How to determine if capture card color matrix is correct?

[ENunn]

I'm having a little dilemma here about getting the most accurate colors my capture cards can show.

I usually capture off TV with my Elgato Game Capture HD60s with Amarec, and I noticed after a driver update that the colors were out of whack. I thought this would be a color matrix issue, so I emailed Elgato, they sent me a fixed beta driver, and it went back to normal.

However, comparing it to my Avermedia Live Gamer 4K, I don't even know what's right anymore. Here's some example screenshots.

On Demand Logos

Old/New Beta Elgato Driver

[Attachment 57440 - Click to enlarge]

New (non-beta) Elgato Driver

[Attachment 57441 - Click to enlarge]

Live Gamer 4K

[Attachment 57442 - Click to enlarge]

Live Shows

Old/New Beta Elgato Driver

[Attachment 57446 - Click to enlarge]

New (non-beta) Elgato Driver

[Attachment 57444 - Click to enlarge]

Live Gamer 4K

[Attachment 57445 - Click to enlarge]

Is there any way I can check and see if my cards are displaying in the right color matrix or not? Which one's correct and which one's not? I can send example videos if anyone wants any.

[jagabo]

Can you play youtube content on your source? This video has standard 75 percent rec.709 (aka bt.709) HD colorbars at about 45 seconds in:

https://www.youtube.com/watch?v=waUahh8DG4M

When displayed correctly the bars' RGB values should be 0 or 191, plus or minus 1 or 2. You have to make sure your player (cable box? satellite box?) isn't "enhancing" the playback in any way.

Or if you can play your own video file I recently uploaded a similar MKV video in this post:

https://forum.videohelp.com/threads/400746-Avisynth-ffvideosource-color-distortion?hig...rs#post2610904

You do have to make sure the player you are using is set up correctly too. Some players always use rec.601, some only rec.709. Some will switch to 601 for SD video, 709 for HD video. Some will follow the flagged colormatrix. The video I posted is HD, rec.709, and flagged as rec.709. So it has the best chance of being displayed correctly.

If you're not sure about your playback and analysis, upload a short sample of the captured colorbars.

[chris319]

Forget that YouTube video. The .mkv bars posted by Jagabo are accurate. You need a calibrated video source and a way of measuring the colors.

Use an eyedropper/color picker program to check the colors. For the color values, R, G and B should be either 16 or 180 +/- 3 points, e.g. yellow is r=180, g=180, b=16.

Some browsers used to use the BT.601 color space, ignoring flags. I and some others became squeaky wheels and the programmers finally switched to BT.709. That said, either YouTube or your browser tend to muck up color accuracy. Even the newer versions of VLC player muck up the colors. I have to use VLC 2.2.8 "Weatherwax" to get accurate colors.

[jagabo]

Forget that YouTube video. The .mkv bars posted by Jagabo are accurate.

It had the correct rec.709 colors when I looked at it last night. This morning I see bad colors. I see what's happening: if you view the video in a browser in a small windows you get one of the lower resolution videos with the wrong colors, if you view in a large enough window the colors are correct. The 480p and lower resolutions give the wrong colors, the 720p and 1080p resolutions give the correct colors. If you download the SD or HD videos and display them correctly as rec.709 you get the correct colors.


[Attachment 57457 - Click to enlarge]

But yes, this can be browser and graphics card dependent so you should verify the on-screen colors on your own system. In any case the downloaded videos have the correct rec.709 YUV colors.

Use an eyedropper/color picker program to check the colors. For the color values, R, G and B should be either 16 or 180 +/- 3 points, e.g. yellow is r=180, g=180, b=16.

No. If you are viewing this correctly on a computer monitor you should see RGB components of 0 or 191. We've been through all of this before.

[ENunn]

Thanks jagabo! I played the test file you posted on my Roku and it's accurate on the beta driver. At least now I won't have to worry about it anymore.

[chris319]

No. If you are viewing this correctly on a computer monitor you should see RGB components of 0 or 191. We've been through all of this before.

Yes we have.

I suggest you familiarize yourself with the specs. First, the spec for color bars is not EBU BT.709 but SMPTE RP 219. Work from there.

Unless something has changed since last night, your bars are accurate when downloaded and viewed with an older version of VLC as I described that doesn't mess up the luminance values.

I uploaded a test pattern to YouTube which not only has the correct RP 219 colors for 75% bars, which are most commonly used, but has text indicators of the values they are supposed to be. Either YouTube or Chrome is doing something to alter the colors. They're accurate when viewed with VLC on my machine. Either YouTube or the browser is messing them up. Now Chrome won't open my local mp4 file so I can isolate and test Chrome's color rendition.

I have done test after test on this stuff. Now I'm weary of doing tests.