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

Baptiste Coudurier baptiste.coudurier
Wed Mar 14 11:51:20 CET 2007


herve.flores wrote:
> Le 14 mars 07 ? 01:36, Baptiste Coudurier a ?crit :
>> Hi
>> 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),
> beware of the aperture bit, it's a very stange thing (introduce in QT7
> and not recognize with earlier versions)

Can you please quote the specs ?

>> 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.
> ffmpeg -i input -aspect 16:9 -target pal-dv output.dv

I think bug reported here is about DV in quicktime, not DIF.

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