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path: root/libavcodec/opus_rc.c (plain)
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1/*
2 * Copyright (c) 2012 Andrew D'Addesio
3 * Copyright (c) 2013-2014 Mozilla Corporation
4 * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
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#include "opus_rc.h"
24
25#define OPUS_RC_BITS 32
26#define OPUS_RC_SYM 8
27#define OPUS_RC_CEIL ((1 << OPUS_RC_SYM) - 1)
28#define OPUS_RC_TOP (1u << 31)
29#define OPUS_RC_BOT (OPUS_RC_TOP >> OPUS_RC_SYM)
30#define OPUS_RC_SHIFT (OPUS_RC_BITS - OPUS_RC_SYM - 1)
31
32static av_always_inline void opus_rc_enc_carryout(OpusRangeCoder *rc, int cbuf)
33{
34 const int cb = cbuf >> OPUS_RC_SYM, mb = (OPUS_RC_CEIL + cb) & OPUS_RC_CEIL;
35 if (cbuf == OPUS_RC_CEIL) {
36 rc->ext++;
37 return;
38 }
39 rc->rng_cur[0] = rc->rem + cb;
40 rc->rng_cur += (rc->rem >= 0);
41 for (; rc->ext > 0; rc->ext--)
42 *rc->rng_cur++ = mb;
43 av_assert0(rc->rng_cur < rc->rb.position);
44 rc->rem = cbuf & OPUS_RC_CEIL; /* Propagate */
45}
46
47static av_always_inline void opus_rc_dec_normalize(OpusRangeCoder *rc)
48{
49 while (rc->range <= OPUS_RC_BOT) {
50 rc->value = ((rc->value << OPUS_RC_SYM) | (get_bits(&rc->gb, OPUS_RC_SYM) ^ OPUS_RC_CEIL)) & (OPUS_RC_TOP - 1);
51 rc->range <<= OPUS_RC_SYM;
52 rc->total_bits += OPUS_RC_SYM;
53 }
54}
55
56static av_always_inline void opus_rc_enc_normalize(OpusRangeCoder *rc)
57{
58 while (rc->range <= OPUS_RC_BOT) {
59 opus_rc_enc_carryout(rc, rc->value >> OPUS_RC_SHIFT);
60 rc->value = (rc->value << OPUS_RC_SYM) & (OPUS_RC_TOP - 1);
61 rc->range <<= OPUS_RC_SYM;
62 rc->total_bits += OPUS_RC_SYM;
63 }
64}
65
66static av_always_inline void opus_rc_dec_update(OpusRangeCoder *rc, uint32_t scale,
67 uint32_t low, uint32_t high,
68 uint32_t total)
69{
70 rc->value -= scale * (total - high);
71 rc->range = low ? scale * (high - low)
72 : rc->range - scale * (total - high);
73 opus_rc_dec_normalize(rc);
74}
75
76/* Main encoding function, this needs to go fast */
77static av_always_inline void opus_rc_enc_update(OpusRangeCoder *rc, uint32_t b, uint32_t p,
78 uint32_t p_tot, const int ptwo)
79{
80 uint32_t rscaled, cnd = !!b;
81 if (ptwo) /* Whole function is inlined so hopefully branch is optimized out */
82 rscaled = rc->range >> ff_log2(p_tot);
83 else
84 rscaled = rc->range/p_tot;
85 rc->value += cnd*(rc->range - rscaled*(p_tot - b));
86 rc->range = (!cnd)*(rc->range - rscaled*(p_tot - p)) + cnd*rscaled*(p - b);
87 opus_rc_enc_normalize(rc);
88}
89
90uint32_t ff_opus_rc_dec_cdf(OpusRangeCoder *rc, const uint16_t *cdf)
91{
92 unsigned int k, scale, total, symbol, low, high;
93
94 total = *cdf++;
95
96 scale = rc->range / total;
97 symbol = rc->value / scale + 1;
98 symbol = total - FFMIN(symbol, total);
99
100 for (k = 0; cdf[k] <= symbol; k++);
101 high = cdf[k];
102 low = k ? cdf[k-1] : 0;
103
104 opus_rc_dec_update(rc, scale, low, high, total);
105
106 return k;
107}
108
109void ff_opus_rc_enc_cdf(OpusRangeCoder *rc, int val, const uint16_t *cdf)
110{
111 opus_rc_enc_update(rc, cdf[val], cdf[val + 1], cdf[0], 1);
112}
113
114uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits)
115{
116 uint32_t k, scale;
117 scale = rc->range >> bits; // in this case, scale = symbol
118
119 if (rc->value >= scale) {
120 rc->value -= scale;
121 rc->range -= scale;
122 k = 0;
123 } else {
124 rc->range = scale;
125 k = 1;
126 }
127 opus_rc_dec_normalize(rc);
128 return k;
129}
130
131void ff_opus_rc_enc_log(OpusRangeCoder *rc, int val, uint32_t bits)
132{
133 bits = (1 << bits) - 1;
134 opus_rc_enc_update(rc, (!!val)*bits, bits + !!val, bits + 1, 1);
135}
136
137/**
138 * CELT: read 1-25 raw bits at the end of the frame, backwards byte-wise
139 */
140uint32_t ff_opus_rc_get_raw(OpusRangeCoder *rc, uint32_t count)
141{
142 uint32_t value = 0;
143
144 while (rc->rb.bytes && rc->rb.cachelen < count) {
145 rc->rb.cacheval |= *--rc->rb.position << rc->rb.cachelen;
146 rc->rb.cachelen += 8;
147 rc->rb.bytes--;
148 }
149
150 value = av_mod_uintp2(rc->rb.cacheval, count);
151 rc->rb.cacheval >>= count;
152 rc->rb.cachelen -= count;
153 rc->total_bits += count;
154
155 return value;
156}
157
158/**
159 * CELT: write 0 - 31 bits to the rawbits buffer
160 */
161void ff_opus_rc_put_raw(OpusRangeCoder *rc, uint32_t val, uint32_t count)
162{
163 const int to_write = FFMIN(32 - rc->rb.cachelen, count);
164
165 rc->total_bits += count;
166 rc->rb.cacheval |= av_mod_uintp2(val, to_write) << rc->rb.cachelen;
167 rc->rb.cachelen = (rc->rb.cachelen + to_write) % 32;
168
169 if (!rc->rb.cachelen && count) {
170 AV_WB32(rc->rb.position, rc->rb.cacheval);
171 rc->rb.bytes += 4;
172 rc->rb.position -= 4;
173 rc->rb.cachelen = count - to_write;
174 rc->rb.cacheval = av_mod_uintp2(val >> to_write, rc->rb.cachelen);
175 av_assert0(rc->rng_cur < rc->rb.position);
176 }
177}
178
179/**
180 * CELT: read a uniform distribution
181 */
182uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size)
183{
184 uint32_t bits, k, scale, total;
185
186 bits = opus_ilog(size - 1);
187 total = (bits > 8) ? ((size - 1) >> (bits - 8)) + 1 : size;
188
189 scale = rc->range / total;
190 k = rc->value / scale + 1;
191 k = total - FFMIN(k, total);
192 opus_rc_dec_update(rc, scale, k, k + 1, total);
193
194 if (bits > 8) {
195 k = k << (bits - 8) | ff_opus_rc_get_raw(rc, bits - 8);
196 return FFMIN(k, size - 1);
197 } else
198 return k;
199}
200
201/**
202 * CELT: write a uniformly distributed integer
203 */
204void ff_opus_rc_enc_uint(OpusRangeCoder *rc, uint32_t val, uint32_t size)
205{
206 const int ps = FFMAX(opus_ilog(size - 1) - 8, 0);
207 opus_rc_enc_update(rc, val >> ps, (val >> ps) + 1, ((size - 1) >> ps) + 1, 0);
208 ff_opus_rc_put_raw(rc, val, ps);
209}
210
211uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0)
212{
213 /* Use a probability of 3 up to itheta=8192 and then use 1 after */
214 uint32_t k, scale, symbol, total = (k0+1)*3 + k0;
215 scale = rc->range / total;
216 symbol = rc->value / scale + 1;
217 symbol = total - FFMIN(symbol, total);
218
219 k = (symbol < (k0+1)*3) ? symbol/3 : symbol - (k0+1)*2;
220
221 opus_rc_dec_update(rc, scale, (k <= k0) ? 3*(k+0) : (k-1-k0) + 3*(k0+1),
222 (k <= k0) ? 3*(k+1) : (k-0-k0) + 3*(k0+1), total);
223 return k;
224}
225
226void ff_opus_rc_enc_uint_step(OpusRangeCoder *rc, uint32_t val, int k0)
227{
228 const uint32_t a = val <= k0, b = 2*a + 1;
229 k0 = (k0 + 1) << 1;
230 val = b*(val + k0) - 3*a*k0;
231 opus_rc_enc_update(rc, val, val + b, (k0 << 1) - 1, 0);
232}
233
234uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn)
235{
236 uint32_t k, scale, symbol, total, low, center;
237
238 total = ((qn>>1) + 1) * ((qn>>1) + 1);
239 scale = rc->range / total;
240 center = rc->value / scale + 1;
241 center = total - FFMIN(center, total);
242
243 if (center < total >> 1) {
244 k = (ff_sqrt(8 * center + 1) - 1) >> 1;
245 low = k * (k + 1) >> 1;
246 symbol = k + 1;
247 } else {
248 k = (2*(qn + 1) - ff_sqrt(8*(total - center - 1) + 1)) >> 1;
249 low = total - ((qn + 1 - k) * (qn + 2 - k) >> 1);
250 symbol = qn + 1 - k;
251 }
252
253 opus_rc_dec_update(rc, scale, low, low + symbol, total);
254
255 return k;
256}
257
258void ff_opus_rc_enc_uint_tri(OpusRangeCoder *rc, uint32_t k, int qn)
259{
260 uint32_t symbol, low, total;
261
262 total = ((qn>>1) + 1) * ((qn>>1) + 1);
263
264 if (k <= qn >> 1) {
265 low = k * (k + 1) >> 1;
266 symbol = k + 1;
267 } else {
268 low = total - ((qn + 1 - k) * (qn + 2 - k) >> 1);
269 symbol = qn + 1 - k;
270 }
271
272 opus_rc_enc_update(rc, low, low + symbol, total, 0);
273}
274
275int ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay)
276{
277 /* extends the range coder to model a Laplace distribution */
278 int value = 0;
279 uint32_t scale, low = 0, center;
280
281 scale = rc->range >> 15;
282 center = rc->value / scale + 1;
283 center = (1 << 15) - FFMIN(center, 1 << 15);
284
285 if (center >= symbol) {
286 value++;
287 low = symbol;
288 symbol = 1 + ((32768 - 32 - symbol) * (16384-decay) >> 15);
289
290 while (symbol > 1 && center >= low + 2 * symbol) {
291 value++;
292 symbol *= 2;
293 low += symbol;
294 symbol = (((symbol - 2) * decay) >> 15) + 1;
295 }
296
297 if (symbol <= 1) {
298 int distance = (center - low) >> 1;
299 value += distance;
300 low += 2 * distance;
301 }
302
303 if (center < low + symbol)
304 value *= -1;
305 else
306 low += symbol;
307 }
308
309 opus_rc_dec_update(rc, scale, low, FFMIN(low + symbol, 32768), 32768);
310
311 return value;
312}
313
314void ff_opus_rc_enc_laplace(OpusRangeCoder *rc, int *value, uint32_t symbol, int decay)
315{
316 uint32_t low = symbol;
317 int i = 1, val = FFABS(*value), pos = *value > 0;
318 if (!val) {
319 opus_rc_enc_update(rc, 0, symbol, 1 << 15, 1);
320 return;
321 }
322 symbol = ((32768 - 32 - symbol)*(16384 - decay)) >> 15;
323 for (; i < val && symbol; i++) {
324 low += (symbol << 1) + 2;
325 symbol = (symbol*decay) >> 14;
326 }
327 if (symbol) {
328 low += (++symbol)*pos;
329 } else {
330 const int distance = FFMIN(val - i, (((32768 - low) - !pos) >> 1) - 1);
331 low += pos + (distance << 1);
332 symbol = FFMIN(1, 32768 - low);
333 *value = FFSIGN(*value)*(distance + i);
334 }
335 opus_rc_enc_update(rc, low, low + symbol, 1 << 15, 1);
336}
337
338int ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size)
339{
340 int ret = init_get_bits8(&rc->gb, data, size);
341 if (ret < 0)
342 return ret;
343
344 rc->range = 128;
345 rc->value = 127 - get_bits(&rc->gb, 7);
346 rc->total_bits = 9;
347 opus_rc_dec_normalize(rc);
348
349 return 0;
350}
351
352void ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32_t bytes)
353{
354 rc->rb.position = rightend;
355 rc->rb.bytes = bytes;
356 rc->rb.cachelen = 0;
357 rc->rb.cacheval = 0;
358}
359
360void ff_opus_rc_enc_end(OpusRangeCoder *rc, uint8_t *dst, int size)
361{
362 int rng_bytes, bits = OPUS_RC_BITS - opus_ilog(rc->range);
363 uint32_t mask = (OPUS_RC_TOP - 1) >> bits;
364 uint32_t end = (rc->value + mask) & ~mask;
365
366 if ((end | mask) >= rc->value + rc->range) {
367 bits++;
368 mask >>= 1;
369 end = (rc->value + mask) & ~mask;
370 }
371
372 /* Finish what's left */
373 while (bits > 0) {
374 opus_rc_enc_carryout(rc, end >> OPUS_RC_SHIFT);
375 end = (end << OPUS_RC_SYM) & (OPUS_RC_TOP - 1);
376 bits -= OPUS_RC_SYM;
377 }
378
379 /* Flush out anything left or marked */
380 if (rc->rem >= 0 || rc->ext > 0)
381 opus_rc_enc_carryout(rc, 0);
382
383 rng_bytes = rc->rng_cur - rc->buf;
384 rc->waste = (size - (rc->rb.bytes + rng_bytes)) << 3;
385 memcpy(dst, rc->buf, rng_bytes);
386 memset(dst + rng_bytes, 0, FFMAX(rc->waste >> 3, 0) + 1);
387
388 /* Put the rawbits part, if any */
389 if (rc->rb.bytes || rc->rb.cachelen) {
390 int rawbytes = FFALIGN(rc->rb.bytes*8 + rc->rb.cachelen, 8) >> 3;
391 int dst_loc = FFMAX(size - rawbytes, 0);
392 uint8_t *src = rc->buf + OPUS_MAX_PACKET_SIZE + 12 - rawbytes;
393 ff_opus_rc_put_raw(rc, 0, 32 - rc->rb.cachelen);
394 dst[dst_loc] |= *src++;
395 memcpy(&dst[dst_loc + 1], src, rawbytes - 1);
396 }
397}
398
399void ff_opus_rc_enc_init(OpusRangeCoder *rc)
400{
401 rc->value = 0;
402 rc->range = OPUS_RC_TOP;
403 rc->total_bits = OPUS_RC_BITS + 1;
404 rc->rem = -1;
405 rc->ext = 0;
406 rc->rng_cur = rc->buf;
407 ff_opus_rc_dec_raw_init(rc, rc->buf + OPUS_MAX_PACKET_SIZE + 8, 0);
408}
409
generated by cgit at 2024-05-17 05:05:39 (GMT)