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

[Xiang, Haihao]

On Fri, 2020-09-25 at 06:10 +0000, Wang, Fei W wrote:
> > -----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?


Since commit e46f34e8 was merged, I also saw the same error message when I
tested my QSV av1 patch (
http://ffmpeg.org/pipermail/ffmpeg-devel/2020-September/270234.html) however the
command worked well for me.

[av1 @ 0x55b1604c42d0] Your platform doesn't suppport hardware accelerated AV1
decoding.
[av1 @ 0x55b1604c42d0] Failed to get pixel format.
[av1 @ 0x55b1604c42d0] video_get_buffer: image parameters invalid
[av1 @ 0x55b1604c42d0] get_buffer() failed
[av1 @ 0x55b1604c42d0] thread_get_buffer() failed
[av1 @ 0x55b1604c42d0] Failed to allocate space for current frame.
[av1 @ 0x55b1604c42d0] Get current frame error

I agree with Fei that the user will be confused with this error message.

Thanks
Haihao


> 
> Fei
> Thanks
> 
> > 
> > 
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