Color spaces and capture cards

Color spaces and capture cards

on Dec 16, 2015 at 2:49:38 pm

I've been working on a project in Sony Vegas, and I want to export it through Lagarith to encode it with Handbrake. Lagarith has a setting to define the color space and I want to avoid pointless conversions. The footage has been recorded with an Elgato HD60 capture card, and I'm trying to figure out the color space and chroma subsampling the card is using. To figure this out I loaded this picture on a device:

https://i.gyazo.com/bc27d383257715aa11e1386957cb39f1.png

Then I recorded footage with the Elgato from it and checked if the recorded clip had any artifacts, but I didn't see any. I was puzzled because I assumed the capture card was working with 4:2:0 subsampling, so I uploaded the video to YouTube which should use 4:2:0 according to Google's recommended settings web page. Again I couldn't see any artifact where I should have (bottom rows). Am I doing something wrong?

Re: Color spaces and capture cards

by Eric Strand

on Dec 17, 2015 at 10:47:35 pm

You could try recording a sample clip and dropping the clip into MediaInfo to see the subsampling.

https://mediaarea.net/en/MediaInfo

@ericstrand11

Re: Color spaces and capture cards

on Dec 18, 2015 at 9:23:28 am

Thanks for replying. I did that already and MediaInfo says it uses 4:2:0, but I don't get it, if the content was actually 4:2:0 wouldn't I see artifacts like shown here?

http://www.geeks3d.com/20141203/how-to-quickly-check-the-chroma-subsampling...

Re: Color spaces and capture cards

on Dec 19, 2015 at 3:23:55 pm

Well I did some tests and using RGB in Lagarith produces the best results, so I assume that's the correct color space. Now I have another question, exporting out of Handbrake gives me a limited color range and I can't seem to figure out how to get the full 0-255 range. What can I do?

Re: Color spaces and capture cards

by Eric Strand

on Dec 22, 2015 at 4:13:19 pm

Hey Paolo, so after reading about the Elgato HD60, I think you're trying to kill a fly with a bazooka. The HD60 is a consumer product that connects to a person's laptop via USB 2.0 to record an H.264 stream at a maximum bitrate of 40mbps. Given those 4 points I believe it is safe to say the card captures a 4:2:0 signal in the 16-235 range. A USB 2.0 connection wouldn't be able to handle a 4:4:4 stream.

I'm not sure if Handbrake can do a 0-255 export, but you might want to try googling the x.264 parameters to see if it's possible. I would export a ProRes or Cineform file out of Vegas, compress that file in Handbrake at a CRF of 18-15 and then upload to YouTube.

@ericstrand11

Re: Color spaces and capture cards

on Dec 23, 2015 at 11:31:26 am
Last Edited By Paolo Di Noia on Dec 23, 2015 at 11:52:29 am

Hey Eric, thanks for replying. I've been trying to figure this out in the last few days, but I haven't kept this thread up to date (sorry). This is what I found out:

1. MediaInfo reports 4:2:0 for my capture card raw footage, however using 4:2:0 in Lagarith in Vegas produces a color shift that's not there if I use RGB, so when I export the video from Vegas I use RGB.

2. I found out how to set the color range to 0-255 in Handbrake (fullrange=on), however that washes out the colors, so I went back to limited range.

3. I did a lot of render tests and this is what happens:
RAW file -> Vegas Lossless AVI RGB 4:4:4 (Lagarith or UT Codec): no color shift.
RAW file -> Handbrake: no color shift.
RAW file -> Vegas Lossless AVI RGB 4:4:4 (Lagarith or UT Codec) -> Handbrake: COLOR SHIFT.

I don't understand what's going on, the Vegas output and the raw file are virtually identical. If I could I would skip using Vegas but that's not an option because I need to edit my videos and Vegas suits my needs.