[FFmpeg-devel] [PATCH] avcodec/av1dec: check avctx->hwaccel when hwaccel pix_fmt selected

[Wang, Fei W]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Wang,
> Fei W
> Sent: Tuesday, September 22, 2020 11:22 AM
> To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: check avctx->hwaccel
> when hwaccel pix_fmt selected
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > James Almer
> > Sent: Friday, September 18, 2020 8:57 PM
> > To: ffmpeg-devel at ffmpeg.org
> > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: check
> > avctx->hwaccel when hwaccel pix_fmt selected
> >
> > On 9/18/2020 2:40 AM, Wang, Fei W wrote:
> > >
> > >
> > >> -----Original Message-----
> > >> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > >> Hendrik Leppkes
> > >> Sent: Thursday, September 17, 2020 5:21 PM
> > >> To: FFmpeg development discussions and patches
> > >> <ffmpeg-devel at ffmpeg.org>
> > >> Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: check
> > >> avctx->hwaccel when hwaccel pix_fmt selected
> > >>
> > >> On Thu, Sep 17, 2020 at 10:38 AM Fei Wang <fei.w.wang at intel.com>
> wrote:
> > >>>
> > >>> Pix fmt with hwaccel flag may not be chosen in format probing, in
> > >>> this case avctx->hwaccel will not be inited.
> > >>>
> > >>> Signed-off-by: Fei Wang <fei.w.wang at intel.com>
> > >>> ---
> > >>>  libavcodec/av1dec.c | 12 ++++++++----
> > >>>  1 file changed, 8 insertions(+), 4 deletions(-)
> > >>>
> > >>> diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c index
> > >>> 0bb04a3e44..cdcc618013 100644
> > >>> --- a/libavcodec/av1dec.c
> > >>> +++ b/libavcodec/av1dec.c
> > >>> @@ -251,6 +251,7 @@ static int get_pixel_format(AVCodecContext
> > >>> *avctx) {
> > >>>      AV1DecContext *s = avctx->priv_data;
> > >>>      const AV1RawSequenceHeader *seq = s->raw_seq;
> > >>> +    const AVPixFmtDescriptor *desc;
> > >>>      uint8_t bit_depth;
> > >>>      int ret;
> > >>>      enum AVPixelFormat pix_fmt = AV_PIX_FMT_NONE; @@ -327,10
> > >>> +328,13 @@ static int get_pixel_format(AVCodecContext *avctx)
> > >>>       * Since now the av1 decoder doesn't support native decode, if it will be
> > >>>       * implemented in the future, need remove this check.
> > >>>       */
> > >>> -    if (!avctx->hwaccel) {
> > >>> -        av_log(avctx, AV_LOG_ERROR, "Your platform doesn't suppport"
> > >>> -               " hardware accelerated AV1 decoding.\n");
> > >>> -        return AVERROR(ENOSYS);
> > >>> +    desc = av_pix_fmt_desc_get(ret);
> > >>> +    if (desc && (desc->flags & AV_PIX_FMT_FLAG_HWACCEL)) {
> > >>> +        if (!avctx->hwaccel) {
> > >>> +            av_log(avctx, AV_LOG_ERROR, "Your platform doesn't suppport"
> > >>> +                   " hardware accelerated AV1 decoding.\n");
> > >>> +            return AVERROR(ENOSYS);
> > >>> +        }
> > >>>      }
> > >>>
> > >>
> > >> Isn't it supposed to quit here, because we do not have software decoding?
> > >
> > > Since now av1 decoder allow probe, that will try to decode first
> > > frame to find stream info in open_file stage. While the hwaccel will not be
> inited.
> > > If without change here, the error log will be print out but later
> > > during transcode stage, it can gives out the correct output.
> >
> > If you let it choose a software pix_fmt, it will think the decoder can
> > actually output something, which is not true.
> 
> It's better not let ff_thread_get_format choose a software pix fmt here, but for
> VAAPI the avctx->hw_device_ctx hasn't been created in probing so that hwaccel
> can not be inited and hwaccel pix fmt will not be chosen(same mechanism with
> other codecs). And then next available pix fmt in input array will be considered.
> 
> > Probing works fine even if it fails at this point. It will have set
> > enough AVCodecContext fields to allow things like remuxing, hence the
> > relevant fate tests succeeding as is.
> 
> Yes, probing allows fail here. How about to keep the original check(!avctx-
> >hwaccel), and change log context as like "Hardware context not created or
> your platform doesn't support hardware accelerated AV1 decoding" and change
> log level to WARNING ? It's really confused if error log printed but decode works
> correctly.

Kindly ping @James Almer, any comments to change log context and level here?

Fei
Thanks

> 
> 
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