 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_dec_update(rc, scale, low, low + symbol, total);

    return k;
}

void ff_opus_rc_enc_uint_tri(OpusRangeCoder *rc, uint32_t k, int qn)
{
    uint32_t symbol, low, total;

    total = ((qn>>1) + 1) * ((qn>>1) + 1);

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

    opus_rc_enc_update(rc, low, low + symbol, total, 0);
}

int ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay)
{
    /* extends the range coder to model a Laplace distribution */
    int value = 0;
    uint32_t 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_dec_update(rc, scale, low, FFMIN(low + symbol, 32768), 32768);

    return value;
}

void ff_opus_rc_enc_laplace(OpusRangeCoder *rc, int *value, uint32_t symbol, int decay)
{
    uint32_t low = symbol;
    int i = 1, val = FFABS(*value), pos = *value > 0;
    if (!val) {
        opus_rc_enc_update(rc, 0, symbol, 1 << 15, 1);
        return;
    }
    symbol = ((32768 - 32 - symbol)*(16384 - decay)) >> 15;
    for (; i < val && symbol; i++) {
        low   += (symbol << 1) + 2;
        symbol = (symbol*decay) >> 14;
    }
    if (symbol) {
        low += (++symbol)*pos;
    } else {
        const int distance = FFMIN(val - i, (((32768 - low) - !pos) >> 1) - 1);
        low   += pos + (distance << 1);
        symbol = FFMIN(1, 32768 - low);
        *value = FFSIGN(*value)*(distance + i);
    }
    opus_rc_enc_update(rc, low, low + symbol, 1 << 15, 1);
}

int ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size)
{
    int ret = init_get_bits8(&rc->gb, data, size);
    if (ret < 0)
        return ret;

    rc->range = 128;
    rc->value = 127 - get_bits(&rc->gb, 7);
    rc->total_bits = 9;
    opus_rc_dec_normalize(rc);

    return 0;
}

void ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32_t bytes)
{
    rc->rb.position = rightend;
    rc->rb.bytes    = bytes;
    rc->rb.cachelen = 0;
    rc->rb.cacheval = 0;
}

void ff_opus_rc_enc_end(OpusRangeCoder *rc, uint8_t *dst, int size)
{
    int rng_bytes, bits = OPUS_RC_BITS - opus_ilog(rc->range);
    uint32_t mask = (OPUS_RC_TOP - 1) >> bits;
    uint32_t end = (rc->value + mask) & ~mask;

    if ((end | mask) >= rc->value + rc->range) {
        bits++;
        mask >>= 1;
        end = (rc->value + mask) & ~mask;
    }

    /* Finish what's left */
    while (bits > 0) {
        opus_rc_enc_carryout(rc, end >> OPUS_RC_SHIFT);
        end = (end << OPUS_RC_SYM) & (OPUS_RC_TOP - 1);
        bits -= OPUS_RC_SYM;
    }

    /* Flush out anything left or marked */
    if (rc->rem >= 0 || rc->ext > 0)
        opus_rc_enc_carryout(rc, 0);

    rng_bytes = rc->rng_cur - rc->buf;
    rc->waste = (size - (rc->rb.bytes + rng_bytes)) << 3;
    memcpy(dst, rc->buf, rng_bytes);
    memset(dst + rng_bytes, 0, FFMAX(rc->waste >> 3, 0) + 1);

    /* Put the rawbits part, if any */
    if (rc->rb.bytes || rc->rb.cachelen) {
        int rawbytes = FFALIGN(rc->rb.bytes*8 + rc->rb.cachelen, 8) >> 3;
        int dst_loc = FFMAX(size - rawbytes, 0);
        uint8_t *src = rc->buf + OPUS_MAX_PACKET_SIZE + 12 - rawbytes;
        ff_opus_rc_put_raw(rc, 0, 32 - rc->rb.cachelen);
        dst[dst_loc] |= *src++;
        memcpy(&dst[dst_loc + 1], src, rawbytes - 1);
    }
}

void ff_opus_rc_enc_init(OpusRangeCoder *rc)
{
    rc->value = 0;
    rc->range = OPUS_RC_TOP;
    rc->total_bits = OPUS_RC_BITS + 1;
    rc->rem = -1;
    rc->ext =  0;
    rc->rng_cur = rc->buf;
    ff_opus_rc_dec_raw_init(rc, rc->buf + OPUS_MAX_PACKET_SIZE + 8, 0);
}