[FFmpeg-devel] [PATCH] Make decoding alpha optional for some codecs.

[Don Moir]

----- Original Message ----- 
From: "compn" <tempn at twmi.rr.com>
To: <ffmpeg-devel at ffmpeg.org>
Sent: Thursday, September 19, 2013 6:26 PM
Subject: Re: [FFmpeg-devel] [PATCH] Make decoding alpha optional for some codecs.


> On Thu, 19 Sep 2013 18:05:21 -0400, Don Moir wrote:
>>You could get lucky and some might look ok, but then alpha can give a smooth anti-aliasing effect and that would be lost. So 
>>effort
>>is add clutter to save some CPU cycles at the possible expense of a bad display.
>
> since ffplay doesnt handle alpha now, do your videos look bad in ffplay?
> i mean, not decoding alpha vs decoding alpha, does it make any
> difference when you dont display alpha anyways?

I pretty much don't use ffplay for anything. In my own app, alpha makes a great deal of difference, used as overlays and even when 
video is over black, the smoothness with alpha is very apparent. It's like take a alpha png and remove the alpha. Looks bad. stair 
stepped

When video is scaled it is even more apparent.

If video was not intended to use alpha for effect, then it would not have been encoded with alpha.

Adding an option that probably most will not even know about, to save some CPU cycles in some possible rare cases, to produce 
possible low quality display, just does not add up to me.