2 * This file is part of FFmpeg.
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.
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.
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
19 #include "libavutil/avassert.h"
22 #include "cbs_internal.h"
23 #include "cbs_mpeg2.h"
27 #define HEADER(name) do { \
28 ff_cbs_trace_header(ctx, name); \
31 #define CHECK(call) do { \
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)
43 #define READWRITE read
44 #define RWContext GetBitContext
46 #define xui(width, name, var) do { \
48 CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
49 &value, 0, (1 << width) - 1)); \
53 #define ui(width, name) \
54 xui(width, name, current->name)
56 #define marker_bit() do { \
57 av_unused uint32_t one; \
58 CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", &one, 1, 1)); \
61 #define nextbits(width, compare, var) \
62 (get_bits_left(rw) >= width && \
63 (var = show_bits(rw, width)) == (compare))
65 #include "cbs_mpeg2_syntax_template.c"
77 #define READWRITE write
78 #define RWContext PutBitContext
80 #define xui(width, name, var) do { \
81 CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
82 var, 0, (1 << width) - 1)); \
85 #define ui(width, name) \
86 xui(width, name, current->name)
88 #define marker_bit() do { \
89 CHECK(ff_cbs_write_unsigned(ctx, rw, 1, "marker_bit", 1, 1, 1)); \
92 #define nextbits(width, compare, var) (var)
94 #include "cbs_mpeg2_syntax_template.c"
105 static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
106 CodedBitstreamFragment *frag,
109 const uint8_t *start, *end;
111 uint32_t start_code = -1, next_start_code = -1;
113 int err, i, unit_type;
115 start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
118 end = avpriv_find_start_code(start, frag->data + frag->data_size,
121 unit_type = start_code & 0xff;
123 // The start and end pointers point at to the byte following the
124 // start_code_identifier in the start code that they found.
125 if (end == frag->data + frag->data_size) {
126 // We didn't find a start code, so this is the final unit.
127 unit_size = end - (start - 1);
129 // Unit runs from start to the beginning of the start code
130 // pointed to by end (including any padding zeroes).
131 unit_size = (end - 4) - (start - 1);
134 unit_data = av_malloc(unit_size + AV_INPUT_BUFFER_PADDING_SIZE);
136 return AVERROR(ENOMEM);
137 memcpy(unit_data, start - 1, unit_size);
138 memset(unit_data + unit_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
140 err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
141 unit_data, unit_size);
143 av_freep(&unit_data);
147 if (end == frag->data + frag->data_size)
150 start_code = next_start_code;
157 static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
158 CodedBitstreamUnit *unit)
163 err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
167 if (MPEG2_START_IS_SLICE(unit->type)) {
168 MPEG2RawSlice *slice;
171 slice = av_mallocz(sizeof(*slice));
173 return AVERROR(ENOMEM);
174 err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
180 pos = get_bits_count(&gbc);
181 len = unit->data_size;
183 slice->data_size = len - pos / 8;
184 slice->data = av_malloc(slice->data_size +
185 AV_INPUT_BUFFER_PADDING_SIZE);
188 return AVERROR(ENOMEM);
192 unit->data + pos / 8, slice->data_size);
193 memset(slice->data + slice->data_size, 0,
194 AV_INPUT_BUFFER_PADDING_SIZE);
195 slice->data_bit_start = pos % 8;
197 unit->content = slice;
200 switch (unit->type) {
201 #define START(start_code, type, func) \
205 header = av_mallocz(sizeof(*header)); \
207 return AVERROR(ENOMEM); \
208 err = cbs_mpeg2_read_ ## func(ctx, &gbc, header); \
213 unit->content = header; \
216 START(0x00, MPEG2RawPictureHeader, picture_header);
217 START(0xb2, MPEG2RawUserData, user_data);
218 START(0xb3, MPEG2RawSequenceHeader, sequence_header);
219 START(0xb5, MPEG2RawExtensionData, extension_data);
220 START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
223 av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %"PRIx32".\n",
225 return AVERROR_INVALIDDATA;
232 static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
233 CodedBitstreamUnit *unit,
238 switch (unit->type) {
239 #define START(start_code, type, func) \
241 err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
243 START(0x00, MPEG2RawPictureHeader, picture_header);
244 START(0xb2, MPEG2RawUserData, user_data);
245 START(0xb3, MPEG2RawSequenceHeader, sequence_header);
246 START(0xb5, MPEG2RawExtensionData, extension_data);
247 START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
250 av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
251 "code %02"PRIu32".\n", unit->type);
252 return AVERROR_PATCHWELCOME;
258 static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
259 CodedBitstreamUnit *unit,
262 MPEG2RawSlice *slice = unit->content;
267 err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
272 if (slice->data_size * 8 + 8 > put_bits_left(pbc))
273 return AVERROR(ENOSPC);
275 init_get_bits(&gbc, slice->data, slice->data_size * 8);
276 skip_bits_long(&gbc, slice->data_bit_start);
278 while (get_bits_left(&gbc) > 15)
279 put_bits(pbc, 16, get_bits(&gbc, 16));
281 bits_left = get_bits_left(&gbc);
282 put_bits(pbc, bits_left, get_bits(&gbc, bits_left));
284 // Align with zeroes.
285 while (put_bits_count(pbc) % 8 != 0)
292 static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
293 CodedBitstreamUnit *unit)
295 CodedBitstreamMPEG2Context *priv = ctx->priv_data;
299 if (!priv->write_buffer) {
300 // Initial write buffer size is 1MB.
301 priv->write_buffer_size = 1024 * 1024;
303 reallocate_and_try_again:
304 err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
306 av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
307 "sufficiently large write buffer (last attempt "
308 "%zu bytes).\n", priv->write_buffer_size);
313 init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
315 if (unit->type >= 0x01 && unit->type <= 0xaf)
316 err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
318 err = cbs_mpeg2_write_header(ctx, unit, &pbc);
320 if (err == AVERROR(ENOSPC)) {
322 priv->write_buffer_size *= 2;
323 goto reallocate_and_try_again;
326 // Write failed for some other reason.
330 if (put_bits_count(&pbc) % 8)
331 unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
333 unit->data_bit_padding = 0;
335 unit->data_size = (put_bits_count(&pbc) + 7) / 8;
336 flush_put_bits(&pbc);
338 err = av_reallocp(&unit->data, unit->data_size);
342 memcpy(unit->data, priv->write_buffer, unit->data_size);
347 static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
348 CodedBitstreamFragment *frag)
355 for (i = 0; i < frag->nb_units; i++)
356 size += 3 + frag->units[i].data_size;
358 data = av_malloc(size);
360 return AVERROR(ENOMEM);
363 for (i = 0; i < frag->nb_units; i++) {
364 CodedBitstreamUnit *unit = &frag->units[i];
370 for (sp = 0; sp < unit->data_size; sp++)
371 data[dp++] = unit->data[sp];
374 av_assert0(dp == size);
377 frag->data_size = size;
382 static void cbs_mpeg2_free_unit(CodedBitstreamUnit *unit)
384 if (MPEG2_START_IS_SLICE(unit->type)) {
385 MPEG2RawSlice *slice = unit->content;
386 av_freep(&slice->data);
387 av_freep(&slice->header.extra_information);
388 } else if (unit->type == MPEG2_START_USER_DATA) {
389 MPEG2RawUserData *user = unit->content;
390 av_freep(&user->user_data);
392 av_freep(&unit->content);
395 static void cbs_mpeg2_close(CodedBitstreamContext *ctx)
397 CodedBitstreamMPEG2Context *priv = ctx->priv_data;
399 av_freep(&priv->write_buffer);
402 const CodedBitstreamType ff_cbs_type_mpeg2 = {
403 .codec_id = AV_CODEC_ID_MPEG2VIDEO,
405 .priv_data_size = sizeof(CodedBitstreamMPEG2Context),
407 .split_fragment = &cbs_mpeg2_split_fragment,
408 .read_unit = &cbs_mpeg2_read_unit,
409 .write_unit = &cbs_mpeg2_write_unit,
410 .assemble_fragment = &cbs_mpeg2_assemble_fragment,
412 .free_unit = &cbs_mpeg2_free_unit,
413 .close = &cbs_mpeg2_close,