[FFmpeg-devel] avcodec/qsvenc Question for Intel QSV low latency

Michael Niedermayer michael at niedermayer.cc
Sun Nov 12 18:13:02 EET 2017


On Sun, Nov 12, 2017 at 11:40:57AM +0900, Natsuki Kai wrote:
> Hello guys,
> 
> this is my first posting to ffmpeg-devel, and I believe my mail format is
> correct.
> 
> I'm using ffmpeg for encoding video in real-time, so low encode delay is
> needed.
> Once I call "avcodec_send_frame(avctx, frame)", I'd like to get the encoded
> data from "avcodec_receive_packet(avctx, avpkt)".
> 
> However I cannot do that in ffmpeg and Intel QSV (qsv),
> "avcodec_receive_packet()" returns nothing when I input the first frame to
> qsv encoder by calling "avcodec_send_frame()".
> Of cource, after second frame inputs, qsv encoder returns valid data.
> I'd like to get a valid data from first calling.
> 
> I've tried some cases and as a result, my requirement is satisfied when
> avcodec/qsvenc.c will be fixed like below diff info.
> Then I have a question.
> Why q->async_fifo is set to be q->async_depth "+ 1"?
> Anybody knows?
> 
> --- a/avcodec/qsvenc.c
> +++ b/avcodec/qsvenc.c
> @@ -803,7 +803,7 @@
> 
>      q->param.AsyncDepth = q->async_depth;
> 
> -    q->async_fifo = av_fifo_alloc((1 + q->async_depth) *
> +    q->async_fifo = av_fifo_alloc((q->async_depth) *
>                                    (sizeof(AVPacket) +
> sizeof(mfxSyncPoint*) + sizeof(mfxBitstream*)));
>      if (!q->async_fifo)
>          return AVERROR(ENOMEM);

This looks corrupted by a newline

Applying: avcodec/qsvenc Question for Intel QSV low latency
error: corrupt patch at line 10

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are best at talking, realize last or never when they are wrong.
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