Comments

Spot|DSE wrote on 8/13/2009, 9:01 PM
Are you asking about color sampling or bits per channel?
Still 8 bits per channel, but color sampling can be 4:2:0 or 4:2:2
Streamworks Audio wrote on 8/13/2009, 9:11 PM
Yeah - sorry bits per channel is what I was after. So 8bits it is then?

Cheers,
Chris
Streamworks Audio wrote on 8/14/2009, 2:59 AM
Is that 8bits per channel regardless of the subsampling? Or does that the sampling change the amount of bits for each Y, U & V channels - or are those the actual channels?

Sorry guys - I mostly work with RGB/RAW stuff from Digital Cameras and computer generated images which are also RGB - I know that is 8bits per channel for most images (some are 16bit per channel like 16bit TIFFs) - but I am a little confused about video.... RGB is a Channel Type (sRGB is a color space) - CMYK is a channel type... but what is YUV (for MPEG2, AVC etc)? Is that a channel type and or color space? I know that it is 1 part luminance and 2 parts chrominance - but again not sure how that would relate to say channels.

Cheers,
Chris
farss wrote on 8/14/2009, 3:38 AM
Yes, 8 bpc regardless of sampling. The chroma sampling determines how many 8 bpc samples there are. So 4:2:2 is more data than 4:2:0. That means more chroma resolution.

In the video world it's traditionally referred to as YUV even though it almost never is. It's Y'CbCr, Luma and two difference values. Heaps of the good oil and all the maths on the web.

Video cameras internally may process the RGB data at 14bpc, no real difference between a video camera and a still camera in that regard. One signifcant difference is the need for speed and how fast and vast the media is for storing the data.

Bob.
Streamworks Audio wrote on 8/14/2009, 6:25 PM
Thanks Bob,

I think I get what your saying.... not 100% sure but enuff to get me going on reading up ;-)

I guess it doesn't matter for when working in Vegas as it turns all my AVCHD clips to RGB format anyways when the clips are put on to the time line. Going back to Y,Cr,Cr is doing by the encoder when rendering it.

I just like to know how these things work :-)

Chris