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

[herve.flores]

Le 14 mars 07 ? 11:51, Baptiste Coudurier a ?crit :

> Hi
>
> 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 ?

I just have that (not very interesting because I note strange  
behaviors, depends of the origin of the source, its mask layer, its  
display size, etc)
<http://developer.apple.com/documentation/QuickTime/Conceptual/ 
QT7-1_Update_Guide/Content/2NewFeaturesChangesa.html>


>>> 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.

oups!
then a second pass:
ffmpeg -i output.dv -vcodec copy -aspect 16:9 -an output.dv.mov

=> display in QTPlayer : 720*576px

QT's infos:
     QTMovieApertureModeAttribute = clas;
     QTMovieHasApertureModeDimensionsAttribute = 0;

if you set aperture mode to "clean"
and mode dimensions to "1"
then your .mov will be display as 16:9 with QTplayer > v7

PS: the output (.mov) from ffmpeg is "simple", the aperture bit  
"clean" does its job (=display an anamorphous file in square mode)
but with files generated by other softs (iMovie for example, which  
generate a very complicated .mov), it doesn't work every time :-(
so I don't trust the aperture mode...

bye

Herv?