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

Michael Niedermayer michaelni
Thu Jun 3 12:45:32 CEST 2010

On Wed, Jun 02, 2010 at 05:37:36PM -0700, Baptiste Coudurier wrote:
> 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 
> supported.
> 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.

the luma range, really is indicated by AVCodecContext.color_range
the J pixel formats are deprecated.
Thats mainly because there are far too many yuv variations than what
could be indicated by a few pixel formats.


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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