FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/dstdec.c
Date: 2025-11-10 16:28:23
Exec Total Coverage
Lines: 123 176 69.9%
Functions: 9 10 90.0%
Branches: 54 100 54.0%
Line Branch Exec Source
1 /*
2 * Direct Stream Transfer (DST) decoder
3 * Copyright (c) 2014 Peter Ross <pross@xvid.org>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * Direct Stream Transfer (DST) decoder
25 * ISO/IEC 14496-3 Part 3 Subpart 10: Technical description of lossless coding of oversampled audio
26 */
27
28 #include "libavutil/intreadwrite.h"
29 #include "libavutil/mem_internal.h"
30 #include "libavutil/reverse.h"
31 #include "codec_internal.h"
32 #include "decode.h"
33 #include "get_bits.h"
34 #include "avcodec.h"
35 #include "golomb.h"
36 #include "dsd.h"
37
38 #define DST_MAX_CHANNELS 6
39 #define DST_MAX_ELEMENTS (2 * DST_MAX_CHANNELS)
40
41 #define DSD_FS44(sample_rate) (sample_rate * 8LL / 44100)
42
43 #define DST_SAMPLES_PER_FRAME(sample_rate) (588 * DSD_FS44(sample_rate))
44
45 static const int8_t fsets_code_pred_coeff[3][3] = {
46 { -8 },
47 { -16, 8 },
48 { -9, -5, 6 },
49 };
50
51 static const int8_t probs_code_pred_coeff[3][3] = {
52 { -8 },
53 { -16, 8 },
54 { -24, 24, -8 },
55 };
56
57 typedef struct ArithCoder {
58 unsigned int a;
59 unsigned int c;
60 } ArithCoder;
61
62 typedef struct Table {
63 unsigned int elements;
64 unsigned int length[DST_MAX_ELEMENTS];
65 int coeff[DST_MAX_ELEMENTS][128];
66 } Table;
67
68 typedef struct DSTContext {
69 AVClass *class;
70
71 GetBitContext gb;
72 ArithCoder ac;
73 Table fsets, probs;
74 DECLARE_ALIGNED(16, uint8_t, status)[DST_MAX_CHANNELS][16];
75 DECLARE_ALIGNED(16, int16_t, filter)[DST_MAX_ELEMENTS][16][256];
76 DSDContext dsdctx[DST_MAX_CHANNELS];
77 } DSTContext;
78
79 2 static av_cold int decode_init(AVCodecContext *avctx)
80 {
81 2 DSTContext *s = avctx->priv_data;
82 int i;
83
84
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 2 if (avctx->ch_layout.nb_channels > DST_MAX_CHANNELS) {
85 ✗ avpriv_request_sample(avctx, "Channel count %d", avctx->ch_layout.nb_channels);
86 ✗ return AVERROR_PATCHWELCOME;
87 }
88
89 // the sample rate is only allowed to be 64,128,256 * 44100 by ISO/IEC 14496-3:2005(E)
90 // We are a bit more tolerant here, but this check is needed to bound the size and duration
91
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 2 if (avctx->sample_rate > 512 * 44100)
92 ✗ return AVERROR_INVALIDDATA;
93
94
95
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 2 if (DST_SAMPLES_PER_FRAME(avctx->sample_rate) & 7) {
96 ✗ return AVERROR_PATCHWELCOME;
97 }
98
99 2 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
100
101
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 6 for (i = 0; i < avctx->ch_layout.nb_channels; i++)
102 4 memset(s->dsdctx[i].buf, 0x69, sizeof(s->dsdctx[i].buf));
103
104 2 ff_init_dsd_data();
105
106 2 return 0;
107 }
108
109 10 static int read_map(GetBitContext *gb, Table *t, unsigned int map[DST_MAX_CHANNELS], int channels)
110 {
111 int ch;
112 10 t->elements = 1;
113 10 map[0] = 0;
114
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 10 if (!get_bits1(gb)) {
115
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 20 for (ch = 1; ch < channels; ch++) {
116 10 int bits = av_log2(t->elements) + 1;
117 10 map[ch] = get_bits(gb, bits);
118
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 10 if (map[ch] == t->elements) {
119 10 t->elements++;
120
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 10 if (t->elements >= DST_MAX_ELEMENTS)
121 ✗ return AVERROR_INVALIDDATA;
122 ✗ } else if (map[ch] > t->elements) {
123 ✗ return AVERROR_INVALIDDATA;
124 }
125 }
126 } else {
127 ✗ memset(map, 0, sizeof(*map) * DST_MAX_CHANNELS);
128 }
129 10 return 0;
130 }
131
132 ✗ static av_always_inline int get_sr_golomb_dst(GetBitContext *gb, unsigned int k)
133 {
134 ✗ int v = get_ur_golomb_jpegls(gb, k, get_bits_left(gb), 0);
135 ✗ if (v && get_bits1(gb))
136 ✗ v = -v;
137 ✗ return v;
138 }
139
140 40 static void read_uncoded_coeff(GetBitContext *gb, int *dst, unsigned int elements,
141 int coeff_bits, int is_signed, int offset)
142 {
143 int i;
144
145
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 3880 for (i = 0; i < elements; i++) {
146
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 3840 dst[i] = (is_signed ? get_sbits(gb, coeff_bits) : get_bits(gb, coeff_bits)) + offset;
147 }
148 40 }
149
150 20 static int read_table(GetBitContext *gb, Table *t, const int8_t code_pred_coeff[3][3],
151 int length_bits, int coeff_bits, int is_signed, int offset)
152 {
153 unsigned int i, j, k;
154
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 60 for (i = 0; i < t->elements; i++) {
155 40 t->length[i] = get_bits(gb, length_bits) + 1;
156
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 40 if (!get_bits1(gb)) {
157 40 read_uncoded_coeff(gb, t->coeff[i], t->length[i], coeff_bits, is_signed, offset);
158 } else {
159 ✗ int method = get_bits(gb, 2), lsb_size;
160 ✗ if (method == 3)
161 ✗ return AVERROR_INVALIDDATA;
162
163 ✗ read_uncoded_coeff(gb, t->coeff[i], method + 1, coeff_bits, is_signed, offset);
164
165 ✗ lsb_size = get_bits(gb, 3);
166 ✗ for (j = method + 1; j < t->length[i]; j++) {
167 ✗ int c, x = 0;
168 ✗ for (k = 0; k < method + 1; k++)
169 ✗ x += code_pred_coeff[method][k] * (unsigned)t->coeff[i][j - k - 1];
170 ✗ c = get_sr_golomb_dst(gb, lsb_size);
171 ✗ if (x >= 0)
172 ✗ c -= (x + 4) / 8;
173 else
174 ✗ c += (-x + 3) / 8;
175 ✗ if (!is_signed) {
176 ✗ if (c < offset || c >= offset + (1<<coeff_bits))
177 ✗ return AVERROR_INVALIDDATA;
178 }
179 ✗ t->coeff[i][j] = c;
180 }
181 }
182 }
183 20 return 0;
184 }
185
186 10 static void ac_init(ArithCoder *ac, GetBitContext *gb)
187 {
188 10 ac->a = 4095;
189 10 ac->c = get_bits(gb, 12);
190 10 }
191
192 752650 static av_always_inline void ac_get(ArithCoder *ac, GetBitContext *gb, int p, int *e)
193 {
194 752650 unsigned int k = (ac->a >> 8) | ((ac->a >> 7) & 1);
195 752650 unsigned int q = k * p;
196 752650 unsigned int a_q = ac->a - q;
197
198 752650 *e = ac->c < a_q;
199
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 752650 if (*e) {
200 637782 ac->a = a_q;
201 } else {
202 114868 ac->a = q;
203 114868 ac->c -= a_q;
204 }
205
206
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 752650 if (ac->a < 2048) {
207 247803 int n = 11 - av_log2(ac->a);
208 247803 ac->a <<= n;
209 247803 ac->c = (ac->c << n) | get_bits(gb, n);
210 }
211 752650 }
212
213 10 static uint8_t prob_dst_x_bit(int c)
214 {
215 10 return (ff_reverse[c & 127] >> 1) + 1;
216 }
217
218 10 static int build_filter(int16_t table[DST_MAX_ELEMENTS][16][256], const Table *fsets)
219 {
220 int i, j, k, l;
221
222
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 30 for (i = 0; i < fsets->elements; i++) {
223 20 int length = fsets->length[i];
224
225
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 340 for (j = 0; j < 16; j++) {
226 320 int total = av_clip(length - j * 8, 0, 8);
227
228
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 82240 for (k = 0; k < 256; k++) {
229 81920 int64_t v = 0;
230
231
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 737280 for (l = 0; l < total; l++)
232 655360 v += (((k >> l) & 1) * 2 - 1) * fsets->coeff[i][j * 8 + l];
233
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 81920 if ((int16_t)v != v)
234 ✗ return AVERROR_INVALIDDATA;
235 81920 table[i][j][k] = v;
236 }
237 }
238 }
239 10 return 0;
240 }
241
242 10 static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
243 int *got_frame_ptr, AVPacket *avpkt)
244 {
245 10 unsigned samples_per_frame = DST_SAMPLES_PER_FRAME(avctx->sample_rate);
246 unsigned map_ch_to_felem[DST_MAX_CHANNELS];
247 unsigned map_ch_to_pelem[DST_MAX_CHANNELS];
248 unsigned i, ch, same_map, dst_x_bit;
249 unsigned half_prob[DST_MAX_CHANNELS];
250 10 const int channels = avctx->ch_layout.nb_channels;
251 10 DSTContext *s = avctx->priv_data;
252 10 GetBitContext *gb = &s->gb;
253 10 ArithCoder *ac = &s->ac;
254 uint8_t *dsd;
255 float *pcm;
256 int ret;
257
258
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 10 if (avpkt->size <= 1)
259 ✗ return AVERROR_INVALIDDATA;
260
261 10 frame->nb_samples = samples_per_frame / 8;
262
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 10 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
263 ✗ return ret;
264 10 dsd = frame->data[0];
265 10 pcm = (float *)frame->data[0];
266
267
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 10 if ((ret = init_get_bits8(gb, avpkt->data, avpkt->size)) < 0)
268 ✗ return ret;
269
270
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 10 if (!get_bits1(gb)) {
271 ✗ skip_bits1(gb);
272 ✗ if (get_bits(gb, 6))
273 ✗ return AVERROR_INVALIDDATA;
274 ✗ memcpy(frame->data[0], avpkt->data + 1, FFMIN(avpkt->size - 1, frame->nb_samples * channels));
275 ✗ goto dsd;
276 }
277
278 /* Segmentation (10.4, 10.5, 10.6) */
279
280
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 10 if (!get_bits1(gb)) {
281 ✗ avpriv_request_sample(avctx, "Not Same Segmentation");
282 ✗ return AVERROR_PATCHWELCOME;
283 }
284
285
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 10 if (!get_bits1(gb)) {
286 ✗ avpriv_request_sample(avctx, "Not Same Segmentation For All Channels");
287 ✗ return AVERROR_PATCHWELCOME;
288 }
289
290
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 10 if (!get_bits1(gb)) {
291 ✗ avpriv_request_sample(avctx, "Not End Of Channel Segmentation");
292 ✗ return AVERROR_PATCHWELCOME;
293 }
294
295 /* Mapping (10.7, 10.8, 10.9) */
296
297 10 same_map = get_bits1(gb);
298
299
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 10 if ((ret = read_map(gb, &s->fsets, map_ch_to_felem, channels)) < 0)
300 ✗ return ret;
301
302
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 10 if (same_map) {
303 10 s->probs.elements = s->fsets.elements;
304 10 memcpy(map_ch_to_pelem, map_ch_to_felem, sizeof(map_ch_to_felem));
305 } else {
306 ✗ avpriv_request_sample(avctx, "Not Same Mapping");
307 ✗ if ((ret = read_map(gb, &s->probs, map_ch_to_pelem, channels)) < 0)
308 ✗ return ret;
309 }
310
311 /* Half Probability (10.10) */
312
313
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 30 for (ch = 0; ch < channels; ch++)
314 20 half_prob[ch] = get_bits1(gb);
315
316 /* Filter Coef Sets (10.12) */
317
318 10 ret = read_table(gb, &s->fsets, fsets_code_pred_coeff, 7, 9, 1, 0);
319
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 10 if (ret < 0)
320 ✗ return ret;
321
322 /* Probability Tables (10.13) */
323
324 10 ret = read_table(gb, &s->probs, probs_code_pred_coeff, 6, 7, 0, 1);
325
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 10 if (ret < 0)
326 ✗ return ret;
327
328 /* Arithmetic Coded Data (10.11) */
329
330
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 10 if (get_bits1(gb))
331 ✗ return AVERROR_INVALIDDATA;
332 10 ac_init(ac, gb);
333
334 10 ret = build_filter(s->filter, &s->fsets);
335
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 10 if (ret < 0)
336 ✗ return ret;
337
338 10 memset(s->status, 0xAA, sizeof(s->status));
339 10 memset(dsd, 0, frame->nb_samples * 4 * channels);
340
341 10 ac_get(ac, gb, prob_dst_x_bit(s->fsets.coeff[0][0]), &dst_x_bit);
342
343
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 376330 for (i = 0; i < samples_per_frame; i++) {
344
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 1128960 for (ch = 0; ch < channels; ch++) {
345 752640 const unsigned felem = map_ch_to_felem[ch];
346 752640 int16_t (*filter)[256] = s->filter[felem];
347 752640 uint8_t *status = s->status[ch];
348 int prob, residual, v;
349
350 #define F(x) filter[(x)][status[(x)]]
351 752640 const int16_t predict = F( 0) + F( 1) + F( 2) + F( 3) +
352 752640 F( 4) + F( 5) + F( 6) + F( 7) +
353 752640 F( 8) + F( 9) + F(10) + F(11) +
354 752640 F(12) + F(13) + F(14) + F(15);
355 #undef F
356
357
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 752640 if (!half_prob[ch] || i >= s->fsets.length[felem]) {
358 750080 unsigned pelem = map_ch_to_pelem[ch];
359 750080 unsigned index = FFABS(predict) >> 3;
360 750080 prob = s->probs.coeff[pelem][FFMIN(index, s->probs.length[pelem] - 1)];
361 } else {
362 2560 prob = 128;
363 }
364
365 752640 ac_get(ac, gb, prob, &residual);
366 752640 v = ((predict >> 15) ^ residual) & 1;
367 752640 dsd[((i >> 3) * channels + ch) << 2] |= v << (7 - (i & 0x7 ));
368
369 752640 AV_WL64A(status + 8, (AV_RL64A(status + 8) << 1) | ((AV_RL64A(status) >> 63) & 1));
370 752640 AV_WL64A(status, (AV_RL64A(status) << 1) | v);
371 }
372 }
373
374 10 dsd:
375
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 30 for (i = 0; i < channels; i++) {
376 20 ff_dsd2pcm_translate(&s->dsdctx[i], frame->nb_samples, 0,
377 20 frame->data[0] + i * 4,
378 20 channels * 4, pcm + i, channels);
379 }
380
381 10 *got_frame_ptr = 1;
382
383 10 return avpkt->size;
384 }
385
386 const FFCodec ff_dst_decoder = {
387 .p.name = "dst",
388 CODEC_LONG_NAME("DST (Digital Stream Transfer)"),
389 .p.type = AVMEDIA_TYPE_AUDIO,
390 .p.id = AV_CODEC_ID_DST,
391 .priv_data_size = sizeof(DSTContext),
392 .init = decode_init,
393 FF_CODEC_DECODE_CB(decode_frame),
394 .p.capabilities = AV_CODEC_CAP_DR1,
395 CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_FLT),
396 };
397