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

[Måns Rullgård]

Roman Shaposhnick <rvs at sun.com> writes:

> On Wed, 2007-03-14 at 16:51 -0500, Brian Brice wrote:
>> > 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...
>> 
>> I'm not quite sure if all of this is needed for QuickTime? 
>
>   My assumption all along has been that it is usually container's
> job to store things like SAR, DAR, etc. But since DV is both
> a container and a codec format I have nothing against moving 
> SAR initialization to libavcodec. Unless somebody tells me
> its a stupid idea.

Many codecs indicate SAR or DAR in the stream headers, whereas only a
few containers do so.

>> Using the command that herve posted would create a video that the
>> QuickTime player recognizes as 16:9, but ffmpeg reading does not.
>
>   Right. And that's because QuickTime gives precedence to the DV
> metadata and not the container, ffmpeg is the other way around.
> I'm not really sure which way I prefer.

When the container does indicate aspect ratio, I've found that a large
proportion of files in the wild have different values in container and
elementary stream, neither being correct more frequently.

-- 
M?ns Rullg?rd
mans at mansr.com