[nickr]

"Reference" was perhaps the wrong word. But IMHO nVidia gives best video output still.

[Stereodude]

I get that the video we're consuming is in YUV format and if I understand correctly YUV->RGB can be performed losslessly, though there can be loss when converting 16-235 to 0-255 for an RGB display. But weather you convert to RGB before output or you output YCbCr, the display itself ultimately takes or converts to RGB for rendering to it's pixels. So assuming there's no filtering/post processing happening, how much change can really happen to the image between decoding and display?

PC's work in RGB color. Outputting YCbCr from a PC device is not a good idea because you're double converting it (YUV -> RGB -> YUV). Converting YUV 16-235 to 0-255 RGB is no more lossy than converting YUV 16-235 to 16-255. In most cases converting 0-255 RGB is a better choice if your display can be set up to accept it.

A lot can visibly change if you're upscaling from say 480p to 1080p. Also, unless you have YUV 4:4:4 you're always upscaling the chroma. Even for 1080p Blu-Ray to a 1080p display. However, differences in chroma upscaling in the 1080p Blu-Ray scenario are very subtle. Then there's the topic of dithering since the YUV -> RGB conversion is floating point math and there are quantization steps...

There are lots of places to go wrong.

[DJ_Izumi]

There are lots of places to go wrong.

In the case of YCbCr, I was referring to a Blu-ray player that could process and output YCbCr and not do an RGB conversion. I realize multiple color space conversions in a PC would be detrimental (and pointless). Though my point was, no matter what you do, it HAS to be converted to RGB eventually since all displays are untimely RGB.

[noggin]

Yeah... I just gotta ask, what is all this 'reference' stuff when we're talking about digital video?

I get that the video we're consuming is in YUV format and if I understand correctly YUV->RGB can be performed losslessly, though there can be loss when converting 16-235 to 0-255 for an RGB display. But weather you convert to RGB before output or you output YCbCr, the display itself ultimately takes or converts to RGB for rendering to it's pixels. So assuming there's no filtering/post processing happening, how much change can really happen to the image between decoding and display?

De-interlacing is a key issue for 480i, 576i and 1080i content.

Correct handling of YCrCb 601 and 709 colourspace conversion is an issue (ironically converting to RGB may help with SD 601 YCrCb playback over an HD 709 YCrCb connection - as they have different RGB matrix co-efficients).

Proper handling of 16-235 levels. Decent 4:2:0 to 4:2:2 or 4:4:4 re-sampling.

[noggin]

There are lots of places to go wrong.

In the case of YCbCr, I was referring to a Blu-ray player that could process and output YCbCr and not do an RGB conversion. I realize multiple color space conversions in a PC would be detrimental (and pointless). Though my point was, no matter what you do, it HAS to be converted to RGB eventually since all displays are untimely RGB.

And DVD replay on a Blu-ray player with HD upscaling would need a rematrix as well as DVDs are 601 and HD is usually 709. Totally different RGB<->YCrCb matrix for 601 and 709.

[noggin]

I get that the video we're consuming is in YUV format and if I understand correctly YUV->RGB can be performed losslessly, though there can be loss when converting 16-235 to 0-255 for an RGB display. But weather you convert to RGB before output or you output YCbCr, the display itself ultimately takes or converts to RGB for rendering to it's pixels. So assuming there's no filtering/post processing happening, how much change can really happen to the image between decoding and display?

PC's work in RGB color. Outputting YCbCr from a PC device is not a good idea because you're double converting it (YUV -> RGB -> YUV). Converting YUV 16-235 to 0-255 RGB is no more lossy than converting YUV 16-235 to 16-255. In most cases converting 0-255 RGB is a better choice if your display can be set up to accept it.

Aren't you clipping transients with a 16-235 YCrCb to 0-255 RGB conversion, whereas these are preserved in 16-235 RGB conversion. If it's the last stage in the chain then that isn't an issue - but if you are feeding into an Amp or Display that is re-scaling, that could cause an issue with clipping which causes ringing.