[FFmpeg-devel] libavcodec/webp : fix return code check in lossy decoding

Martin Vignali martin.vignali at gmail.com
Sat Jul 9 18:37:43 EEST 2016


2016-07-09 12:18 GMT+02:00 Michael Niedermayer <michael at niedermayer.cc>:

> On Sat, Jul 09, 2016 at 11:53:04AM +0200, Hendrik Leppkes wrote:
> > On Sat, Jul 9, 2016 at 11:13 AM, Michael Niedermayer
> > <michael at niedermayer.cc> wrote:
> > > On Sun, Jun 26, 2016 at 10:45:33PM +0200, Martin Vignali wrote:
> > >> Hello,
> > >>
> > >> in attach patch to fix ret code check in webp lossy decoding (when
> files
> > >> have alpha)
> > >>
> > >> before this patch, if an error occured during rgb decoding
> > >> the return code was ignored. And a useless ret test was made
> > >> after alpha decoding.
> > >>
> > >> after this patch, the return code of rgb is test before
> > >> trying to decode alpha.
> > >>
> > >>
> > >> Comments welcome
> > >>
> > >> Martin
> > >> Jokyo Images
> > >
> > >>  webp.c |    4 ++--
> > >>  1 file changed, 2 insertions(+), 2 deletions(-)
> > >> 494399734be14a906e03a1b976dbca27c442cdac
> 0001-libavcodec-webp-fix-return-code-check-in-lossy-decod.patch
> > >> From 4b7a1b3c03ec1a9062d3100d79668d905f6226fe Mon Sep 17 00:00:00 2001
> > >> From: Martin Vignali <martin.vignali at gmail.com>
> > >> Date: Sun, 26 Jun 2016 22:36:23 +0200
> > >> Subject: [PATCH] libavcodec/webp : fix return code check in lossy
> decoding
> > >>
> > >> before this patch, if an error occured during rgb decoding
> > >> the return code was ignored. And an useless ret test was made
> > >> after alpha decoding.
> > >>
> > >> after this patch, the return code of rgb is test before
> > >> trying to decode alpha.
> > >
> > > should not both be attempted to be decoded and in case both fail an
> > > error be returned?
> > >
> > > One could be correctly decoded and that should not be discarded
> > > but maybe iam missing something
> > >
> >
> > Decoding the alpha plane when the RGB plane failed seems rather
> > useless, doesn't it.
>
> I dont know
> to me having an alpha plane seems better than having nothing
>
> With slices we generally also return what we can even if its just
> one macroblock we could decode
> also with videos and slices previous frames would be used to fill in
> missing areas ...
>

In attach a new patch.
for rgba lossy file :
if rgb decoding failed, an error is log, but alpha is decode
if alpha decoding failed, an error is log
if both failed, return invalid data.

Comments welcome

Martin
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