[FFmpeg-cvslog] ffmpeg: fix aspect ratio setting

[Baptiste Coudurier]

On 04/05/2011 09:17 AM, Stefano Sabatini wrote:
> On date Tuesday 2011-04-05 09:23:10 -0700, Baptiste Coudurier wrote:
>> On 04/05/2011 07:48 AM, Stefano Sabatini wrote:
>>> ffmpeg | branch: master | Stefano Sabatini <stefano.sabatini-lala at poste.it> | Mon Apr  4 02:15:34 2011 +0200| [d1eb50bb29caad9745631759265f475177df99b9] | committer: Stefano Sabatini
>>>
>>> ffmpeg: fix aspect ratio setting
>>>
>>> This is done by adding a setsar filter at the beginning of the
>>> configured filterchain.
>>>
>>> This implementation is more robust, since does not modify the
>>> filterchain description (which was creating potential syntax errors),
>>> but directly modifies the filterchain structure.
>>>
>>> This also changes the ffmpeg -aspect behavior, as following filters in
>>> the filterchain can change the DAR/SAR set by the inserted setsar
>>> filter.
>>
>> Please don't change -aspect behavior, there is no reason to.
> 
> It was breaking syntax (e.g.: -aspect A -vf "null[out]").
> 
> Another option could be to add an aspect filter at the end of the
> filterchain, thus annulling the effects of the previous filters in the
> filterchain.
> 
> That said, I don't see a sane way to make -vf and -aspect convive when
> filtering is enabled, that is i'd tend to say to the user to just use
> -vf when she wants to change the final aspect (and keep -aspect for
> -vcodec copy).

Having 2 options is confusing for the user.

I think the correct solution is to avoid adding filters when -aspect is
specified on the commandline, and check frame_aspect_ratio directly.
My first patch did this. It's easy to distinguish between -aspect
specified or not.

If it was, override the output aspect ratio no matter what (at the end
of configure_filters)

-- 
Baptiste COUDURIER
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