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 void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
107 MPEG2RawUserData *user = (MPEG2RawUserData*)content;
108 av_buffer_unref(&user->user_data_ref);
112 static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
114 MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
115 av_buffer_unref(&slice->header.extra_information_ref);
116 av_buffer_unref(&slice->data_ref);
120 static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
121 CodedBitstreamFragment *frag,
124 const uint8_t *start, *end;
126 uint32_t start_code = -1, next_start_code = -1;
128 int err, i, unit_type;
130 start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
133 end = avpriv_find_start_code(start, frag->data + frag->data_size,
136 unit_type = start_code & 0xff;
138 // The start and end pointers point at to the byte following the
139 // start_code_identifier in the start code that they found.
140 if (end == frag->data + frag->data_size) {
141 // We didn't find a start code, so this is the final unit.
142 unit_size = end - (start - 1);
144 // Unit runs from start to the beginning of the start code
145 // pointed to by end (including any padding zeroes).
146 unit_size = (end - 4) - (start - 1);
149 unit_data = av_malloc(unit_size + AV_INPUT_BUFFER_PADDING_SIZE);
151 return AVERROR(ENOMEM);
152 memcpy(unit_data, start - 1, unit_size);
153 memset(unit_data + unit_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
155 err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
156 unit_data, unit_size, NULL);
158 av_freep(&unit_data);
162 if (end == frag->data + frag->data_size)
165 start_code = next_start_code;
172 static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
173 CodedBitstreamUnit *unit)
178 err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
182 if (MPEG2_START_IS_SLICE(unit->type)) {
183 MPEG2RawSlice *slice;
186 err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*slice),
187 &cbs_mpeg2_free_slice);
190 slice = unit->content;
192 err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
196 pos = get_bits_count(&gbc);
197 len = unit->data_size;
199 slice->data_size = len - pos / 8;
200 slice->data_ref = av_buffer_alloc(slice->data_size +
201 AV_INPUT_BUFFER_PADDING_SIZE);
202 if (!slice->data_ref)
203 return AVERROR(ENOMEM);
204 slice->data = slice->data_ref->data;
207 unit->data + pos / 8, slice->data_size);
208 memset(slice->data + slice->data_size, 0,
209 AV_INPUT_BUFFER_PADDING_SIZE);
210 slice->data_bit_start = pos % 8;
213 switch (unit->type) {
214 #define START(start_code, type, read_func, free_func) \
218 err = ff_cbs_alloc_unit_content(ctx, unit, \
219 sizeof(*header), free_func); \
222 header = unit->content; \
223 err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
228 START(0x00, MPEG2RawPictureHeader, picture_header, NULL);
229 START(0xb2, MPEG2RawUserData, user_data,
230 &cbs_mpeg2_free_user_data);
231 START(0xb3, MPEG2RawSequenceHeader, sequence_header, NULL);
232 START(0xb5, MPEG2RawExtensionData, extension_data, NULL);
233 START(0xb8, MPEG2RawGroupOfPicturesHeader,
234 group_of_pictures_header, NULL);
237 av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %02"PRIx32".\n",
239 return AVERROR_INVALIDDATA;
246 static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
247 CodedBitstreamUnit *unit,
252 switch (unit->type) {
253 #define START(start_code, type, func) \
255 err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
257 START(0x00, MPEG2RawPictureHeader, picture_header);
258 START(0xb2, MPEG2RawUserData, user_data);
259 START(0xb3, MPEG2RawSequenceHeader, sequence_header);
260 START(0xb5, MPEG2RawExtensionData, extension_data);
261 START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
264 av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
265 "code %02"PRIx32".\n", unit->type);
266 return AVERROR_PATCHWELCOME;
272 static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
273 CodedBitstreamUnit *unit,
276 MPEG2RawSlice *slice = unit->content;
281 err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
286 if (slice->data_size * 8 + 8 > put_bits_left(pbc))
287 return AVERROR(ENOSPC);
289 init_get_bits(&gbc, slice->data, slice->data_size * 8);
290 skip_bits_long(&gbc, slice->data_bit_start);
292 while (get_bits_left(&gbc) > 15)
293 put_bits(pbc, 16, get_bits(&gbc, 16));
295 bits_left = get_bits_left(&gbc);
296 put_bits(pbc, bits_left, get_bits(&gbc, bits_left));
298 // Align with zeroes.
299 while (put_bits_count(pbc) % 8 != 0)
306 static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
307 CodedBitstreamUnit *unit)
309 CodedBitstreamMPEG2Context *priv = ctx->priv_data;
313 if (!priv->write_buffer) {
314 // Initial write buffer size is 1MB.
315 priv->write_buffer_size = 1024 * 1024;
317 reallocate_and_try_again:
318 err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
320 av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
321 "sufficiently large write buffer (last attempt "
322 "%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
327 init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
329 if (unit->type >= 0x01 && unit->type <= 0xaf)
330 err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
332 err = cbs_mpeg2_write_header(ctx, unit, &pbc);
334 if (err == AVERROR(ENOSPC)) {
336 priv->write_buffer_size *= 2;
337 goto reallocate_and_try_again;
340 // Write failed for some other reason.
344 if (put_bits_count(&pbc) % 8)
345 unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
347 unit->data_bit_padding = 0;
349 unit->data_size = (put_bits_count(&pbc) + 7) / 8;
350 flush_put_bits(&pbc);
352 err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
356 memcpy(unit->data, priv->write_buffer, unit->data_size);
361 static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
362 CodedBitstreamFragment *frag)
369 for (i = 0; i < frag->nb_units; i++)
370 size += 3 + frag->units[i].data_size;
372 frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
374 return AVERROR(ENOMEM);
375 data = frag->data_ref->data;
378 for (i = 0; i < frag->nb_units; i++) {
379 CodedBitstreamUnit *unit = &frag->units[i];
385 for (sp = 0; sp < unit->data_size; sp++)
386 data[dp++] = unit->data[sp];
389 av_assert0(dp == size);
391 memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
393 frag->data_size = size;
398 static void cbs_mpeg2_close(CodedBitstreamContext *ctx)
400 CodedBitstreamMPEG2Context *priv = ctx->priv_data;
402 av_freep(&priv->write_buffer);
405 const CodedBitstreamType ff_cbs_type_mpeg2 = {
406 .codec_id = AV_CODEC_ID_MPEG2VIDEO,
408 .priv_data_size = sizeof(CodedBitstreamMPEG2Context),
410 .split_fragment = &cbs_mpeg2_split_fragment,
411 .read_unit = &cbs_mpeg2_read_unit,
412 .write_unit = &cbs_mpeg2_write_unit,
413 .assemble_fragment = &cbs_mpeg2_assemble_fragment,
415 .close = &cbs_mpeg2_close,