[FFmpeg-cvslog] r27730 - in trunk/libswscale: swscale.c swscale_internal.h

[Michael Niedermayer]

On Mon, Oct 20, 2008 at 06:27:36PM +0200, Vitor Sessak wrote:
> Michael Niedermayer wrote:
>> On Sun, Oct 19, 2008 at 08:25:41PM +0200, Vitor Sessak wrote:
>>> Michael Niedermayer wrote:
>>>> On Sat, Oct 18, 2008 at 11:55:58PM +0200, Vitor Sessak wrote:
>>>>> vitor wrote:
>>>>>> Author: vitor
>>>>>> Date: Wed Oct  8 19:46:22 2008
>>>>>> New Revision: 27730
>>>>>> Log:
>>>>>> Add a new unscaled PAL8 -> RGB converter.
>>>>> 1000l for me for this patch. I tested it, but without noticing that 
>>>>> typing "make" do _not_ rebuild swscale-example. Actually it made a 
>>>>> small regression in {PAL,RGB8,BGR8,RGB4,BGR4}->{RGB32, BGR32}.
>>>>>
>>>>> Three possibilities:
>>>>>
>>>>> 1- Revert it
>>>>> 2- sws_fix10l.diff: fix the actual bug (in rgb2rgb.c)
>>>>> 3- sws_hack.diff: just fix my breakage
>>>> i do not think 2 or 3 fix the code
>>>> the palette is in RGB32 format IIRC so one side of the #ifdef has to be
>>>> wrong. Also the rgb24 would need ifdefs which it does not have, or the
>>>> palette would have to be converted into a differnt byte order or the
>>>> switch case would need to be changed a little
>>> AFAIK, before the palette was either in BGR32 or RGB32 depending on 
>>> alignment. Now I've made everything alignment independent. Also, if I 
>>> understand correctly the code, I think that swscaler uses a slightly 
>>> unusual definition of RGB/BGR.
>> the swscaler uses the same definition as lav* uses, and its very similar
>> to mplayers except some rgb <-> bgr flips
>> These definitions have also been choosen that way for efficiency and
>> simplicity.
>> anyway, this patch doesnt look correct either
>> i suggest you read the definition of the formats in avutils.h
>
> Documented header files are a bliss =)
>
> Hopefully correct version attached.
>
> -Vitor

[...]
>  void palette8tobgr32(const uint8_t *src, uint8_t *dst, long num_pixels, const uint8_t *palette)
>  {
>      long i;
> -    for (i=0; i<num_pixels; i++)
> -    {
> -        #ifdef WORDS_BIGENDIAN
> -            dst[3]= palette[src[i]*4+0];
> -            dst[2]= palette[src[i]*4+1];
> -            dst[1]= palette[src[i]*4+2];
> -        #else
> -            //FIXME slow?
> -            dst[0]= palette[src[i]*4+0];
> -            dst[1]= palette[src[i]*4+1];
> -            dst[2]= palette[src[i]*4+2];
> -            //dst[3]= 0; /* do we need this cleansing? */
> -        #endif
>  
> -        dst+= 4;
> -    }
> +    for (i=0; i<num_pixels; i++)
> +        ((uint32_t *) dst)[i] =
> +            bswap_32(((const uint32_t *) palette)[src[i]]) >> 8;
>  }

i think it would be faster to bswap 256 entries in palette than
width*height, besides this would allow the same code to be used for
rgb & bgr

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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