[FFmpeg-devel] [PATCH] lavfi/vf_extractplanes: set input formats to reduce conversions.

[Paul B Mahol]

On 5/7/13, Nicolas George <nicolas.george at normalesup.org> wrote:
> L'octidi 18 floreal, an CCXXI, Paul B Mahol a ecrit :
>> Nope, this is wrong way how to do this, it complicates code for no gain.
>>
>> Why would filter accepts only formats that do not need conversion?
>
> This is caused by two specific properties of this filter:
>
> First, its behaviour is highly dependant on the input format, therefore
> making automatic conversions unwanted.

I do not think such reasoning is valid. There are unscaled conversions and they
are used in such case. Saying that because filter is named this way and not
another is sole reason why it should accept only some formats and deny others
is moot.

>
> Second, it is very picky about the formats it supports (in the RGB case),
> therefore making automatic conversions likely.

I wanted to avoid doing yet another implementation of extracting color
component from packed rgb in libavfilter.

Also I find it better to add code that makes formats conversion in
swscale faster
than adding slow code to single filter to do some limited work.

Also your patch would be first one that adds code that explicitly deny
format conversion
to some filter. (Ignoring noformat special case.)