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Old 1st February 2016, 16:51   #1  |  Link
ron spencer
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MeGUI Colour Space Warning

Hey all,

I have been learning with fun how to make bluray compatible output with MeGUI. Not so hard.

But I have an issue. I am starting with DNxHD files that are YUV output. MeGUI gives me a warning before I encode to change the color space to YV12. My output files are YUV. So why is MeGUI wanting to convert to YV12? Not sure if this alters the final quality or not, but if it does I'd like to fix it. The only AVISynth command used is a crop. So not sure why this warning pops up as the end output is YUV, the same as the source.

thanks
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Old 1st February 2016, 17:00   #2  |  Link
poisondeathray
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Different chroma subsampling for YUV ; DNxHD is usually 10bit 4:2:2 (but there are other variants), Blu-ray only supports 8bit 4:2:0
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Old 1st February 2016, 19:21   #3  |  Link
ron spencer
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by dnxhd is 8 bit...and you are right, it is 4:2:2 for chroma sub-sampling. But is it a waste to change colour space from YUV to YV12 and then back to YUV? I guess I need to to get to 4:2:0. Will this introduce any quality issues? I don't see any I think.
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Old 1st February 2016, 19:33   #4  |  Link
poisondeathray
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Quote:
Originally Posted by ron spencer View Post
by dnxhd is 8 bit...and you are right, it is 4:2:2 for chroma sub-sampling. But is it a waste to change colour space from YUV to YV12 and then back to YUV? I guess I need to to get to 4:2:0. Will this introduce any quality issues? I don't see any I think.
YV12 is YUV. Think of "YUV" as the broader family. YV12 is a subset of YUV, specifically 4:2:0 planar. YV12 is required for BD

http://www.fourcc.org/yuv.php

The only things to remember in avisynth are if your content is interlaced, you must use the interlaced=true switch, and the correct matrix (usually Rec709 for HD and 601 for SD) if coming from a non YUV source
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Old 1st February 2016, 22:10   #5  |  Link
ron spencer
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ok thanks.

So if my source is 4:2:2 and 8 bit, YV12 converts it to 4:2:0 for bluray.

So my last question

Media info reports my encoded file (with right tags for Rec709 via MeGUI) as YUV. Is it right that is reports this as opposed to YV12 as you said YV12 is required for Bluray? Or is it just stating YUV as the broader family?

thanks for your input!
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Old 1st February 2016, 23:32   #6  |  Link
poisondeathray
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Quote:
Originally Posted by ron spencer View Post
ok thanks.

So if my source is 4:2:2 and 8 bit, YV12 converts it to 4:2:0 for bluray.

So my last question

Media info reports my encoded file (with right tags for Rec709 via MeGUI) as YUV. Is it right that is reports this as opposed to YV12 as you said YV12 is required for Bluray? Or is it just stating YUV as the broader family?

thanks for your input!

I think it' s just reporting the broader family (and it can make mistakes, I wouldn't rely on it to heavily)
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