x264 and profile High422 8 bits

[Famille_CB]

Hello,

I would like to know if x264 can use the profile high422 but in 8 bit depth for luma and chroma.
I ask for this because I made tests with Mainconcept Reference with this profile in 8bit and the colours were perfect. The bad side of this tool/codec (Mainconcept Reference) is that I can't find good ratio space on hard disk/quality. X264 is better.

For your information see below how I work:
Sony Vegas --> Debugmode Frameserver (http://www.debugmode.com/frameserver/) --> Staxrip. Staxrip encode audio + video (x264 + ogg) then mux this in MKV.
Everything is perfect except that colours are a little bit "Washed".

Then can you help me?

Thank you.

[Blue_MiSfit]

This is more than likely a TV vs PC levels issue, and is probably not x264's fault.

[Famille_CB]

Hello,

Actually my rushes comes from a camcorder : Canon HV20 (HDV). I read somewhere that the codec is mpeg-2 which use a 4:2:0 colour space.
I put on my files (in Sony Vegas) a correction "Studio RGB to Computer RGB". At this moment colours are OK.

The strange thing is that I use the same way for Mainconcept Reference and Staxrip. And the colours results are different.

And the difference I can see is that with Reference the profile is high422.
When I encode with Reference with a profile high standard I have the same issue on colours.

Do you see what I mean? Can you help me?

Thank you.

[Blue_MiSfit]

This has nothing to do with 4:2:0 versus 4:2:2. You should always be using 4:2:0 in this case, unless you're planning on doing things like chroma key downstream.

I think the issue lies with your application of the "Studio RGB to Computer RGB" filter. Why do you do this? You're changing limited range (aka studio aka TV aka 16-235) video coming out of your camcorder into full range (aka computer aka PC aka 0-255) video.

The reason that you get different results in MainConcept is that it probably detects that the video is full range, and flags this in the bitstream.

How are you comparing the results of x264 and Mainconcept? Also, posting some samples would be very helpful.

Derek

[Famille_CB]

OK, I'll post samples as soon as possible.

Thank you.

[poisondeathray]

It has nothing to do with chroma subsampling. The reason is when you use vegas' default settings, it converts Y'CbCr to RGB using studio RGB, not sRGB (also called computer RGB)

Native camera files use Y'CbCr. When importing into vagas, Y'CbCr 0-255 is "mapped" to RGB 16,16,16 - 235,235,235 , instead of 0,0,0-255,255,255

Most programs use and expect sRGB (black is at 0,0,0, white is at 255,255,255)

So when you use debugmode out of vegas you need to converttoYV12 using a PC matrix instead of a Rec matrix to expand the range back (because the data had been mapped to RGB 16-235)

e.g.

AVISource("debugmode.avi")
ConvertToYV12(matrix="PC.709")