FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/cbs_mpeg2.c
Date: 2025-10-30 00:35:27
Exec Total Coverage
Lines: 90 110 81.8%
Functions: 6 6 100.0%
Branches: 50 78 64.1%
Line Branch Exec Source
1 /*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #include "libavutil/avassert.h"
20
21 #include "cbs.h"
22 #include "cbs_internal.h"
23 #include "cbs_mpeg2.h"
24 #include "startcode.h"
25
26
27 #define HEADER(name) do { \
28 ff_cbs_trace_header(ctx, name); \
29 } while (0)
30
31 #define CHECK(call) do { \
32 err = (call); \
33 if (err < 0) \
34 return err; \
35 } while (0)
36
37 #define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
38 #define FUNC_MPEG2(rw, name) FUNC_NAME(rw, mpeg2, name)
39 #define FUNC(name) FUNC_MPEG2(READWRITE, name)
40
41 #define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
42
43 #define uir(width, name) \
44 xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0, )
45 #define uis(width, name, subs, ...) \
46 xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
47 #define uirs(width, name, subs, ...) \
48 xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
49 #define xui(width, name, var, range_min, range_max, subs, ...) \
50 xuia(width, #name, var, range_min, range_max, subs, __VA_ARGS__)
51 #define sis(width, name, subs, ...) \
52 xsi(width, name, current->name, subs, __VA_ARGS__)
53
54 #define marker_bit() \
55 bit("marker_bit", 1)
56 #define bit(string, value) do { \
57 av_unused uint32_t bit = value; \
58 xuia(1, string, bit, value, value, 0, ); \
59 } while (0)
60
61
62 #define READ
63 #define READWRITE read
64 #define RWContext GetBitContext
65
66 #define ui(width, name) do { \
67 uint32_t value; \
68 CHECK(ff_cbs_read_simple_unsigned(ctx, rw, width, #name, \
69 &value)); \
70 current->name = value; \
71 } while (0)
72 #define xuia(width, string, var, range_min, range_max, subs, ...) do { \
73 uint32_t value; \
74 CHECK(ff_cbs_read_unsigned(ctx, rw, width, string, \
75 SUBSCRIPTS(subs, __VA_ARGS__), \
76 &value, range_min, range_max)); \
77 var = value; \
78 } while (0)
79
80 #define xsi(width, name, var, subs, ...) do { \
81 int32_t value; \
82 CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
83 SUBSCRIPTS(subs, __VA_ARGS__), &value, \
84 MIN_INT_BITS(width), \
85 MAX_INT_BITS(width))); \
86 var = value; \
87 } while (0)
88
89 #define nextbits(width, compare, var) \
90 (get_bits_left(rw) >= width && \
91 (var = show_bits(rw, width)) == (compare))
92
93 #define infer(name, value) do { \
94 current->name = value; \
95 } while (0)
96
97 #include "cbs_mpeg2_syntax_template.c"
98
99 #undef READ
100 #undef READWRITE
101 #undef RWContext
102 #undef ui
103 #undef xuia
104 #undef xsi
105 #undef nextbits
106 #undef infer
107
108
109 #define WRITE
110 #define READWRITE write
111 #define RWContext PutBitContext
112
113 #define ui(width, name) do { \
114 CHECK(ff_cbs_write_simple_unsigned(ctx, rw, width, #name, \
115 current->name)); \
116 } while (0)
117
118 #define xuia(width, string, var, range_min, range_max, subs, ...) do { \
119 CHECK(ff_cbs_write_unsigned(ctx, rw, width, string, \
120 SUBSCRIPTS(subs, __VA_ARGS__), \
121 var, range_min, range_max)); \
122 } while (0)
123
124 #define xsi(width, name, var, subs, ...) do { \
125 CHECK(ff_cbs_write_signed(ctx, rw, width, #name, \
126 SUBSCRIPTS(subs, __VA_ARGS__), var, \
127 MIN_INT_BITS(width), \
128 MAX_INT_BITS(width))); \
129 } while (0)
130
131 #define nextbits(width, compare, var) (var)
132
133 #define infer(name, value) do { \
134 if (current->name != (value)) { \
135 av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
136 "%s does not match inferred value: " \
137 "%"PRId64", but should be %"PRId64".\n", \
138 #name, (int64_t)current->name, (int64_t)(value)); \
139 } \
140 } while (0)
141
142 #include "cbs_mpeg2_syntax_template.c"
143
144 #undef WRITE
145 #undef READWRITE
146 #undef RWContext
147 #undef ui
148 #undef xuia
149 #undef xsi
150 #undef nextbits
151 #undef infer
152
153
154 18 static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
155 CodedBitstreamFragment *frag,
156 int header)
157 {
158 const uint8_t *start;
159 18 uint32_t start_code = -1;
160 int err;
161
162 18 start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
163 &start_code);
164
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 18 if (start_code >> 8 != 0x000001) {
165 // No start code found.
166 ✗ return AVERROR_INVALIDDATA;
167 }
168
169 do {
170 8843 CodedBitstreamUnitType unit_type = start_code & 0xff;
171 const uint8_t *end;
172 size_t unit_size;
173
174 // Reset start_code to ensure that avpriv_find_start_code()
175 // really reads a new start code and does not reuse the old
176 // start code in any way (as e.g. happens when there is a
177 // Sequence End unit at the very end of a packet).
178 8843 start_code = UINT32_MAX;
179 8843 end = avpriv_find_start_code(start--, frag->data + frag->data_size,
180 &start_code);
181
182 // start points to the byte containing the start_code_identifier
183 // (may be the last byte of fragment->data); end points to the byte
184 // following the byte containing the start code identifier (or to
185 // the end of fragment->data).
186
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 8843 if (start_code >> 8 == 0x000001) {
187 // Unit runs from start to the beginning of the start code
188 // pointed to by end (including any padding zeroes).
189 8825 unit_size = (end - 4) - start;
190 } else {
191 // We didn't find a start code, so this is the final unit.
192 18 unit_size = end - start;
193 }
194
195 8843 err = ff_cbs_append_unit_data(frag, unit_type, (uint8_t*)start,
196 unit_size, frag->data_ref);
197
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 8843 if (err < 0)
198 ✗ return err;
199
200 8843 start = end;
201
202 // Do we have a further unit to add to the fragment?
203
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 8843 } while ((start_code >> 8) == 0x000001);
204
205 18 return 0;
206 }
207
208 8843 static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
209 CodedBitstreamUnit *unit)
210 {
211 GetBitContext gbc;
212 int err;
213
214 8843 err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
215
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 8843 if (err < 0)
216 ✗ return err;
217
218 8843 err = ff_cbs_alloc_unit_content(ctx, unit);
219
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 8843 if (err < 0)
220 ✗ return err;
221
222
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 8843 if (MPEG2_START_IS_SLICE(unit->type)) {
223 8746 MPEG2RawSlice *slice = unit->content;
224 int pos, len;
225
226 8746 err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
227
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 8746 if (err < 0)
228 ✗ return err;
229
230
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 8746 if (!get_bits_left(&gbc))
231 ✗ return AVERROR_INVALIDDATA;
232
233 8746 pos = get_bits_count(&gbc);
234 8746 len = unit->data_size;
235
236 8746 slice->data_size = len - pos / 8;
237 8746 slice->data_ref = av_buffer_ref(unit->data_ref);
238
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 8746 if (!slice->data_ref)
239 ✗ return AVERROR(ENOMEM);
240 8746 slice->data = unit->data + pos / 8;
241
242 8746 slice->data_bit_start = pos % 8;
243
244 } else {
245
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 97 switch (unit->type) {
246 #define START(start_code, type, read_func, free_func) \
247 case start_code: \
248 { \
249 type *header = unit->content; \
250 err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
251 if (err < 0) \
252 return err; \
253 } \
254 break;
255
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 19 START(MPEG2_START_PICTURE, MPEG2RawPictureHeader,
256 picture_header, &cbs_mpeg2_free_picture_header);
257
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 14 START(MPEG2_START_USER_DATA, MPEG2RawUserData,
258 user_data, &cbs_mpeg2_free_user_data);
259
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 6 START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader,
260 sequence_header, NULL);
261
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 53 START(MPEG2_START_EXTENSION, MPEG2RawExtensionData,
262 extension_data, NULL);
263
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 2 START(MPEG2_START_GROUP, MPEG2RawGroupOfPicturesHeader,
264 group_of_pictures_header, NULL);
265
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 3 START(MPEG2_START_SEQUENCE_END, MPEG2RawSequenceEnd,
266 sequence_end, NULL);
267 #undef START
268 ✗ default:
269 ✗ return AVERROR(ENOSYS);
270 }
271 }
272
273 8843 return 0;
274 }
275
276 97 static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
277 CodedBitstreamUnit *unit,
278 PutBitContext *pbc)
279 {
280 int err;
281
282
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 97 switch (unit->type) {
283 #define START(start_code, type, func) \
284 case start_code: \
285 err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
286 break;
287 19 START(MPEG2_START_PICTURE, MPEG2RawPictureHeader, picture_header);
288 14 START(MPEG2_START_USER_DATA, MPEG2RawUserData, user_data);
289 6 START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader, sequence_header);
290 53 START(MPEG2_START_EXTENSION, MPEG2RawExtensionData, extension_data);
291 2 START(MPEG2_START_GROUP, MPEG2RawGroupOfPicturesHeader,
292 group_of_pictures_header);
293 3 START(MPEG2_START_SEQUENCE_END, MPEG2RawSequenceEnd, sequence_end);
294 #undef START
295 ✗ default:
296 ✗ av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
297 "code %02"PRIx32".\n", unit->type);
298 ✗ return AVERROR_PATCHWELCOME;
299 }
300
301 97 return err;
302 }
303
304 8746 static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
305 CodedBitstreamUnit *unit,
306 PutBitContext *pbc)
307 {
308 8746 MPEG2RawSlice *slice = unit->content;
309 int err;
310
311 8746 err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
312
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 8746 if (err < 0)
313 ✗ return err;
314
315
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 8746 if (slice->data) {
316 8746 size_t rest = slice->data_size - (slice->data_bit_start + 7) / 8;
317 8746 uint8_t *pos = slice->data + slice->data_bit_start / 8;
318
319
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 8746 av_assert0(slice->data_bit_start >= 0 &&
320 slice->data_size > slice->data_bit_start / 8);
321
322
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 8746 if (slice->data_size * 8 + 8 > put_bits_left(pbc))
323 ✗ return AVERROR(ENOSPC);
324
325 // First copy the remaining bits of the first byte
326
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 8746 if (slice->data_bit_start % 8)
327 8746 put_bits(pbc, 8 - slice->data_bit_start % 8,
328 8746 *pos++ & MAX_UINT_BITS(8 - slice->data_bit_start % 8));
329
330
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 8746 if (put_bits_count(pbc) % 8 == 0) {
331 // If the writer is aligned at this point,
332 // memcpy can be used to improve performance.
333 // This is the normal case.
334 8746 flush_put_bits(pbc);
335 8746 memcpy(put_bits_ptr(pbc), pos, rest);
336 8746 skip_put_bytes(pbc, rest);
337 } else {
338 // If not, we have to copy manually:
339 ✗ for (; rest > 3; rest -= 4, pos += 4)
340 ✗ put_bits32(pbc, AV_RB32(pos));
341
342 ✗ for (; rest; rest--, pos++)
343 ✗ put_bits(pbc, 8, *pos);
344
345 // Align with zeros
346 ✗ put_bits(pbc, 8 - put_bits_count(pbc) % 8, 0);
347 }
348 }
349
350 8746 return 0;
351 }
352
353 8843 static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
354 CodedBitstreamUnit *unit,
355 PutBitContext *pbc)
356 {
357
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 8843 if (MPEG2_START_IS_SLICE(unit->type))
358 8746 return cbs_mpeg2_write_slice (ctx, unit, pbc);
359 else
360 97 return cbs_mpeg2_write_header(ctx, unit, pbc);
361 }
362
363 18 static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
364 CodedBitstreamFragment *frag)
365 {
366 uint8_t *data;
367 size_t size, dp;
368 int i;
369
370 18 size = 0;
371
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 8861 for (i = 0; i < frag->nb_units; i++)
372 8843 size += 3 + frag->units[i].data_size;
373
374 18 frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
375
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 18 if (!frag->data_ref)
376 ✗ return AVERROR(ENOMEM);
377 18 data = frag->data_ref->data;
378
379 18 dp = 0;
380
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 8861 for (i = 0; i < frag->nb_units; i++) {
381 8843 CodedBitstreamUnit *unit = &frag->units[i];
382
383 8843 data[dp++] = 0;
384 8843 data[dp++] = 0;
385 8843 data[dp++] = 1;
386
387 8843 memcpy(data + dp, unit->data, unit->data_size);
388 8843 dp += unit->data_size;
389 }
390
391
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 18 av_assert0(dp == size);
392
393 18 memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
394 18 frag->data = data;
395 18 frag->data_size = size;
396
397 18 return 0;
398 }
399
400 static CodedBitstreamUnitTypeDescriptor cbs_mpeg2_unit_types[] = {
401 CBS_UNIT_TYPE_INTERNAL_REF(MPEG2_START_PICTURE, MPEG2RawPictureHeader,
402 extra_information_picture.extra_information),
403
404 {
405 .nb_unit_types = CBS_UNIT_TYPE_RANGE,
406 .unit_type.range.start = 0x01,
407 .unit_type.range.end = 0xaf,
408
409 .content_type = CBS_CONTENT_TYPE_INTERNAL_REFS,
410 .content_size = sizeof(MPEG2RawSlice),
411 .type.ref = { .nb_offsets = 2,
412 .offsets = { offsetof(MPEG2RawSlice, header.extra_information_slice.extra_information),
413 offsetof(MPEG2RawSlice, data) } },
414 },
415
416 CBS_UNIT_TYPE_INTERNAL_REF(MPEG2_START_USER_DATA, MPEG2RawUserData,
417 user_data),
418
419 CBS_UNIT_TYPE_POD(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader),
420 CBS_UNIT_TYPE_POD(MPEG2_START_EXTENSION, MPEG2RawExtensionData),
421 CBS_UNIT_TYPE_POD(MPEG2_START_SEQUENCE_END, MPEG2RawSequenceEnd),
422 CBS_UNIT_TYPE_POD(MPEG2_START_GROUP, MPEG2RawGroupOfPicturesHeader),
423
424 CBS_UNIT_TYPE_END_OF_LIST
425 };
426
427 const CodedBitstreamType ff_cbs_type_mpeg2 = {
428 .codec_id = AV_CODEC_ID_MPEG2VIDEO,
429
430 .priv_data_size = sizeof(CodedBitstreamMPEG2Context),
431
432 .unit_types = cbs_mpeg2_unit_types,
433
434 .split_fragment = &cbs_mpeg2_split_fragment,
435 .read_unit = &cbs_mpeg2_read_unit,
436 .write_unit = &cbs_mpeg2_write_unit,
437 .assemble_fragment = &cbs_mpeg2_assemble_fragment,
438 };
439