Can YUY2 store 4:1:1 losslessly?

[shae]

I always forget what these annoying notations mean...

Is YUY2 4:2:2? Would 4:1:1 not lose chroma data when stored as YUY2?

(BTW, is there no RGB mode for ffdshow HuffYUV)?

[JohnnyMalaria]

It would be the other way around. 4:2:2 has 2 chroma samples per 4 luma samples vertically and horizontally. 4:1:1 has one chroma sample per 4 luma samples. Hence, YUY2 would simply duplicate each 4:1:1 chroma sample in each direction.

[Dark Shikari]

It would be the other way around. 4:2:2 has 2 chroma samples per 4 luma samples vertically and horizontally. 4:1:1 has one chroma sample per 4 luma samples. Hence, YUY2 would simply duplicate each 4:1:1 chroma sample in each direction.Actually, it would probably upscale the chroma with a resizing filter, so not exactly.

[shae]

Searching some more, I found 4:1:1 is 4 horizontal pixels per chroma vs 4:2:2's 2 h pixels, so it should do.

Dark Shikari: You mean the 4:1:1 might get interpolated before being output as 4:2:2?

[Dark Shikari]

Searching some more, I found 4:1:1 is 4 horizontal pixels per chroma vs 4:2:2's 2 h pixels, so it should do.

Dark Shikari: You mean the 4:1:1 might get interpolated before being output as 4:2:2?The encoder will convert your 4:1:1 to 4:2:2 before encoding. This probably isn't a problem.

[JohnnyMalaria]

Actually, it would probably upscale the chroma with a resizing filter, so not exactly.

That depends on the colorspace conversion implementation. I was being purist :)

[shae]

The encoder will convert your 4:1:1 to 4:2:2 before encoding. This probably isn't a problem.Unless it's being fed 4:2:2 (which is the likely case since most codecs accept YUY2).

[akupenguin]

BTW, is there no RGB mode for ffdshow HuffYUV?
I don't know what's enabled in ffdshow, but libavcodec huffyuv supports RGB.

[henryho_hk]

i really love the clear illustrations on this site: http://www.mir.com/DMG/chroma.html

[shae]

The illustration are nice. But it'd be nicer to have a few comparison shots of actual frames. :)

[JohnnyMalaria]

The illustration are nice. But it'd be nicer to have a few comparison shots of actual frames. :)

That can be difficult since to see the frames, the data have to be converted to RGB which, in turn, depends on the algorithm used (i.e., blend, interpolate etc).

[henryho_hk]

Try these: http://www.nattress.com/Chroma_Investigation/chromasampling.htm

Not exactly the same topic but you will get the idea.

[shae]

henryho_hk: That's an interesting page.

Thanks all.