[Ffmpeg-devel] [BUG] DV in QuickTime - Aspect Ratio

Baptiste Coudurier baptiste.coudurier
Wed Mar 14 01:36:50 CET 2007


Roman Shaposhnik wrote:
> On Mon, 2007-03-05 at 17:38 -0600, Brian Brice wrote:
>> Hello,
>> I have encoded clips with the DV video codec with having the QuickTime
>> container.  These clips were to have 16:9 aspect ratio.  Having ffmpeg
>> read these clips back in does not maintain the aspect ratio.
>> avctx->sample_aspect_ratio always comes back as {0,1}.  Nothing in the
>> QuickTime demux OR DV decoder sets the aspect ratio.
>   Of course that would be a QT problem because it seems that we have
> a container format not capable of signaling aspect ratio. But then
> again, now that we have SAR generation being part of the DV codec, 
> I have no problem with making SAR recognition being part of the codec
> as well.
>   Anybody thinks its a bad idea ? Anybody thinks that CODECs should
> not set avctx->sample_aspect_ratio ? 

I know mov has specific atoms to declare pixel aspect ratio (pasp), and
clean aperture (clap), my guess is that mov muxer should set them
correctly, I'll fix what needs to be fixed, just supply a dv 16:9
sample, or a way to generate one with ffmpeg.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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