[Ffmpeg-devel] DAR and SAR FFmpeg option confusion

[Robert Swain]

Roman Shaposhnik wrote:
> On Tue, 2007-03-13 at 09:27 +0000, M?ns Rullg?rd wrote:
>> The problem with DV appears to be that it is outright lying about the
>> aspect ratios. 
> 
>   What is lying in your opinion ? The codec ? The SPEC ? The
> information presented here ?
>        http://www.mir.com/DMG/aspect.html
>   Please be more specific.
> 
>   Also, you say that its just DV, not really -- SVCD for example
> would also have the same problem.
> 
>>  Given two of DAR, SAR and size, the third can be
>> easily calculated.  The numbers you gave are inconsistent.  We can't
>> easily "fix" it as mathematics won't bend very easily.
> 
>    Which numbers and why do you think they are inconsistent ? Once
> again, please go read: http://www.mir.com/DMG/aspect.html and if 
> you find yourself in disagreement with what's written there then we
> can talk about it meaningfully. The numbers Robert and I quoted are
> very consistent with what's written as part of the resource mentioned
> above.

Not to put words in his mouth but I think what M?ns is getting at is that the 
DAR should be 15:11, not 4:3 as they claim. The video stream is 720x480 and not 
704x480. If you have to set a DAR of 4:3 in the stream but the DAR should 
actually be 15:11, this is the lie/hack.

Anything using DV has to be aware of this nuance of the format if it analyses 
the stream, finds a DAR of 4:3 and frame dimensions of 720x480, the only way 
it's going to display the stream as intended is with a workaround for DV.

Rob