[FFmpeg-devel] lavfi state of affairs

Baptiste Coudurier baptiste.coudurier
Fri Feb 6 20:39:30 CET 2009

Hi Michael,

On 2/6/2009 5:08 AM, Michael Niedermayer wrote:
> On Fri, Feb 06, 2009 at 10:37:51AM +0100, Michael Niedermayer wrote:
>> kOn Thu, Feb 05, 2009 at 07:55:24PM -0800, Baptiste Coudurier wrote:
>>> On 2/5/2009 7:15 PM, Michael Niedermayer wrote:
>>>> On Thu, Feb 05, 2009 at 05:26:33PM -0800, Baptiste Coudurier wrote:
> [...]
>>>>>>> Besides does this mean that gif encoder is right to use PAL8,
>>>>>>> and libswscale is supporting PAL8 but misuse BGR8 ?
>>>>>> i dont understand what you mean
>>>>> You said that libswscale supports PAL8 however it isSupportedOut
>>>>> does not accept PIX_FMT_PAL8.
>>>>> Can we refer in terms of PIX_FMT_* please ?
>>>>> I don't understand anything of what you explain, yet Im dev, how
>>>>> can you expect a user to understand ?
>>>> There is a 8 bit paletted format (PIX_FMT_PAL8) it can have an
>>>> arbitrary palette. There is a 8 bit paletted format (PIX_FMT_BGR8)
>>>> that has a single systematic 884 palette. There is a 8 bit paletted
>>>> format (PIX_FMT_XXX) that has a single systematic 666 palette.
>>>> imgconvert supports outputting PIX_FMT_XXX (while using the enum
>>>> value of PIX_FMT_PAL8 for it incorrectly due to lack of a
>>>> PIX_FMT_XXX) swscale supports outputting PIX_FMT_BGR8 neither support
>>>> arbitrary palettes nor the others systematic palette if they support
>>>> PIX_FMT_PAL8 is a matter of philosophy you could say both do because
>>>> each support a systematic paletted 8bit format or you could say
>>>> neither does because neither supports an arbitrary palette
>>>>> Libav* user looks and see: "OH gif uses PAL8", then he setups
>>>>> libswscale and libswscale chokes saying PAL8 unsupported. What does
>>>>> he do ? He will use imgconvert !
>>>> iam not going to fix imgconvert which would mean make it reject PAL8
>>>> add a RGB666 and make it accept that instead and then add RGB666,
>>>> PAL8, BGR8 and RGB8 to gif
>>>> i will simply ignore imgconvert and fix gif+swscale i hope this will
>>>> end this discussion because honestly iam sick of it.
>>> I'm sad to hear that finally explaining non obvious parts makes you 
>>> being sick.
>> what makes me sick is that you talk about bugs in gif.c and utils.c as
>> if they where bugs in swscale.
>> it works with imgconvert because it has matching bugs that cancel the
>> effect of bugs in utils.c
>> but let us rather fix the issues instead of continuing this discussion
> as promissed, ive fixed gif + swscale, also note that not a single byte
> in libswscale/* was changed all the issues where in imgconvert* utils.c
> and gif.c
> also ive added 2 lines clarifying the 8bpp formats in relation to palettes
> and gifs now look vastly better than before and you can also make grayscale
> and 16color gifs as a sideeffect

Thanks a lot for your efforts, this is greatly appreciated.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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