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FFmpeg/libavcodec/h2645_parse.c
Michael Niedermayer 7562567f41 avcodec/h2645_parse: Replace RNXYA by RNXY in ff_h2645_extract_rbsp() 
Fixes misaligned accesses
Found-by: Matt Wolenetz <wolenetz@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2018-04-25 23:09:47 +02:00

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/*
* H.264/HEVC common parsing code
*
* 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 <string.h>
#include "config.h"
#include "libavutil/intmath.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#include "bytestream.h"
#include "hevc.h"
#include "h2645_parse.h"
int ff_h2645_extract_rbsp(const uint8_t *src, int length,
H2645RBSP *rbsp, H2645NAL *nal, int small_padding)
{
int i, si, di;
uint8_t *dst;
nal->skipped_bytes = 0;
#define STARTCODE_TEST \
if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) { \
if (src[i + 2] != 3 && src[i + 2] != 0) { \
/* startcode, so we must be past the end */ \
length = i; \
} \
break; \
}
#if HAVE_FAST_UNALIGNED
#define FIND_FIRST_ZERO \
if (i > 0 && !src[i]) \
i--; \
while (src[i]) \
i++
#if HAVE_FAST_64BIT
for (i = 0; i + 1 < length; i += 9) {
if (!((~AV_RN64(src + i) &
(AV_RN64(src + i) - 0x0100010001000101ULL)) &
0x8000800080008080ULL))
continue;
FIND_FIRST_ZERO;
STARTCODE_TEST;
i -= 7;
}
#else
for (i = 0; i + 1 < length; i += 5) {
if (!((~AV_RN32(src + i) &
(AV_RN32(src + i) - 0x01000101U)) &
0x80008080U))
continue;
FIND_FIRST_ZERO;
STARTCODE_TEST;
i -= 3;
}
#endif /* HAVE_FAST_64BIT */
#else
for (i = 0; i + 1 < length; i += 2) {
if (src[i])
continue;
if (i > 0 && src[i - 1] == 0)
i--;
STARTCODE_TEST;
}
#endif /* HAVE_FAST_UNALIGNED */
if (i >= length - 1 && small_padding) { // no escaped 0
nal->data =
nal->raw_data = src;
nal->size =
nal->raw_size = length;
return length;
} else if (i > length)
i = length;
nal->rbsp_buffer = &rbsp->rbsp_buffer[rbsp->rbsp_buffer_size];
dst = nal->rbsp_buffer;
memcpy(dst, src, i);
si = di = i;
while (si + 2 < length) {
// remove escapes (very rare 1:2^22)
if (src[si + 2] > 3) {
dst[di++] = src[si++];
dst[di++] = src[si++];
} else if (src[si] == 0 && src[si + 1] == 0 && src[si + 2] != 0) {
if (src[si + 2] == 3) { // escape
dst[di++] = 0;
dst[di++] = 0;
si += 3;
if (nal->skipped_bytes_pos) {
nal->skipped_bytes++;
if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
nal->skipped_bytes_pos_size *= 2;
av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
av_reallocp_array(&nal->skipped_bytes_pos,
nal->skipped_bytes_pos_size,
sizeof(*nal->skipped_bytes_pos));
if (!nal->skipped_bytes_pos) {
nal->skipped_bytes_pos_size = 0;
return AVERROR(ENOMEM);
}
}
if (nal->skipped_bytes_pos)
nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;
}
continue;
} else // next start code
goto nsc;
}
dst[di++] = src[si++];
}
while (si < length)
dst[di++] = src[si++];
nsc:
memset(dst + di, 0, AV_INPUT_BUFFER_PADDING_SIZE);
nal->data = dst;
nal->size = di;
nal->raw_data = src;
nal->raw_size = si;
rbsp->rbsp_buffer_size += si;
return si;
}
static const char *nal_unit_name(int nal_type)
{
switch(nal_type) {
case HEVC_NAL_TRAIL_N : return "TRAIL_N";
case HEVC_NAL_TRAIL_R : return "TRAIL_R";
case HEVC_NAL_TSA_N : return "TSA_N";
case HEVC_NAL_TSA_R : return "TSA_R";
case HEVC_NAL_STSA_N : return "STSA_N";
case HEVC_NAL_STSA_R : return "STSA_R";
case HEVC_NAL_RADL_N : return "RADL_N";
case HEVC_NAL_RADL_R : return "RADL_R";
case HEVC_NAL_RASL_N : return "RASL_N";
case HEVC_NAL_RASL_R : return "RASL_R";
case HEVC_NAL_BLA_W_LP : return "BLA_W_LP";
case HEVC_NAL_BLA_W_RADL : return "BLA_W_RADL";
case HEVC_NAL_BLA_N_LP : return "BLA_N_LP";
case HEVC_NAL_IDR_W_RADL : return "IDR_W_RADL";
case HEVC_NAL_IDR_N_LP : return "IDR_N_LP";
case HEVC_NAL_CRA_NUT : return "CRA_NUT";
case HEVC_NAL_VPS : return "VPS";
case HEVC_NAL_SPS : return "SPS";
case HEVC_NAL_PPS : return "PPS";
case HEVC_NAL_AUD : return "AUD";
case HEVC_NAL_EOS_NUT : return "EOS_NUT";
case HEVC_NAL_EOB_NUT : return "EOB_NUT";
case HEVC_NAL_FD_NUT : return "FD_NUT";
case HEVC_NAL_SEI_PREFIX : return "SEI_PREFIX";
case HEVC_NAL_SEI_SUFFIX : return "SEI_SUFFIX";
default : return "?";
}
}
static int get_bit_length(H2645NAL *nal, int skip_trailing_zeros)
{
int size = nal->size;
int v;
while (skip_trailing_zeros && size > 0 && nal->data[size - 1] == 0)
size--;
if (!size)
return 0;
v = nal->data[size - 1];
if (size > INT_MAX / 8)
return AVERROR(ERANGE);
size *= 8;
/* remove the stop bit and following trailing zeros,
* or nothing for damaged bitstreams */
if (v)
size -= ff_ctz(v) + 1;
return size;
}
/**
* @return AVERROR_INVALIDDATA if the packet is not a valid NAL unit,
* 0 if the unit should be skipped, 1 otherwise
*/
static int hevc_parse_nal_header(H2645NAL *nal, void *logctx)
{
GetBitContext *gb = &nal->gb;
int nuh_layer_id;
if (get_bits1(gb) != 0)
return AVERROR_INVALIDDATA;
nal->type = get_bits(gb, 6);
nuh_layer_id = get_bits(gb, 6);
nal->temporal_id = get_bits(gb, 3) - 1;
if (nal->temporal_id < 0)
return AVERROR_INVALIDDATA;
av_log(logctx, AV_LOG_DEBUG,
"nal_unit_type: %d(%s), nuh_layer_id: %d, temporal_id: %d\n",
nal->type, nal_unit_name(nal->type), nuh_layer_id, nal->temporal_id);
return nuh_layer_id == 0;
}
static int h264_parse_nal_header(H2645NAL *nal, void *logctx)
{
GetBitContext *gb = &nal->gb;
if (get_bits1(gb) != 0)
return AVERROR_INVALIDDATA;
nal->ref_idc = get_bits(gb, 2);
nal->type = get_bits(gb, 5);
av_log(logctx, AV_LOG_DEBUG,
"nal_unit_type: %d, nal_ref_idc: %d\n",
nal->type, nal->ref_idc);
return 1;
}
static int find_next_start_code(const uint8_t *buf, const uint8_t *next_avc)
{
int i = 0;
if (buf + 3 >= next_avc)
return next_avc - buf;
while (buf + i + 3 < next_avc) {
if (buf[i] == 0 && buf[i + 1] == 0 && buf[i + 2] == 1)
break;
i++;
}
return i + 3;
}
int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
void *logctx, int is_nalff, int nal_length_size,
enum AVCodecID codec_id, int small_padding)
{
GetByteContext bc;
int consumed, ret = 0;
int next_avc = is_nalff ? 0 : length;
int64_t padding = small_padding ? 0 : MAX_MBPAIR_SIZE;
bytestream2_init(&bc, buf, length);
av_fast_padded_malloc(&pkt->rbsp.rbsp_buffer, &pkt->rbsp.rbsp_buffer_alloc_size, length + padding);
if (!pkt->rbsp.rbsp_buffer)
return AVERROR(ENOMEM);
pkt->rbsp.rbsp_buffer_size = 0;
pkt->nb_nals = 0;
while (bytestream2_get_bytes_left(&bc) >= 4) {
H2645NAL *nal;
int extract_length = 0;
int skip_trailing_zeros = 1;
if (bytestream2_tell(&bc) == next_avc) {
int i = 0;
extract_length = get_nalsize(nal_length_size,
bc.buffer, bytestream2_get_bytes_left(&bc), &i, logctx);
if (extract_length < 0)
return extract_length;
bytestream2_skip(&bc, nal_length_size);
next_avc = bytestream2_tell(&bc) + extract_length;
} else {
int buf_index;
if (bytestream2_tell(&bc) > next_avc)
av_log(logctx, AV_LOG_WARNING, "Exceeded next NALFF position, re-syncing.\n");
/* search start code */
buf_index = find_next_start_code(bc.buffer, buf + next_avc);
bytestream2_skip(&bc, buf_index);
if (!bytestream2_get_bytes_left(&bc)) {
if (pkt->nb_nals > 0) {
// No more start codes: we discarded some irrelevant
// bytes at the end of the packet.
return 0;
} else {
av_log(logctx, AV_LOG_ERROR, "No start code is found.\n");
return AVERROR_INVALIDDATA;
}
}
extract_length = FFMIN(bytestream2_get_bytes_left(&bc), next_avc - bytestream2_tell(&bc));
if (bytestream2_tell(&bc) >= next_avc) {
/* skip to the start of the next NAL */
bytestream2_skip(&bc, next_avc - bytestream2_tell(&bc));
continue;
}
}
if (pkt->nals_allocated < pkt->nb_nals + 1) {
int new_size = pkt->nals_allocated + 1;
void *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*pkt->nals));
if (!tmp)
return AVERROR(ENOMEM);
pkt->nals = tmp;
memset(pkt->nals + pkt->nals_allocated, 0,
(new_size - pkt->nals_allocated) * sizeof(*pkt->nals));
nal = &pkt->nals[pkt->nb_nals];
nal->skipped_bytes_pos_size = 1024; // initial buffer size
nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
if (!nal->skipped_bytes_pos)
return AVERROR(ENOMEM);
pkt->nals_allocated = new_size;
}
nal = &pkt->nals[pkt->nb_nals];
consumed = ff_h2645_extract_rbsp(bc.buffer, extract_length, &pkt->rbsp, nal, small_padding);
if (consumed < 0)
return consumed;
if (is_nalff && (extract_length != consumed) && extract_length)
av_log(logctx, AV_LOG_DEBUG,
"NALFF: Consumed only %d bytes instead of %d\n",
consumed, extract_length);
pkt->nb_nals++;
bytestream2_skip(&bc, consumed);
/* see commit 3566042a0 */
if (bytestream2_get_bytes_left(&bc) >= 4 &&
bytestream2_peek_be32(&bc) == 0x000001E0)
skip_trailing_zeros = 0;
nal->size_bits = get_bit_length(nal, skip_trailing_zeros);
ret = init_get_bits(&nal->gb, nal->data, nal->size_bits);
if (ret < 0)
return ret;
if (codec_id == AV_CODEC_ID_HEVC)
ret = hevc_parse_nal_header(nal, logctx);
else
ret = h264_parse_nal_header(nal, logctx);
if (ret <= 0 || nal->size <= 0) {
if (ret < 0) {
av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n",
nal->type);
}
pkt->nb_nals--;
}
}
return 0;
}
void ff_h2645_packet_uninit(H2645Packet *pkt)
{
int i;
for (i = 0; i < pkt->nals_allocated; i++) {
av_freep(&pkt->nals[i].skipped_bytes_pos);
}
av_freep(&pkt->nals);
pkt->nals_allocated = 0;
av_freep(&pkt->rbsp.rbsp_buffer);
pkt->rbsp.rbsp_buffer_alloc_size = pkt->rbsp.rbsp_buffer_size = 0;
}
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