[FFmpeg-devel] [PATCH 5/5] avformat/av1dec: Flush BSF upon seeking

[James Almer]

On 8/22/2021 8:29 AM, Andreas Rheinhardt wrote:
> The av1_merge_frame BSF outputs its cached data when it sees the
> beginning of a new frame, i.e. when it sees a temporal delimiter OBU.
> Therefore it typically has a temporal delimiter OBU cached after
> outputting a packet.
> 
> This implies that the OBU demuxer must flush its BSF upon seeking
> because otherwise the first frame returned after a seek consists
> of an old temporal delimiter OBU only.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
> The AV1 Annex B demuxer also has two issues: It records the wrong
> positions (it is off due to the annex b packetization) and it needs to
> flush the bsf, too. Will look into it.
> 
>   libavformat/av1dec.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/libavformat/av1dec.c b/libavformat/av1dec.c
> index d5d4548d8b..88a3c325e4 100644
> --- a/libavformat/av1dec.c
> +++ b/libavformat/av1dec.c
> @@ -390,6 +390,10 @@ static int obu_read_packet(AVFormatContext *s, AVPacket *pkt)
>       AV1DemuxContext *const c = s->priv_data;
>       int ret;
>   
> +    if (s->io_repositioned) {
> +        av_bsf_flush(c->bsf);
> +        s->io_repositioned = 0;
> +    }
>       while (1) {
>           ret = obu_get_packet(s, pkt);
>           /* In case of AVERROR_EOF we need to flush the BSF. Conveniently

LGTM.