[FFmpeg-devel] [PATCH 2/2] avcodec/decode: don't discard the buffered packet if the underlying bsf can't take it

[Anton Khirnov]

Quoting James Almer (2023-07-12 13:40:25)
> On 7/12/2023 6:08 AM, Anton Khirnov wrote:
> > Quoting James Almer (2023-07-12 04:06:44)
> >> Signed-off-by: James Almer <jamrial at gmail.com>
> >> ---
> >>   libavcodec/decode.c | 3 ++-
> >>   1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> >> index 239ad70b41..cd49cca7c2 100644
> >> --- a/libavcodec/decode.c
> >> +++ b/libavcodec/decode.c
> >> @@ -242,7 +242,8 @@ int ff_decode_get_packet(AVCodecContext *avctx, AVPacket *pkt)
> >>               (!AVPACKET_IS_EMPTY(avci->buffer_pkt) || dc->draining_started)) {
> >>               ret = av_bsf_send_packet(avci->bsf, avci->buffer_pkt);
> >>               if (ret < 0) {
> >> -                av_packet_unref(avci->buffer_pkt);
> >> +                if (ret != AVERROR(EAGAIN))
> >> +                    av_packet_unref(avci->buffer_pkt);
> > 
> > It seems very wrong for ff_decode_get_packet() to return EAGAIN when
> > we have a buffered packet.
> 
> The idea is preventing dropping a packet in the hypothetical case the 
> bsf can't take it. Is this scenario possible, or is the call to 
> av_bsf_receive_packet() within the loop ensuring it wont?

This block can only be entered if decode_get_packet() returned EAGAIN,
which should always mean that the bsf is empty.

-- 
Anton Khirnov