[FFmpeg-devel] [PATCH] Fix linesize computation for NV formats

Ramiro Polla ramiro.polla
Fri Nov 20 12:56:32 CET 2009

On Thu, Nov 19, 2009 at 10:54 PM, Ramiro Polla <ramiro.polla at gmail.com> wrote:
> On Thu, Nov 19, 2009 at 10:38 PM, Stefano Sabatini
> <stefano.sabatini-lala at poste.it> wrote:
>> On date Thursday 2009-11-19 17:51:30 +0100, Michael Niedermayer encoded:
>>> On Thu, Nov 19, 2009 at 01:37:03AM +0100, Stefano Sabatini wrote:
>> [...]
>>> > So basically all the code affected by the change is indeed code which
>>> > is never used, my patch simply makes the linesize params semantics for
>>> > NV formats consistent with that of all the other formats (thus
>>> > simplifying the code if we choose to use pixdesc for ff_fill_XXX).
>>> if no code uses NV12 it should be removed (i dont belive this though)
>>> if any code uses NV12 your patch will break it.
>> ffmpeg doesn't support NV12 as input, but can convert to NV12 /
>> NV21. So we can create a stream with pix_fmt nv12 but there is no mean
>> to visually test it (e.g. with ffplay) or convert it back to a stream
>> which is playable by ffmpeg, but maybe someone can suggest some way to
>> display such a format e.g. with mplayer or vlc.
>> Also I wonder how hard would be to add it as an input format in lsws.
> I have a device with a hardware decoder to nv12 that also displays in
> nv12 at work. I might take a look tomorrow if I manage to find some
> time...

One more change was needed to get raw nv12 output properly. With
attached patch I can
./ffmpeg_g -i input.avi -s 1280x720 -pix_fmt nv12 -f rawvideo -y output.nv12
and then feed output.nv12 to the display frame by frame.

I haven't worked on nv12 support as input to swscale yet. I'll do it
either this afternoon or in two weeks =)

Ramiro Polla
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