[FFmpeg-devel] [PATCH 5/5] libavcodec/jpeg2000dec.c: Remove log2_chroma check in pixel format selection

[Carl Eugen Hoyos]

Am Mo., 22. Juni 2020 um 04:57 Uhr schrieb Gautam Ramakrishnan
<gautamramk at gmail.com>:
>
> On Mon, Jun 22, 2020 at 1:54 AM Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> >
> > Am So., 21. Juni 2020 um 21:11 Uhr schrieb <gautamramk at gmail.com>:
> > >
> > > From: Gautam Ramakrishnan <gautamramk at gmail.com>
> > >
> > > The log2_chroma_wh is derived from the sample separations of the
> > > codestream if the file is a j2k codestream. Not sure if sample
> > > separation is same is subsampling and whether using sample
> > > separation values from the codestream to determine pixel format.
> >
> > What would get fixed by this change?
> >
> The p1_01.j2k image was not getting recognized by the native
> decoder due to this condition.

In any case, this was missing from the commit message.

> It would now get recognized. If this patch is fine,

I wanted to suggest to add the following two lines after
the calls to pix_fmt_guess():
    if (s->avctx->pix_fmt == AV_PIX_FMT_NONE && ncomponents == 1)
        s->avctx->pix_fmt = AV_PIX_FMT_GRAY8;

But p1_01.j2k does not get decoded with the change either here.

> I would preferably remove this check at all places.

I thought the check is needed but if fuzzing does not produce
invalid memory access for you, it may be ok.

Carl Eugen