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h264: improve parsing of broken AVC SPS 

Parsing the entire NAL as SPS fixes decoding of some AVC bitstreams
with broken escaping. Since the size of the NAL unit is known and
checked against the buffer end we can parse it entirely without buffer
overreads.

Fixes playback of
http://streams.videolan.org/streams/mp4/Mr_MrsSmith-h264_aac.mp4

Signed-off-by: Janne Grunau <janne-libav@jannau.net>
This commit is contained in:
Michael Niedermayer 2011-10-01 17:41:28 +02:00 committed by Janne Grunau
parent bd3e07c82a
commit 3aa661ec56
2 changed files with 12 additions and 2 deletions
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9
libavcodec/h264.c
View File

@ -3925,7 +3925,14 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size){
break;
case NAL_SPS:
init_get_bits(&s->gb, ptr, bit_length);
ff_h264_decode_seq_parameter_set(h);
if (ff_h264_decode_seq_parameter_set(h) < 0 &&
h->is_avc && (nalsize != consumed) && nalsize) {
av_log(h->s.avctx, AV_LOG_DEBUG, "SPS decoding failure, "
"try parsing the coomplete NAL\n");
init_get_bits(&s->gb, buf + buf_index + 1 - consumed,
8 * (nalsize - 1));
ff_h264_decode_seq_parameter_set(h);
}
if (s->flags& CODEC_FLAG_LOW_DELAY ||
(h->sps.bitstream_restriction_flag && !h->sps.num_reorder_frames))

5
libavcodec/h264_ps.c
View File

@ -228,7 +228,6 @@ static inline int decode_vui_parameters(H264Context *h, SPS *sps){
get_ue_golomb(&s->gb); /*max_dec_frame_buffering*/
if (get_bits_left(&s->gb) < 0) {
av_log(h->s.avctx, AV_LOG_ERROR, "Overread VUI by %d bits\n", -get_bits_left(&s->gb));
sps->num_reorder_frames=0;
sps->bitstream_restriction_flag= 0;
}
@ -238,6 +237,10 @@ static inline int decode_vui_parameters(H264Context *h, SPS *sps){
return -1;
}
}
if (get_bits_left(&s->gb) < 0) {
av_log(h->s.avctx, AV_LOG_ERROR, "Overread VUI by %d bits\n", -get_bits_left(&s->gb));
return AVERROR_INVALIDDATA;
}
return 0;
}