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

[Wang, Fei W]

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.

Or like "The AV1 decoder requires a hw acceleration to be specified
or specified hw doesn't support av1 decoding." seems better.

Fei
Thanks

> 
> softworkz
> 
> 
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