[FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust incorrect error output

[Wang, Fei W]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Soft
> Works
> Sent: Friday, August 27, 2021 1:25 PM
> To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust incorrect error
> output
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Wang, Fei W
> > Sent: Friday, 27 August 2021 06:39
> > To: FFmpeg development discussions and patches <ffmpeg-
> > devel at ffmpeg.org>
> > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust incorrect
> > error output
> >
> >
> >
> > > -----Original Message-----
> > > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Soft
> > > Works
> > > Sent: Friday, August 27, 2021 12:18 PM
> > > To: FFmpeg development discussions and patches <ffmpeg-
> > devel at ffmpeg.org>
> > > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust
> > incorrect error
> > > output
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > > > Wang, Fei W
> > > > Sent: Friday, 27 August 2021 05:05
> > > > To: FFmpeg development discussions and patches <ffmpeg-
> > > > devel at ffmpeg.org>
> > > > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust
> > incorrect
> > > > error output
> > > >
> > > > > -----Original Message-----
> > > > > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf
> > Of
> > > > Soft
> > > > > Works
> > > > > Sent: Thursday, August 26, 2021 5:12 AM
> > > > > To: FFmpeg development discussions and patches <ffmpeg-
> > > > devel at ffmpeg.org>
> > > > > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust
> > > > incorrect error
> > > > > output
> > > > >
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On
> > Behalf Of
> > > > > > Wang, Fei W
> > > > > > Sent: Tuesday, 24 August 2021 07:32
> > > > > > To: ffmpeg-devel at ffmpeg.org
> > > > > > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec: Adjust
> > > > incorrect
> > > > > > error output
> > > > > >
> > > > > > On Tue, 2021-08-24 at 02:45 +0000, Soft Works wrote:
> > > > > > > > -----Original Message-----
> > > > > > > > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On
> > > > Behalf Of
> > > > > > > > Ronald S. Bultje
> > > > > > > > Sent: Tuesday, 24 August 2021 04:34
> > > > > > > > To: FFmpeg development discussions and patches <ffmpeg-
> > > > > > > > devel at ffmpeg.org>
> > > > > > > > Subject: Re: [FFmpeg-devel] [PATCH] avcodec/av1dec:
> > Adjust
> > > > > > > > incorrect error output
> > > > > > > >
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > On Mon, Aug 23, 2021 at 9:39 PM Soft Works
> > > > > > <softworkz at hotmail.com>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > The current message "Your platform doesn't suppport
> > > > hardware
> > > > > > > > > accelerated AV1 decoding." is inaccurate and
> > misleading.
> > > > When a
> > > > > > > > > user doesn't specify a hwcaccel, this doesn't tell
> > anything
> > > > > > > > > about what is actually supported on that platform.
> > > > > > > > >
> > > > > > > > > Signed-off-by: softworkz <softworkz at hotmail.com>
> > > > > > > > > ---
> > > > > > > > >  libavcodec/av1dec.c | 4 ++--
> > > > > > > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > > > > > >
> > > > > > > > > diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
> > > > index
> > > > > > > > > a75d6744d3..8dfcd26cb6 100644
> > > > > > > > > --- a/libavcodec/av1dec.c
> > > > > > > > > +++ b/libavcodec/av1dec.c
> > > > > > > > > @@ -462,8 +462,8 @@ static int
> > > > get_pixel_format(AVCodecContext
> > > > > > > >
> > > > > > > > *avctx)
> > > > > > > > >       * 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");
> > > > > > > > > +        av_log(avctx, AV_LOG_ERROR, "AV1 decoding
> > requires
> > > > a
> > > > > > hw
> > > > > > > > > acceleration"
> > > > > > > > > +               " to be specified.\n");
> > > > > > > > >
> > > > > > > >
> > > > > > > > This is misleading.
> > > > > > > >
> > > > > > > > This error message (for me) happens when I accidentally
> > > > compile
> > > > > > > > FFmpeg without aom/dav1d support, and try to play AV1
> > > > content.
> > > > > > >
> > > > > > > It also happens to me when I specify:
> > > > > > >
> > > > > > > ffmpeg -c:v av1 -i INPUT OUTPUT
> > > > > > >
> > > > > > > (e.g. like when I'd have forgotten to specify the hwaccel)
> > > > > > >
> > > > > > > > AV1 decoding
> > > > > > > > does
> > > > > > > > not require hw decoding - it simply requires an external
> > > > library.
> > > > > > > >
> > > > > > > > Will the hwaccel be autodetected when AV1 hw decoding is
> > > > > > supported
> > > > > > > > by
> > > > > > > > the
> > > > > > > > platform?
> > > > > > >
> > > > > > > No.
> > > > > > >
> > > > > > > How about this: "The AV1 decoder requires a hw acceleration
> > to
> > > > be
> > > > > > > specified." ?
> > > > > >
> > > > > > This will bring new misleading if user specify the hw
> > > > acceleration but
> > > > > > the hardware itself doesn't support av1 dec.
> > > > >
> > > > > Such situations may happen, but this is not subject of this
> > patch.
> > > > > This patch is about the error that is printed when no hw
> > > > acceleration has been
> > > > > specified.
> > > >
> > > > Yes, I understand your purpose. But here avctx->hwaccel==NULL
> > does not
> > > > stands for hw acceleration has not been specified in a hundred
> > > > percent. If specificed hw acceleration init fail in
> > > > ff_thread_get_format which is just 1 line above your modify, then
> > > > avctx->hwaccel will be NULL too. And even the hw init fail,
> > return
> > > > value of ff_thread_get_format may 0 with some error log printed.
> > For
> > > > example run the cmd on Skylake:
> > > > $ ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -v
> > verbose
> > > > -i av1.ivf -pix_fmt yuv420p -vsync passthrough -f null -
> > > >
> > > > Output log will be:
> > > > [av1 @ 0x556613499fc0] No support for codec av1 profile 0.
> > > > [av1 @ 0x556613499fc0] Failed setup for format vaapi: hwaccel
> > > > initialisation returned error.
> > > > [av1 @ 0x556613499fc0] Your platform doesn't suppport hardware
> > > > accelerated AV1 decoding.
> > >
> > > Ok, now let's take your output and replace the message with the
> > proposed one:
> > >
> > >
> > > [av1 @ 0x556613499fc0] No support for codec av1 profile 0.
> > > [av1 @ 0x556613499fc0] Failed setup for format vaapi: hwaccel
> > initialisation
> > > returned error.
> > > [av1 @ 0x556613499fc0] The AV1 decoder requires a hw acceleration
> > to be
> > > specified.
> >
> > But I did specific a hw acceleration in my cmline. This message gives
> > me a sense that I didn't.
> 
> Hi Fei,
> 
> You see two error messages indicating that the hwaccel that you have specified
> couldn't be initialized and doesn't support codec av1.
> And after that, the third message will still make you think that you didn't specify
> a hwaccel?

Yes, that's what I mentioned "new misleading."

> 
> If you want to work this out more perfectly though, go ahead and submit an
> improved patch, I'm fine with it :-)

Thanks Softworkz! I will submit a new one by checking avctx-> hw_device_ctx. :)

> 
> Kind regards,
> softworkz
> 
> 
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