FFmpeg/libavcodec/cbs_vp8.c
Dai, Jianhui J 61afe4d98c avcodec/cbs_vp8: Improve the bitstream position check
The VP8 compressed header may not be byte-aligned due to boolean
coding. Round up byte count for accurate data positioning.

Signed-off-by: Jianhui Dai <jianhui.j.dai@intel.com>
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
2024-03-26 09:05:04 -04:00

387 lines
10 KiB
C

/*
* 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_vp8.h"
#include <stdbool.h>
#define DEFAULT_PROB 0x80
// The probability table is defined in 'vp8data.c'.
extern const uint8_t ff_vp8_token_update_probs[4][8][3][11];
// Implements VP8 boolean decoder using GetBitContext to read the bitstream.
typedef struct CBSVP8BoolDecoder {
GetBitContext *gbc;
uint8_t value;
uint8_t range;
uint8_t count; // Store the number of bits in the `value` buffer.
} CBSVP8BoolDecoder;
static int cbs_vp8_bool_decoder_init(CBSVP8BoolDecoder *decoder, GetBitContext *gbc)
{
av_assert0(decoder);
av_assert0(gbc);
decoder->gbc = gbc;
decoder->value = 0;
decoder->range = 255;
decoder->count = 0;
return 0;
}
static bool cbs_vp8_bool_decoder_fill_value(CBSVP8BoolDecoder *decoder)
{
int bits = 8 - decoder->count;
av_assert0(decoder->count <= 8);
if (decoder->count == 8) {
return true;
}
if (get_bits_left(decoder->gbc) >= bits) {
decoder->value |= get_bits(decoder->gbc, bits);
decoder->count += bits;
}
return (decoder->count == 8);
}
static int cbs_vp8_bool_decoder_read_bool(CBSVP8BoolDecoder *decoder,
const uint8_t prob, uint8_t *output)
{
uint8_t split = 1 + (((decoder->range - 1) * prob) >> 8);
if (!cbs_vp8_bool_decoder_fill_value(decoder)) {
return AVERROR_INVALIDDATA;
}
av_assert0(decoder->count == 8);
if (decoder->value >= split) {
*output = 1;
decoder->range -= split;
decoder->value -= split;
} else {
*output = 0;
decoder->range = split;
}
while (decoder->range < 128) {
decoder->value <<= 1;
decoder->range <<= 1;
--decoder->count;
}
return 0;
}
static int cbs_vp8_bool_decoder_read_literal(CBSVP8BoolDecoder *decoder,
const uint8_t prob,
uint32_t num_bits,
uint32_t *output)
{
int ret = 0;
av_assert0(num_bits <= 32);
*output = 0;
for (; num_bits > 0; --num_bits) {
uint8_t bit_output = 0;
if ((ret = cbs_vp8_bool_decoder_read_bool(decoder, prob,
&bit_output)) != 0) {
return ret;
}
*output = (*output << 1) | bit_output;
}
return 0;
}
static int cbs_vp8_bool_decoder_read_unsigned(
CodedBitstreamContext *ctx, CBSVP8BoolDecoder *bool_decoder, int width,
uint8_t prob, const char *name, const int *subscripts, uint32_t *write_to,
bool trace_enable)
{
int ret = 0;
GetBitContext *gbc = bool_decoder->gbc;
uint32_t value;
CBS_TRACE_READ_START();
av_assert0(width >= 0 && width <= 8);
ret = cbs_vp8_bool_decoder_read_literal(bool_decoder, prob, width, &value);
if (ret != 0) {
return ret;
}
if (trace_enable) {
CBS_TRACE_READ_END();
}
*write_to = value;
return 0;
}
static int cbs_vp8_bool_decoder_read_signed(
CodedBitstreamContext *ctx, CBSVP8BoolDecoder *bool_decoder, int width,
uint8_t prob, const char *name, const int *subscripts, int32_t *write_to)
{
int ret = 0;
GetBitContext *gbc = bool_decoder->gbc;
int32_t value;
uint8_t sign = 0;
CBS_TRACE_READ_START();
av_assert0(width >= 0 && width <= 8);
ret = cbs_vp8_bool_decoder_read_literal(bool_decoder, prob, width, &value);
if (ret != 0) {
return ret;
}
ret = cbs_vp8_bool_decoder_read_bool(bool_decoder, prob, &sign);
if (ret != 0) {
return ret;
}
if (sign) {
value = -value;
}
CBS_TRACE_READ_END();
*write_to = value;
return 0;
}
static int cbs_vp8_read_unsigned_le(CodedBitstreamContext *ctx,
GetBitContext *gbc, int width,
const char *name, const int *subscripts,
uint32_t *write_to, uint32_t range_min,
uint32_t range_max)
{
int32_t value;
CBS_TRACE_READ_START();
av_assert0(width > 0 && width <= 24);
if (get_bits_left(gbc) < width) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid value: bitstream ended.\n");
return AVERROR_INVALIDDATA;
}
value = get_bits_le(gbc, width);
CBS_TRACE_READ_END();
if (value < range_min || value > range_max) {
av_log(ctx->log_ctx, AV_LOG_ERROR,
"%s out of range: "
"%" PRIu32 ", but must be in [%" PRIu32 ",%" PRIu32 "].\n",
name, value, range_min, range_max);
return AVERROR_INVALIDDATA;
}
*write_to = value;
return 0;
}
#define HEADER(name) \
do { \
ff_cbs_trace_header(ctx, name); \
} while (0)
#define CHECK(call) \
do { \
int err = (call); \
if (err < 0) \
return err; \
} while (0)
#define FUNC_NAME(rw, codec, name) cbs_##codec##_##rw##_##name
#define FUNC_VP8(rw, name) FUNC_NAME(rw, vp8, name)
#define FUNC(name) FUNC_VP8(READWRITE, name)
#define SUBSCRIPTS(subs, ...) \
(subs > 0 ? ((int[subs + 1]){subs, __VA_ARGS__}) : NULL)
#define f(width, name) xf(width, name, 0, )
// bool [de|en]coder methods.
#define bc_f(width, name) bc_unsigned_subs(width, DEFAULT_PROB, true, name, 0, )
#define bc_s(width, name) bc_signed_subs(width, DEFAULT_PROB, name, 0, )
#define bc_fs(width, name, subs, ...) \
bc_unsigned_subs(width, DEFAULT_PROB, true, name, subs, __VA_ARGS__)
#define bc_ss(width, name, subs, ...) \
bc_signed_subs(width, DEFAULT_PROB, name, subs, __VA_ARGS__)
// bool [de|en]coder methods for boolean value and disable tracing.
#define bc_b(name) bc_unsigned_subs(1, DEFAULT_PROB, false, name, 0, )
#define bc_b_prob(prob, name) bc_unsigned_subs(1, prob, false, name, 0, )
#define READ
#define READWRITE read
#define RWContext GetBitContext
#define CBSVP8BoolCodingRW CBSVP8BoolDecoder
#define xf(width, name, subs, ...) \
do { \
uint32_t value; \
CHECK(cbs_vp8_read_unsigned_le(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), &value, \
0, MAX_UINT_BITS(width))); \
current->name = value; \
} while (0)
#define fixed(width, name, value) \
do { \
uint32_t fixed_value; \
CHECK(cbs_vp8_read_unsigned_le(ctx, rw, width, #name, 0, &fixed_value, \
value, value)); \
} while (0)
#define bc_unsigned_subs(width, prob, enable_trace, name, subs, ...) \
do { \
uint32_t value; \
CHECK(cbs_vp8_bool_decoder_read_unsigned( \
ctx, bool_coding_rw, width, prob, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), &value, enable_trace)); \
current->name = value; \
} while (0)
#define bc_signed_subs(width, prob, name, subs, ...) \
do { \
int32_t value; \
CHECK(cbs_vp8_bool_decoder_read_signed( \
ctx, bool_coding_rw, width, prob, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), &value)); \
current->name = value; \
} while (0)
#include "cbs_vp8_syntax_template.c"
static int cbs_vp8_split_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag, int header)
{
int err;
if (frag->data_size == 0)
return AVERROR_INVALIDDATA;
err = ff_cbs_append_unit_data(frag, 0, frag->data, frag->data_size,
frag->data_ref);
if (err < 0)
return err;
return 0;
}
static int cbs_vp8_read_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
VP8RawFrame *frame;
GetBitContext gbc;
CBSVP8BoolDecoder bool_decoder;
int err, pos;
err = ff_cbs_alloc_unit_content(ctx, unit);
if (err < 0)
return err;
frame = unit->content;
// Create GetBitContext for uncompressed header.
err = init_get_bits8_le(&gbc, unit->data, unit->data_size);
if (err < 0)
return err;
err = cbs_vp8_read_uncompressed_header(ctx, &gbc, frame);
if (err < 0)
return err;
pos = get_bits_count(&gbc);
av_assert0(pos % 8 == 0);
// Create boolean decoder for compressed header.
err = cbs_vp8_bool_decoder_init(&bool_decoder, &gbc);
if (err < 0)
return err;
err = cbs_vp8_read_compressed_header(ctx, &bool_decoder, frame);
if (err < 0)
return err;
pos = get_bits_count(&gbc);
// Position may not be byte-aligned after compressed header; Round up byte
// count for accurate data positioning.
pos = (pos + 7) / 8;
av_assert0(pos <= unit->data_size);
frame->data_ref = av_buffer_ref(unit->data_ref);
if (!frame->data_ref)
return AVERROR(ENOMEM);
frame->data = unit->data + pos;
frame->data_size = unit->data_size - pos;
return 0;
}
static int cbs_vp8_write_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit, PutBitContext *pbc)
{
return AVERROR_PATCHWELCOME;
}
static int cbs_vp8_assemble_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
return AVERROR_PATCHWELCOME;
}
static const CodedBitstreamUnitTypeDescriptor cbs_vp8_unit_types[] = {
CBS_UNIT_TYPE_INTERNAL_REF(0, VP8RawFrame, data),
CBS_UNIT_TYPE_END_OF_LIST,
};
const CodedBitstreamType ff_cbs_type_vp8 = {
.codec_id = AV_CODEC_ID_VP8,
.priv_data_size = 0,
.unit_types = cbs_vp8_unit_types,
.split_fragment = &cbs_vp8_split_fragment,
.read_unit = &cbs_vp8_read_unit,
.write_unit = &cbs_vp8_write_unit,
.assemble_fragment = &cbs_vp8_assemble_fragment,
};