[FFmpeg-devel] FFV1 specification: plane_count prior to version 4

[Michael Niedermayer]

On Sat, May 02, 2015 at 02:41:33AM +0200, Jerome Martinez wrote:
> Le 02/05/2015 01:37, Michael Niedermayer a écrit :
> >plane_count was 2 for gray prior to version 4 [...]
> 
> Got it.
> Maybe I missed something else, but looks like decode_plane() is
> never called with plane_index = 1 if chroma_planes is 0.
> Was it an implementation bug and actually plane_index = 1 is never
> used in the case of gray?
> 
> Additionally, I read this code:
> 
> >         if (fs->transparency)
> >             decode_plane(fs, p->data[3] + ps*x + y*p->linesize[3],
> width, height, p->linesize[3], 2);
> 
> plane_index is 2 for the alpha plane if transparency is 1, in all cases.
> but I understood that for version >= 4, plane_count is 2 if
> grey+alpha, so plane_index = 2 would not be possible.
> 
> shouldn't it be
>         if (fs->transparency)
>             decode_plane(fs, p->data[3] + ps*x + y*p->linesize[3],
> width, height, p->linesize[3], (f->version >= 4 &&
> !f->chroma_planes) ? 1 : 2);

yes, i think so too, please send a patch, note though this isnt
a bug as the case where this matters isnt supported

[..]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In fact, the RIAA has been known to suggest that students drop out
of college or go to community college in order to be able to afford
settlements. -- The RIAA
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <https://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20150502/962e9990/attachment.asc>