i imported video files from my sony HDR-XR150 ( whis is HD AVCHD handycam) to vegas pro.12
and vegas recognizes it as 1920x1080x12, what does 12 mean here?
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Probably 12 bits per pixel (8 bit YUV with 4:2:0 chroma subsampling). 1920x1080 luma with 960x540 chroma.
RGB (in standard 4:4:4 mode) uses 8 bits for each color primary for each and every pixel: 8 + 8 + 8 = 24bits
YUV, in full 4:4:4 color sampling mode also uses 24 bits in the same way (just organized differently since no color primaries).
YUV, in standard professional 4:2:2 color sampling mode uses 8bits for the Y (luma), 8bits for every other U and 8bits for every other V (the 2 chroma values), or (averaged) 8 + 8/2 + 8/2 = 8 + 4 + 4 = 16bits
YUV, in standard consumer 4:2:0 color sampling mode uses 8 for Y, 8 for every other U and V, but on every other line, so that averages out to 8 + (8/2 /2) + (8/2 /2) = 8 + 2 + 2 = 12bits
Hopefully that will clear everything up. There are other real-world examples beyond these (<8-10-12-14-16-32> bits per color, other sampling options, addition of Alpha, etc), but these are currently the most commonly found.
**(Actually the 2nd & 3rd YUV numbers correspond to the H and V siting of BOTH the U and V sampling, not to separate respective U and V, but for illustration purposes, it ought to get the point across).
Last edited by Cornucopia; 17th Apr 2014 at 02:37.
tnx but are more or less bits any different?
thank you guys
If you want to see the practical repercussions of 4:2:0 chroma subsampling see the image in this post:
White text on a black background (or vice versa) would look the same with both 4:4:4 and 4:2:0 because greyscale information is stored at the same resolution.