[FFmpeg-devel] [RFC PATCH] libavcodec/libopenjpeg: pix fmt selection change

[Gautam Ramakrishnan]

On Thu, Jun 11, 2020 at 11:42 AM Michael Bradshaw <mjbshaw at gmail.com> wrote:
>
> On Wed, Jun 10, 2020 at 9:35 PM Gautam Ramakrishnan <gautamramk at gmail.com>
> wrote:
>
> > The reference file has 4 components, Whereas all the Bayer formats
> > have 3 components. Are we missing any Bayer pixel format in ffmpeg?
> > Also, any other ideas on what has to be done for the 2 reference files
> > mentioned? If this seems like a good idea, I could go through
> > opj_decompress
> > and try to replicate what it does.
>
>
> I don't think this is a real image. I think it's probably just a synthetic
> image for the purposes of conformance testing. p1_03.j2k and p0_05.j2k (and
> others) are too weird.
>
> I decoded p1_03.j2k's components into different files (opj_decompress -i
> p1_03.j2k -split-pnm -o /tmp/p1_03.pgm) and inspected each one.
> Additionally, I cat'd the raw gray8 pixel values to construct raw yuv420p
> frames. I created 4 raw yuv420p frames using every valid combination
> of p1_03.j2k's four planes. All of them looked like garbage.
>
> That's not too surprising. Each plane has dark near-zero pixel values in
> the sky region. A bright region like the sky should have high pixel values
> for the Y-plane.
>
> I highly suspect this j2k file is synthetic and just tests whether or not a
> decoder can decode the planes, but that doesn't test whether or not they
> can be sensibly displayed (and I'd argue they can't be sensibly displayed).
Got it. In that case we can safely ignore the patch to fix libopenjpeg.
However, p1_03.j2k is one of the 2 files to have ppm marker. How could I
validate a patch to add ppm marker? I need something to cross validate.
Any suggestions for that?
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-- 
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Gautam |