[FFmpeg-devel] [PATCH] Make decoding alpha optional forsomecodecs.

Don Moir donmoir at comcast.net
Wed Sep 18 15:40:28 CEST 2013

----- Original Message ----- 
From: "Robert Krüger" <krueger at lesspain.de>
To: "FFmpeg development discussions and patches" <ffmpeg-devel at ffmpeg.org>
Sent: Wednesday, September 18, 2013 9:18 AM
Subject: Re: [FFmpeg-devel] [PATCH] Make decoding alpha optional forsomecodecs.

> On Wed, Sep 18, 2013 at 2:54 PM, Don Moir <donmoir at comcast.net> wrote:
>>> On Wed, Sep 18, 2013 at 1:33 PM, Kieran Kunhya <kierank at obe.tv> wrote:
>>>> This patch is a good idea for quick previews and the likes.
>> If it's the default behavior, maybe. If it's not the default behavior, you
>> might have to dig up the option that would only work sometimes and probably
>> add more confusion.
> Of course it should not be default behavior and that's what Michael
> suggested and I think that's good because people who know how to use
> it can and others don't need to worry about it. If all I have to do in
> our video player to get a few percent less CPU load for these formats
> is to set an option for a given list of formats (might not even be
> necessary if the codec would simply ignore the flag if it does not
> apply), I would certainly do that.

Yes, originally it just wasn't clear before comments came in and just to be sure.

>>> and basically every video player. E.g. quicktime displays full
>>> transparency in Prores4444 as black and so does FCP. You only see the
>>> alpha if you actually have an overlay. So people building software for
>>> looking at single video clips would probably like it to behave the
>>> same and if that can be achieved with less CPU it definitely has
>>> value.
>> I suspect no measurable CPU decrease on a modern computer and some on older
>> computers. If user has a computer that can barely keep up, well he has
> Just curious, on what do you base the assumption?

I base it on extreme testing. I have an i7 next to me where I ran 15 HD videos at same time and it wasn't even breathing hard.

On my slower machine, yes it might make a difference but probably not by much. If user is watching general video in all shapes and 
sizes on low end computer, his experience can't be that good.

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