[FFmpeg-devel] [PATCH] libavfilter-soc: implement pad filter

Stefano Sabatini stefano.sabatini-lala
Tue Apr 28 22:03:53 CEST 2009

On date Tuesday 2009-04-28 11:33:32 +0100, vmrsss encoded:
> Hi Stefano,
> 	I am glad you resurrected this, well done. Apart lacking RGB support,  
> the way I remember it is that the filter worked well, but Michael wanted 
> memcpy removed in favour or direct rendering and I did not know how to 
> achieve that. (Also, at the time some necessary info about the input 
> stream was missing from the AVFilter structures, but this might not be 
> the case now.)
> Regards,
> -vmrsss
> PS.	Besides the padcolor option (yes, it would be nice to extract some  
> of the code I had written to a colourutil.[hc]), I still think that some 
> of the other options I had originally considered add flexibility and 
> although not vital may still be useful, in particular:
> 	w / h = - N or h=-N to enlarge by N pixels

This is already implemented.

> 	a = r to require expansion to fit a particular aspect ratio (rather  
> than size)
> for instance
>  	pad=w=-32:a=16/9 (enlarge width by 32 pixel and then height
> 		as required to yield overall aspect ratio 16/9).
>  	pad=w=-32:a=-1 (enlarge width by 32 pixel and then height
> 		as required to keep original aspect ratio).
> I suppose the first form you could write as "pad=w=-32:h=w*9/16", which 
> is very pretty, how about the second?


(Now that I think at it it would be a lot less confusing the form:

But unfortunately expressions are evaluated in this order:
W H x y

so you can't do for example:

since when evaluating the expression for W, the value for H has not
still been defined.

I have an idea to fix this problem, but it would require a deep rework
of the options system.

FFmpeg = Fundamental and Foolish Mean Plastic Elitist Geek

More information about the ffmpeg-devel mailing list