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ffmpeg/libavcodec/cbs_mpeg2.c

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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "cbs.h"
#include "cbs_internal.h"
#include "cbs_mpeg2.h"
#include "internal.h"
#define HEADER(name) do { \
ff_cbs_trace_header(ctx, name); \
} while (0)
#define CHECK(call) do { \
err = (call); \
if (err < 0) \
return err; \
} while (0)
#define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
#define FUNC_MPEG2(rw, name) FUNC_NAME(rw, mpeg2, name)
#define FUNC(name) FUNC_MPEG2(READWRITE, name)
#define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
#define ui(width, name) \
xui(width, name, current->name, 0)
#define uis(width, name, subs, ...) \
xui(width, name, current->name, subs, __VA_ARGS__)
#define READ
#define READWRITE read
#define RWContext GetBitContext
#define xui(width, name, var, subs, ...) do { \
uint32_t value = 0; \
CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), \
&value, 0, (1 << width) - 1)); \
var = value; \
} while (0)
#define marker_bit() do { \
av_unused uint32_t one; \
CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", NULL, &one, 1, 1)); \
} while (0)
#define nextbits(width, compare, var) \
(get_bits_left(rw) >= width && \
(var = show_bits(rw, width)) == (compare))
#include "cbs_mpeg2_syntax_template.c"
#undef READ
#undef READWRITE
#undef RWContext
#undef xui
#undef marker_bit
#undef nextbits
#define WRITE
#define READWRITE write
#define RWContext PutBitContext
#define xui(width, name, var, subs, ...) do { \
CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), \
var, 0, (1 << width) - 1)); \
} while (0)
#define marker_bit() do { \
CHECK(ff_cbs_write_unsigned(ctx, rw, 1, "marker_bit", NULL, 1, 1, 1)); \
} while (0)
#define nextbits(width, compare, var) (var)
#include "cbs_mpeg2_syntax_template.c"
#undef READ
#undef READWRITE
#undef RWContext
#undef xui
#undef marker_bit
#undef nextbits
static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
{
MPEG2RawUserData *user = (MPEG2RawUserData*)content;
av_buffer_unref(&user->user_data_ref);
av_freep(&content);
}
static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
{
MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
av_buffer_unref(&slice->header.extra_information_ref);
av_buffer_unref(&slice->data_ref);
av_freep(&content);
}
static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int header)
{
const uint8_t *start, *end;
uint8_t *unit_data;
uint32_t start_code = -1, next_start_code = -1;
size_t unit_size;
int err, i, unit_type;
start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
&start_code);
for (i = 0;; i++) {
end = avpriv_find_start_code(start, frag->data + frag->data_size,
&next_start_code);
unit_type = start_code & 0xff;
// The start and end pointers point at to the byte following the
// start_code_identifier in the start code that they found.
if (end == frag->data + frag->data_size) {
// We didn't find a start code, so this is the final unit.
unit_size = end - (start - 1);
} else {
// Unit runs from start to the beginning of the start code
// pointed to by end (including any padding zeroes).
unit_size = (end - 4) - (start - 1);
}
unit_data = (uint8_t *)start - 1;
err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
unit_data, unit_size, frag->data_ref);
if (err < 0)
return err;
if (end == frag->data + frag->data_size)
break;
start_code = next_start_code;
start = end;
}
return 0;
}
static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
GetBitContext gbc;
int err;
err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
if (err < 0)
return err;
if (MPEG2_START_IS_SLICE(unit->type)) {
MPEG2RawSlice *slice;
int pos, len;
err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*slice),
&cbs_mpeg2_free_slice);
if (err < 0)
return err;
slice = unit->content;
err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
if (err < 0)
return err;
pos = get_bits_count(&gbc);
len = unit->data_size;
slice->data_size = len - pos / 8;
slice->data_ref = av_buffer_ref(unit->data_ref);
if (!slice->data_ref)
return AVERROR(ENOMEM);
slice->data = unit->data + pos / 8;
slice->data_bit_start = pos % 8;
} else {
switch (unit->type) {
#define START(start_code, type, read_func, free_func) \
case start_code: \
{ \
type *header; \
err = ff_cbs_alloc_unit_content(ctx, unit, \
sizeof(*header), free_func); \
if (err < 0) \
return err; \
header = unit->content; \
err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
if (err < 0) \
return err; \
} \
break;
START(0x00, MPEG2RawPictureHeader, picture_header, NULL);
START(0xb2, MPEG2RawUserData, user_data,
&cbs_mpeg2_free_user_data);
START(0xb3, MPEG2RawSequenceHeader, sequence_header, NULL);
START(0xb5, MPEG2RawExtensionData, extension_data, NULL);
START(0xb8, MPEG2RawGroupOfPicturesHeader,
group_of_pictures_header, NULL);
#undef START
default:
av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %02"PRIx32".\n",
unit->type);
return AVERROR_INVALIDDATA;
}
}
return 0;
}
static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
int err;
switch (unit->type) {
#define START(start_code, type, func) \
case start_code: \
err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
break;
START(0x00, MPEG2RawPictureHeader, picture_header);
START(0xb2, MPEG2RawUserData, user_data);
START(0xb3, MPEG2RawSequenceHeader, sequence_header);
START(0xb5, MPEG2RawExtensionData, extension_data);
START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
#undef START
default:
av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
"code %02"PRIx32".\n", unit->type);
return AVERROR_PATCHWELCOME;
}
return err;
}
static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
MPEG2RawSlice *slice = unit->content;
GetBitContext gbc;
size_t bits_left;
int err;
err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
if (err < 0)
return err;
if (slice->data) {
if (slice->data_size * 8 + 8 > put_bits_left(pbc))
return AVERROR(ENOSPC);
init_get_bits(&gbc, slice->data, slice->data_size * 8);
skip_bits_long(&gbc, slice->data_bit_start);
while (get_bits_left(&gbc) > 15)
put_bits(pbc, 16, get_bits(&gbc, 16));
bits_left = get_bits_left(&gbc);
put_bits(pbc, bits_left, get_bits(&gbc, bits_left));
// Align with zeroes.
while (put_bits_count(pbc) % 8 != 0)
put_bits(pbc, 1, 0);
}
return 0;
}
static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
CodedBitstreamMPEG2Context *priv = ctx->priv_data;
PutBitContext pbc;
int err;
if (!priv->write_buffer) {
// Initial write buffer size is 1MB.
priv->write_buffer_size = 1024 * 1024;
reallocate_and_try_again:
err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
if (err < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
"sufficiently large write buffer (last attempt "
"%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
return err;
}
}
init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
if (unit->type >= 0x01 && unit->type <= 0xaf)
err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
else
err = cbs_mpeg2_write_header(ctx, unit, &pbc);
if (err == AVERROR(ENOSPC)) {
// Overflow.
priv->write_buffer_size *= 2;
goto reallocate_and_try_again;
}
if (err < 0) {
// Write failed for some other reason.
return err;
}
if (put_bits_count(&pbc) % 8)
unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
else
unit->data_bit_padding = 0;
unit->data_size = (put_bits_count(&pbc) + 7) / 8;
flush_put_bits(&pbc);
err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
if (err < 0)
return err;
memcpy(unit->data, priv->write_buffer, unit->data_size);
return 0;
}
static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
uint8_t *data;
size_t size, dp;
int i;
size = 0;
for (i = 0; i < frag->nb_units; i++)
size += 3 + frag->units[i].data_size;
frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!frag->data_ref)
return AVERROR(ENOMEM);
data = frag->data_ref->data;
dp = 0;
for (i = 0; i < frag->nb_units; i++) {
CodedBitstreamUnit *unit = &frag->units[i];
data[dp++] = 0;
data[dp++] = 0;
data[dp++] = 1;
memcpy(data + dp, unit->data, unit->data_size);
dp += unit->data_size;
}
av_assert0(dp == size);
memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
frag->data = data;
frag->data_size = size;
return 0;
}
static void cbs_mpeg2_close(CodedBitstreamContext *ctx)
{
CodedBitstreamMPEG2Context *priv = ctx->priv_data;
av_freep(&priv->write_buffer);
}
const CodedBitstreamType ff_cbs_type_mpeg2 = {
.codec_id = AV_CODEC_ID_MPEG2VIDEO,
.priv_data_size = sizeof(CodedBitstreamMPEG2Context),
.split_fragment = &cbs_mpeg2_split_fragment,
.read_unit = &cbs_mpeg2_read_unit,
.write_unit = &cbs_mpeg2_write_unit,
.assemble_fragment = &cbs_mpeg2_assemble_fragment,
.close = &cbs_mpeg2_close,
};
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