[FFmpeg-soc] expand filter (alternative to pad syntax)

[vmrsss]

On 17 May 2008, at 00:56, Michael Niedermayer wrote:
>> 	pad=-1:-1:-1:-1:16/9:16
>
> Dont you think that pad=::::16/9:16 is clumsy as well ...

Yes, it is clumsy to count the :, but not as clumsy as the previous  
one, because as a user I have to remember that -1 (rather than say 0  
or -2) is the thing to write if I want to let the filter come up with  
the value for me.

> what about:
>
> pad=aspect
> pad=width:height
> pad=width:height:x:y
> (here the number of arguments seperates the variants)

Good idea, but I think there are more variants (eg specifying a  
padcolor can be used in all the forms, and things like  
pad=-32::::16:16/9:white -- pad with a white box 32 bits horizontally  
and then extend vertically to get a 16/9 frame, all mod16, etc).  
Anyway, at the moment I have modified the code and got the ::: form to  
work robustly enough. Perhaps some better idea will come.

> Direct rendering is a key requirement for av filter, filters not  
> spporting
> it properly are not interresting to me and you will have to find  
> someone
> else to review the patch
>
> That said i dont care if its commited to soc. To ffmpeg-svn it will  
> not be.

Fair enough. I just meant that direct rendering is a problem for  
avfilter as a whole, not of this specific filter.