[FFmpeg-devel] [PATCH] grayalpha pixfmt + support in pngdec

Baptiste Coudurier baptiste.coudurier
Thu Jun 3 02:37:36 CEST 2010

On 04/18/2010 03:57 PM, Michael Niedermayer wrote:
> On Sun, Apr 18, 2010 at 09:36:22PM +0200, Stefano Sabatini wrote:
>> On date Tuesday 2010-04-13 12:21:47 +0200, Michael Niedermayer encoded:
>>> On Tue, Apr 13, 2010 at 10:34:48AM +0200, Andreas ?man wrote:
>>>> Kostya wrote:
>>>>> On Tue, Apr 13, 2010 at 09:33:51AM +0200, Andreas ?man wrote:
>>>>>> Michael Niedermayer wrote:
>>>>>>> On Mon, Apr 12, 2010 at 09:40:03PM +0200, Andreas ?man wrote:
>>>>>>>> Michael Niedermayer wrote:
>>>>>>>>> On Mon, Apr 12, 2010 at 10:43:02AM +0200, Andreas ?man wrote:
>>>>>>>>>> Hi
>>>>>>>>>> +    [PIX_FMT_GRAYALPHA] = {
>>>>>>>>>> +        .name = "grayalpha",
>>>>>>>>> where does the name grayalpha come from?
>>>>>>>> I just didn't come up with anything better.
>>>>>>>> Ideas are most welcome.
>>>>>>> something that is consistent with existing formats would
>>>>>>> be better also what is it calld in the png docs?
>>>>>> PNG docs seems to call it "Grayscale with alpha" or "ya".
>>>>>> Perhaps "ya" would be a good name then?
>>>>> Nej, it obviously stands for "Y(aka luma) + A(alpha)"
>>>>> i.e. not so good acronym.
>>>> Kostya suggested "Y400A" on IRC.
>> I'm not very happy with this name, "4XX" notation only makes sense
>> when we have three components, in this case I would have preferred
>> something of the kind GRAY8ALPHA8 or GRAYALPHA8 (consistent with
>> GRAY8), even YA was not that bad.
> GRAY*ALPHA* is inconsistent with the existing naming and gray8 is quite
> alone and the exception, not a good example to copy.
>> Not that I consider this a big issue, we will eventually fix the names
>> at the next major bump.
> The naming is good and reasonable consistent. To change it at the next maj ver
> bump there needs to be a problem in the existing naming and a better naming and
> consensus amongth the devels that the new is better and not just the yearly
> bikeshed style. Because every such change means everyone will have to update
> their applications and this is a lot of work when one considers how many
> applications there are. Not to mention the ones that try to support differnent
> lav* versions

I need to revive this thread since I've come up with a file that I want 

I disagree, Y400A is a very bad name since the gray plane is coded using 
0-255 and IMHO is not really similar to a Y plane IMHO in the YUV sense, 
if you want to call it Y then YJ400A at least.

I vote for GRAY8A, which is consistent to GRAY8 and to YUVA and RGBA, 
and after we don't call RGBA -> R8G8B8A8.
I'd be fine with GRAYA too.

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