The PPS may contain a few trailing elements whose presence is only signalled by data remaining after the the mandatory part has been parsed. The current code fails to take into account the rbsp_trailing_bits() when deciding whether to parse these optional elements. Assuming no unnecessary padding bytes are passed to this function, the optional elements are present if either more than 8 extra bits remain or the remaining bits do not form a valid rbsp_trailing_bits() after the mandatory PPS elements have been parsed.
Signed-off-by: Mans Rullgard <m...@mansr.com> --- libavcodec/h264_ps.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/libavcodec/h264_ps.c b/libavcodec/h264_ps.c index 7491807..bb673e9 100644 --- a/libavcodec/h264_ps.c +++ b/libavcodec/h264_ps.c @@ -462,6 +462,7 @@ int ff_h264_decode_picture_parameter_set(H264Context *h, int bit_length){ unsigned int pps_id= get_ue_golomb(&s->gb); PPS *pps; const int qp_bd_offset = 6*(h->sps.bit_depth_luma-8); + int bits_left; if(pps_id >= MAX_PPS_COUNT) { av_log(h->s.avctx, AV_LOG_ERROR, "pps_id (%d) out of range\n", pps_id); @@ -538,7 +539,9 @@ int ff_h264_decode_picture_parameter_set(H264Context *h, int bit_length){ memcpy(pps->scaling_matrix4, h->sps_buffers[pps->sps_id]->scaling_matrix4, sizeof(pps->scaling_matrix4)); memcpy(pps->scaling_matrix8, h->sps_buffers[pps->sps_id]->scaling_matrix8, sizeof(pps->scaling_matrix8)); - if(get_bits_count(&s->gb) < bit_length){ + bits_left = bit_length - get_bits_count(&s->gb); + if (bits_left && (bits_left > 8 || + show_bits(&s->gb, bits_left) != 1 << (bits_left - 1))) { pps->transform_8x8_mode= get_bits1(&s->gb); decode_scaling_matrices(h, h->sps_buffers[pps->sps_id], pps, 0, pps->scaling_matrix4, pps->scaling_matrix8); pps->chroma_qp_index_offset[1]= get_se_golomb(&s->gb); //second_chroma_qp_index_offset -- 1.7.7 _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel