Am 23.07.2014 15:49 schrieb "Benoit Fouet" <benoit.fo...@free.fr>:
>
> Try to detect new extradata when parsing frames, and decode it.
> Fixes issue #3787
> ---
> libavcodec/h264_parser.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/libavcodec/h264_parser.c b/libavcodec/h264_parser.c
> index ea0ab98..c8276a7 100644
> --- a/libavcodec/h264_parser.c
> +++ b/libavcodec/h264_parser.c
> @@ -489,6 +489,40 @@ static int h264_parse(AVCodecParserContext *s,
> }
> }
>
> + /* See if this is extradata */
> + if (h->is_avc &&
> + buf_size >= 9 &&
> + buf[0] == 1 &&
> + (buf[4] & 0xFC) == 0xFC &&
> + (buf[5] & 0x1F) &&
> + buf[8] == 0x67) {
> +
> + /* Skip the SPSs */
> + int cnt = buf[5] & 0x1f;
> + const uint8_t *p = buf + 6;
> + while (cnt--) {
> + int nalsize = AV_RB16(p) + 2;
> + if (nalsize > buf_size - (p - buf) || p[2] != 0x67)
> + goto not_extra;
> + p += nalsize;
> + }
> +
> + /* Skip the PPSs */
> + cnt = *p++;
> + if (!cnt)
> + goto not_extra;
> + while (cnt--) {
> + int nalsize = AV_RB16(p) + 2;
> + if (nalsize > buf_size - (p - buf) || p[2] != 0x68)
> + goto not_extra;
> + p += nalsize;
> + }
> +
> + /* Decode (new) extradata */
> + return ff_h264_decode_extradata(h, buf, buf_size);
> + }
> +
> +not_extra:
> parse_nal_units(s, avctx, buf, buf_size);
>
> if (h->sei_cpb_removal_delay >= 0) {
> --
> 2.0.1.442.g7fe6834
>
Having AVC style extradata in the middle of a stream seems like an invalid
file. The stream should only include NALUs, with start code or with size
prefix, but not random extra data.
I'm not liking such a hack, especially in the parser, as the decoder and
parser could even use separate context (parsing is typically done in the
demuxing step)
- Hendrik
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