[FFmpeg-soc] avfilter: what data ought to be available for configuration?

[Michael Niedermayer]

On Thu, May 22, 2008 at 02:45:45PM +0100, vmrsss wrote:
> 
> On 17 May 2008, at 22:17, Michael Niedermayer wrote:
> 
> >>> The problem is that the way the pixel_aspect is handled in lavf,  
> >>> it is
> >>> a field of each one of the pictures (I wonder what is the use of  
> >>> that,
> >>> if you can't change dimensions on the fly, why would you need to
> >>> change the pixel aspect ratio?).
> >
> > Well, maybe we one day will fully support changing dimensions on the  
> > fly.
> > Adding a sample_aspect_ratio to AVCodecContext would surely be  
> > possible
> > if this solves the problem.
> 
> 
> Unless I am mistaken, there is already a sample_aspect_ratio in  
> AVCodecContext. What am I missing?

That iam stupid ...


> 
> My question is whether we need to add a sample_aspect_ratio field to  
> AVFilterLink and make it available at filter configuration-time. More  
> generally: what codec parameters are likely to be needed in order to  
> **configure** (not run) a filter chain? Width, height, PIX_FMT, SAR  
> for sure (any others? fps? interlaced flags?).

sar can certainly be added. Others are a seperate question and not related
to sar.

Also it should be clear that there may be filters which could
support changing sar/width/height at "runtime", the implementation should
not throw any stones in the way of such filters.

For example a filter chain starting with a scale filter could easily
support changing width height at the scale input and then "normalize"
it to a sigle width/height at its output.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No snowflake in an avalanche ever feels responsible. -- Voltaire
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