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FFmpeg/libavcodec/cbs_mpeg2.c
Andreas Rheinhardt 4e7e30bbe0 cbs: Don't set AVBuffer's opaque 
cbs is currently inconsistent regarding the opaque field that can be
used as a special argument to av_buffer_create in order to be used
during freeing the buffer: ff_cbs_alloc_unit_content and all the free
functions used name this parameter as if it should contain a pointer to
the unit whose content is about to be created; but both
ff_cbs_alloc_unit_content as well as ff_cbs_h264_add_sei_message
actually use a pointer to the CodedBitstreamContext as opaque. It should
actually be neither, because it is unneeded (as is evidenced by the fact
that none of the free functions use this pointer at all) and because it
ties the unit's content to the lifetime of other objects, although a
refcounted buffer is supposed to have its own lifetime that only ends
when its reference count reaches zero. This problem manifests itself in
the pointer becoming dangling.
The pointer to the unit can become dangling if another unit is added to
the fragment later as happens in the bitstream filters; in this case,
the pointer can point to the wrong unit (if the fragment's unit array
needn't be relocated) or it can point to where the array was earlier.
It can also become dangling if the unit's content is meant to survive
the resetting of the fragment it was originally read with. This applies
to the extradata of H.264 and HEVC.
The pointer to the context can become dangling if the context is closed
before the content is freed. Although this doesn't seem to happen right
now, it could happen, in particular if one uses different
CodedBitstreamContexts for in- and output.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2019-07-29 22:25:10 +01:00

468 lines
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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, MAX_UINT_BITS(width), 0)
#define uir(width, name) \
xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0)
#define uis(width, name, subs, ...) \
xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
#define uirs(width, name, subs, ...) \
xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
#define xui(width, name, var, range_min, range_max, subs, ...) \
xuia(width, #name, var, range_min, range_max, subs, __VA_ARGS__)
#define sis(width, name, subs, ...) \
xsi(width, name, current->name, subs, __VA_ARGS__)
#define marker_bit() \
bit("marker_bit", 1)
#define bit(string, value) do { \
av_unused uint32_t bit = value; \
xuia(1, string, bit, value, value, 0); \
} while (0)
#define READ
#define READWRITE read
#define RWContext GetBitContext
#define xuia(width, string, var, range_min, range_max, subs, ...) do { \
uint32_t value; \
CHECK(ff_cbs_read_unsigned(ctx, rw, width, string, \
SUBSCRIPTS(subs, __VA_ARGS__), \
&value, range_min, range_max)); \
var = value; \
} while (0)
#define xsi(width, name, var, subs, ...) do { \
int32_t value; \
CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), &value, \
MIN_INT_BITS(width), \
MAX_INT_BITS(width))); \
var = value; \
} while (0)
#define nextbits(width, compare, var) \
(get_bits_left(rw) >= width && \
(var = show_bits(rw, width)) == (compare))
#define infer(name, value) do { \
current->name = value; \
} while (0)
#include "cbs_mpeg2_syntax_template.c"
#undef READ
#undef READWRITE
#undef RWContext
#undef xuia
#undef xsi
#undef nextbits
#undef infer
#define WRITE
#define READWRITE write
#define RWContext PutBitContext
#define xuia(width, string, var, range_min, range_max, subs, ...) do { \
CHECK(ff_cbs_write_unsigned(ctx, rw, width, string, \
SUBSCRIPTS(subs, __VA_ARGS__), \
var, range_min, range_max)); \
} while (0)
#define xsi(width, name, var, subs, ...) do { \
CHECK(ff_cbs_write_signed(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), var, \
MIN_INT_BITS(width), \
MAX_INT_BITS(width))); \
} while (0)
#define nextbits(width, compare, var) (var)
#define infer(name, value) do { \
if (current->name != (value)) { \
av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
"%s does not match inferred value: " \
"%"PRId64", but should be %"PRId64".\n", \
#name, (int64_t)current->name, (int64_t)(value)); \
} \
} while (0)
#include "cbs_mpeg2_syntax_template.c"
#undef WRITE
#undef READWRITE
#undef RWContext
#undef xuia
#undef xsi
#undef nextbits
#undef infer
static void cbs_mpeg2_free_picture_header(void *opaque, uint8_t *content)
{
MPEG2RawPictureHeader *picture = (MPEG2RawPictureHeader*)content;
av_buffer_unref(&picture->extra_information_picture.extra_information_ref);
av_freep(&content);
}
static void cbs_mpeg2_free_user_data(void *opaque, uint8_t *content)
{
MPEG2RawUserData *user = (MPEG2RawUserData*)content;
av_buffer_unref(&user->user_data_ref);
av_freep(&content);
}
static void cbs_mpeg2_free_slice(void *opaque, uint8_t *content)
{
MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
av_buffer_unref(&slice->header.extra_information_slice.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(MPEG2_START_PICTURE, MPEG2RawPictureHeader,
picture_header, &cbs_mpeg2_free_picture_header);
START(MPEG2_START_USER_DATA, MPEG2RawUserData,
user_data, &cbs_mpeg2_free_user_data);
START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader,
sequence_header, NULL);
START(MPEG2_START_EXTENSION, MPEG2RawExtensionData,
extension_data, NULL);
START(MPEG2_START_GROUP, MPEG2RawGroupOfPicturesHeader,
group_of_pictures_header, NULL);
#undef START
default:
return AVERROR(ENOSYS);
}
}
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(MPEG2_START_PICTURE, MPEG2RawPictureHeader, picture_header);
START(MPEG2_START_USER_DATA, MPEG2RawUserData, user_data);
START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader, sequence_header);
START(MPEG2_START_EXTENSION, MPEG2RawExtensionData, extension_data);
START(MPEG2_START_GROUP, 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;
int err;
err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
if (err < 0)
return err;
if (slice->data) {
size_t rest = slice->data_size - (slice->data_bit_start + 7) / 8;
uint8_t *pos = slice->data + slice->data_bit_start / 8;
av_assert0(slice->data_bit_start >= 0 &&
8 * slice->data_size > slice->data_bit_start);
if (slice->data_size * 8 + 8 > put_bits_left(pbc))
return AVERROR(ENOSPC);
// First copy the remaining bits of the first byte
if (slice->data_bit_start % 8)
put_bits(pbc, 8 - slice->data_bit_start % 8,
*pos++ & MAX_UINT_BITS(8 - slice->data_bit_start % 8));
if (put_bits_count(pbc) % 8 == 0) {
// If the writer is aligned at this point,
// memcpy can be used to improve performance.
// This is the normal case.
flush_put_bits(pbc);
memcpy(put_bits_ptr(pbc), pos, rest);
skip_put_bytes(pbc, rest);
} else {
// If not, we have to copy manually:
for (; rest > 3; rest -= 4, pos += 4)
put_bits32(pbc, AV_RB32(pos));
for (; rest; rest--, pos++)
put_bits(pbc, 8, *pos);
// Align with zeros
put_bits(pbc, 8 - put_bits_count(pbc) % 8, 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 (MPEG2_START_IS_SLICE(unit->type))
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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