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

[Michael Niedermayer]

On Sun, Jun 06, 2010 at 05:30:57PM -0700, Baptiste Coudurier wrote:
> On 6/6/10 5:15 PM, Michael Niedermayer wrote:
>> On Sun, Jun 06, 2010 at 02:51:59PM -0700, Baptiste Coudurier wrote:
>>> On 6/3/10 2:25 PM, Michael Niedermayer wrote:
>>>> On Thu, Jun 03, 2010 at 02:22:48PM -0700, Baptiste Coudurier wrote:
>>>>> On 06/03/2010 02:16 PM, Michael Niedermayer wrote:
>>>>>> On Thu, Jun 03, 2010 at 12:14:58PM -0700, Baptiste Coudurier wrote:
>>>>>>> On 06/03/2010 03:45 AM, Michael Niedermayer wrote:
>>>>>>>> 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.
>>>>>>>
>>>>>>> Then mark them as so,
>>>>>>
>>>>>> done
>>>>>>
>>>>>>
>>>>>>> and start changing the code, because I would
>>>>>>> personally not remove something that has been in the code so long ;)
>>>>>>
>>>>>> changing lavc is not hard but applications need to be changed too
>>>>>> and i just now marked it as deprecated ...
>>>>>> maybe we can add YJ400A as an intermediate workaround because the 
>>>>>> other
>>>>>> formats where not correctly marked as deprecated as i thought they 
>>>>>> where
>>>>>
>>>>> Whatever, I'm against this name, stefano as well.
>>>>> Shall we start a vote ?
>>>>
>>>> yes of course ;)
>>>> but first we should wait 48h for people to propose options
>>>>
>>>> currently we have
>>>> YJ400A
>>>> GRAY8A
>>>> GRAY8ALPHA8
>>>> GRAYALPHA8
>>>
>>> GRAY8A input support in libswscale :)
>> [...]
>>
>>> @@ -1062,6 +1063,14 @@
>>>       }
>>>   }
>>>
>>> +static inline void gray8aToA(uint8_t *dst, const uint8_t *src, long 
>>> width, uint32_t *unused)
>>> +{
>>> +    int i;
>>> +    for (i=0; i<width; i++) {
>>> +        dst[i]= src[2*i];
>>> +    }
>>> +}
>>
>> extract_even() or yuy2ToY() i think does this
>
> Indeed, nice :)
>
>> except that it looks ok, i assume its tested
>> swscale_example based testing would be ideal but hard if we only support 
>> input
>> without output
>
> Ok, so can I rename to GRAY8A ? :)

you cannot break ABI/API
beyond that i dont really care enough about the color

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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