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[Adhara]

Hi,

Some years ago, we must specified RGB for the outptut when using HTPC.
Explanation was video cards was not been able to work in YCbCr.
They are several issues doing that:

NO video processing happens in RGB mode. So if we select RGB output, signal is converted in YCbCr (for MC stuff) and converted a second time in RGB.
I know BLU-RAY disc is encoded in YCbCr 420 and My conviction is most of video are encoded in the same way. So YCbCr 4:2:2 is the best choice in most situations.

But most video cards will do the processing in RGB format. There is also a dicussion to avoid YCbCr Output from HTPC due to double conversion issue...


So the questions are:
- How to know if a video is encoded in RGB or YCbCr ?
- How to know if our own video card is YCbCr  capable (without performing double conversion) ?
   --> Mine is ATI Radeon 7750 and I can choose on catalayst center the output format (RGB full/limited, YCbCr full/limited).
   --> But I'm not sure if I select YCbCr, there is no RGB conversion during playback with MC.

Is there any Video card (pro or non pro) which guarantee to work fully  in YCbCr ?

Thanks for clarification.

[Hendrik]

A PC can not work in full YCbCr, there is always RGB involved with current graphics cards and the related software, and as such, you should also output RGB from your PC, to avoid one unnecessary low-quality conversion.
If you do video processing after your PC, its true that it'll most likely convert back to YCbCr, however, any good device will do this in higher precision then your GPU would when you force YCbCr output in the ATI control panel.

So in short, use RGB output for best quality.

PS:
You can also do video processing in RGB, there is no particular reason thats not possible, its just that YCbCr is easier, which is why video processors use the compromise in quality for lower complexity.

[Adhara]

A PC can not work in full YCbCr, there is always RGB involved with current graphics cards and the related software, and as such, you should also output RGB from your PC, to avoid one unnecessary low-quality conversion.
If you do video processing after your PC, its true that it'll most likely convert back to YCbCr, however, any good device will do this in higher precision then your GPU would when you force YCbCr output in the ATI control panel.

So in short, use RGB output for best quality.

PS:
You can also do video processing in RGB, there is no particular reason thats not possible, its just that YCbCr is easier, which is why video processors use the compromise in quality for lower complexity.

Thanks Hendrik,

Yes I use an external device for video processing (Lumagen Radiance 2041) which makes a "perfect" RGB to YCbCr conversion.
I should try using BD player (which naturaly work in YCbCr 422) in order to see if there is something different in term of quality Vs HTPC+MC.

Maybe some of users here did the test already.