Re: [Libquicktime-devel] Prores codec issues.

[Al C. <al...@dn...>]

The better solution was to fix the actual bug..

In the colorspace_macros.h

#define YUV_10_TO_RGB_24(y,u,v,r,g,b) \
   i_tmp=(yj_16_to_rgb * (y-0x40) + vj_16_to_r * (v-0x200))>>18;        \
   r = RECLIP_8(i_tmp);\
   i_tmp=(yj_16_to_rgb * (y-0x40) + uj_16_to_g * (u-0x200)+ vj_16_to_g * 
(v-0x200))>>18; \
   g = RECLIP_8(i_tmp);\
   i_tmp=(yj_16_to_rgb * (y-0x40) + uj_16_to_b * (u-0x200))>>18; \
   b = RECLIP_8(i_tmp);

should actually be

#define YUV_10_TO_RGB_24(y,u,v,r,g,b) \
   i_tmp=(y_16_to_rgb * (y-0x40) + v_16_to_r * (v-0x200))>>18;        \
   r = RECLIP_8(i_tmp);\
   i_tmp=(y_16_to_rgb * (y-0x40) + u_16_to_g * (u-0x200)+ v_16_to_g * 
(v-0x200))>>18; \
   g = RECLIP_8(i_tmp);\
   i_tmp=(y_16_to_rgb * (y-0x40) + u_16_to_b * (u-0x200))>>18; \
   b = RECLIP_8(i_tmp);

It was using the full range functions by mistake, output is now correct.

cheers

On 07/11/12 17:48, Burkhard Plaum wrote:
> Hi,
>
> Am 07.11.2012 17:50, schrieb Al Crate:
>> You can easily see this by running lqt_transcode on a prores mov.
>>
>>
>>
>> On 07/11/12 12:00, Al Crate wrote:
>>> Hi, have been playing with the ProRes codec, seems to encode correctly,
>>> but on decode the output is noticeably darker than the original.
>>>
>>> Has anyone else noticed this ?
>>>
>>> I've tried using ffmpeg directly and that works as expected. So I'm
>>> suspecting libquicktimes conversion from YUV422P10 to RGB888.
>>>
>
> Well then you can fix the conversion or bypass the built in colormodel converter
> completely. It's incredibly inefficient and only here for compatibility reasons.
>
> Too dark video is often related to a confusion of video scaled and JPEG scaled
> YCbCr. Not sure if that applies here.
>
> Burkhard
>
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