Re: [FFmpeg-devel] [PATCH] avformat/mov: Add support for still image AVIF parsing

[Vignesh Venkatasubramanian <vigneshv-at-google.com@ffmpeg.org>]

On Thu, Apr 21, 2022 at 9:16 AM Vignesh Venkatasubramanian
<vigneshv@google.com> wrote:
>
> On Thu, Apr 21, 2022 at 2:08 AM Gyan Doshi <ffmpeg@gyani.pro> wrote:
> >
> >
> >
> > On 2022-04-20 09:54 am, Gyan Doshi wrote:
> > >
> > >
> > > On 2022-04-20 02:49 am, Paul B Mahol wrote:
> > >> On Tue, Apr 19, 2022 at 10:57 PM Vignesh Venkatasubramanian <
> > >> vigneshv-at-google.com@ffmpeg.org> wrote:
> > >>
> > >>> Add support for parsing AVIF still images. This patches supports
> > >>> AVIF still images that have exactly 1 item (i.e.) no alpha channel.
> > >>> Essentially, we will have to parse the "iloc" box and populate
> > >>> the mov index.
> > >>>
> > >>> With this patch, we can decode still AVIF images like so:
> > >>> ffmpeg -i image.avif image.png
> > >>>
> > >>> Partially fixes trac ticket #7621
> > >>>
> > >> LGTM
> > >
> > > Will push tomorrow if no one else has.
> >
> > Can you provide a sample AVIF image and command that this patch allows
> > decoding of?
> >
> > I tried a couple of samples from Netflix[1] and MS[2] and none worked,
> > even with forcing MOV demuxer ("moov atom not found" or "error reading
> > header").
>
> Thanks for verifying. The test files you tried are invalid/not
> supported by this patch. Please see the explanation below.
>
> >
> > [1]: http://download.opencontent.netflix.com/?prefix=AV1/Chimera/AVIF/
>
> These files are not valid AVIF since they don't have the major brand
> set to "mif1" and not "avif". They are also missing a few other
> mandatory boxes. libavif (the reference AVIF library) also is not able
> to parse these files. These files were likely made when the AVIF
> specification was not yet finalized.
>
> $ ./avifdec --info Chimera-AV1-8bit-1280x720-3363kbps-100.avif
> ERROR: Failed to decode image: BMFF parsing failed
> Diagnostics:
>  * [Strict] Item ID 1 of type 'av01' is missing mandatory pixi property
>
> > [2]:
> > https://github.com/AOMediaCodec/av1-avif/tree/master/testFiles/Microsoft
> >
>
> These files have EXIF metadata and will contain more than one item
> entry in the iloc box. This patch does not support that (however, i
> have a follow-up patch to fix this). The files in this directory
> return AVERROR_PATCHWELCOME as intended.
>

The follow-up patch for supporting the files in the "Microsoft"
subdirectory is here:
http://ffmpeg.org/pipermail/ffmpeg-devel/2022-April/295647.html

> For a set of working AVIF files that are supported by this patch you
> can try the files under "Link-U" and "Netflix" subdirectories of this repo:
>
> https://github.com/AOMediaCodec/av1-avif/tree/master/testFiles/Link-U
>
> https://github.com/AOMediaCodec/av1-avif/tree/master/testFiles/Netflix/avif
>
> The command is as mentioned in the commit message:
> ./ffmpeg -i <avif file> output.png
>
> Please let me know if you have more questions. Thank you!
>
>
> > Regards,
> > Gyan
> >
> >
> > _______________________________________________
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> >
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>
>
>
> --
> Vignesh



-- 
Vignesh
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