[FFmpeg-devel] [PATCH] FLIF16 GSOC Project - Added RGB to YCoCg macros

[Lynne]

Mar 21, 2020, 09:24 by me at jailuthra.in:

> Please mark the patch as [WIP] or [RFC] if you are not sending it for a merge review.
>
> On Wed, Mar 18, 2020 at 11:01:22AM +0530, Kartik wrote:
>
>> From: Kartik K. Khullar<kartikkhullar840 at gmail.com>
>>
>> ---
>> FFmpeg/libavutil/colorspace.h | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/FFmpeg/libavutil/colorspace.h b/FFmpeg/libavutil/colorspace.h
>> index ef6f610..bf53afe 100644
>> --- a/FFmpeg/libavutil/colorspace.h
>> +++ b/FFmpeg/libavutil/colorspace.h
>> @@ -94,6 +94,17 @@ static inline int C_JPEG_TO_CCIR(int y) {
>>  return y;
>> }
>>
>> +#define RGB_TO_YCoCg(R, G, B, Y, Co, Cg){\
>> +	Y = (((R+B)>>1) + G)>>1;\
>> +    Co = R - B;\
>> +    Cg = G - ((R+B)>>1);\
>> +}
>>
>
> You don't need to take Y,Co,Cg as inputs to the macro, look at other similar macros.
>
> I would also suggest defining different macros for different output channels as it does not assume that Y,Co,Cg will be variables defined in the caller's context. Take a look at RGB_TO_Y/U/V_JPEG etc.
>
>> +
>> +#define YCoCg_TO_RGB(R, G, B, Y, Co, Cg){\
>> +	Y = (((R+B)>>1) + G)>>1;\
>> +    Co = R - B;\
>> +    Cg = G - ((R+B)>>1);\
>> +}
>>
>
> Only the name is inverse here, it still does the forward transform.
>
>>
>> #define RGB_TO_Y_CCIR(r, g, b) \
>> ((FIX(0.29900*219.0/255.0) * (r) + FIX(0.58700*219.0/255.0) * (g) + \
>> -- 
>> 2.20.1.windows.1
>>
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Why are you even adding those macros in? We don't covert colorspaces or pixel formats in the decoders. If you have a ycgco output just mark it as yuv420p with a ycgco colorspace.