Testing MrMC 3.7.0 - [Invites Closed]

[cosmoxl]

I've made lanczos3 as default scaler and I guess it's working.

However, when 720p50/60 videos are played and 720p50/60 is output the scaler used is nearest neighbor.

I understand that no luma scaling is having to be done as the resolutions match, but there's always chroma upscaling isn't there?

[davilla]

I've made lanczos3 as default scaler and I guess it's working.

However, when 720p50/60 videos are played and 720p50/60 is output the scaler used is nearest neighbor.

When display matches video, there is no scaling, yes ? It would be a 1:1 pixel match.

[koying]

I understand that no luma scaling is having to be done as the resolutions match, but there's always chroma upscaling isn't there?

Upscalers are applied on the RGB tranformation of the YUV frames.
Interpolating chroma doesn't make sense, as 1 chroma pixel applies to 4 luma pixels per definition (for yuv420).

[cosmoxl]

I've made lanczos3 as default scaler and I guess it's working.

However, when 720p50/60 videos are played and 720p50/60 is output the scaler used is nearest neighbor.

When display matches video, there is no scaling, yes ? It would be a 1:1 pixel match.

Davilla, you really need to read everything I write. I explained why I was still concerned about the scaler in the next sentence.

Chroma is always upscaled to the luma size, then further scalers are used if needed. So, there's still need for hi quality scalers as far as I understand.

[cosmoxl]

I understand that no luma scaling is having to be done as the resolutions match, but there's always chroma upscaling isn't there?

Upscalers are applied on the RGB tranformation of the YUV frames.
Interpolating chroma doesn't make sense, as 1 chroma pixel applies to 4 luma pixels per definition (for yuv420).

Then why does madvr make such a fuss over chroma upscaling?

[wesk05]

If you don't interpolate, how do you get to 4:4:4 or 4:2:2 from 4:2:0. Chroma upsampling is required for all output modes except 4K 50/60Hz 4:2:0 (Even for this I'm not sure whether it is perfectly 1:1).

[cosmoxl]

If you don't interpolate, how do you get to 4:4:4 or 4:2:2 from 4:2:0. Chroma upsampling is required for all output modes except 4K 50/60Hz 4:2:0 (Even for this I'm not sure whether it is perfectly 1:1).

exactly

[wesk05]

I haven't seen any BT.2020 to BT.709 gamut mapping code in Kodi. Even the HDR tonemapping code seems to be flawed. It seems to be assuming that the source gamma correction is 2.4 for PQ transfer.

[koying]

If you don't interpolate, how do you get to 4:4:4 or 4:2:2 from 4:2:0. Chroma upsampling is required for all output modes except 4K 50/60Hz 4:2:0 (Even for this I'm not sure whether it is perfectly 1:1).

Maybe we don't understand each other.

Per definition (for 4:2:0, still), 1 chroma applies to 4 luma. You don't "upscale" the chroma, you just apply the same chroma to 4 pixels. If you interpolate those chroma pixels, you are breaking the YUV definition.

We are still talking about the 720p image on a 720p resolution, from cosmoxl example, ofc.

[cosmoxl]

If you don't interpolate, how do you get to 4:4:4 or 4:2:2 from 4:2:0. Chroma upsampling is required for all output modes except 4K 50/60Hz 4:2:0 (Even for this I'm not sure whether it is perfectly 1:1).

Maybe we don't understand each other.

Per definition (for 4:2:0, still), 1 chroma applies to 4 luma. You don't "upscale" the chroma, you just apply the same chroma to 4 pixels. If you interpolate those chroma pixels, you are breaking the YUV definition.

We are still talking about the 720p image on a 720p resolution, from cosmoxl example, ofc.

Even in my example of 720p output as 720p the quarter size chroma layer still has to be upscaled to the luma reslution of the video. If nearest neighbor is used for that, that's bad.