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

[Soft Works]

> -----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?

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

Kind regards,
softworkz