color range option question

[byu]

Hi

I have a question regarding the options when setting the color range for a capture card. In the "properties" page of the capture device, there are three options under color range: "default", "limited", and "full". I understand what limited and full means, but what does "default" mean? Does OBS studio automatically detect whether the input feed is limited or full, or is default something set by the capture card manufacturer and I could be getting either limited or full depending on the make and model of the capture card?

Thanks for the help.

 

[Suslik V]

If you are talking about "Video Capture Device" properties of OBS, then:
Default – will select Full for RGB format and Limited (Partial) for the YUV stored videos (but this behavior may change depending on OBS version and build).

 

[Suslik V]

Use test images to determine what setting to choose Some, 8-bit test charts were in:

Guides (OBS Studio)

Guides for OBS Studio

obsproject.com

 

[PaiSand]

Don't mess with color range unless you know exactly what you're doing. Keep it as it comes when you add the source.

 

[byu]

If you are talking about "Video Capture Device" properties of OBS, then:
Default – will select Full for RGB format and Limited (Partial) for the YUV stored videos (but this behavior may change depending on OBS version and build).

thanks for the reply. Yes I'm referring to the video capture device property. I have a SDI capture cards from Magewell and I use them to capture video coming from an endoscope. So my Magewell SDI capture card would be Partial? Would the SDI capture card ever be Full on Default? I have a bunch of videos that were already captured using the Magewell SDI card with the color range setting set to Default, I want to know if they were Partial or Full. Also is it better to set the color range to Partial going forward? My understanding is SDI signals are always partial except for some really unlikely situations?

 

[Suslik V]

As far as I understand, by internal logic SDI specifies only speed for the digital connection. Format can be any.

...I have a bunch of videos that were already captured using the Magewell SDI card with the color range setting set to Default, I want to know if they were Partial or Full.

It is not easy task, because almost all video players (both hardware and software based) will scale limited (partial) range videos to full scale on the fly if the target device is full scale display device and vice versa. For example, default setting for output in OBS is Limited (Partial) color range, thus even if Video Capture Device source in OBS was fed with full range signal (and source itself was set to full range) - OBS scaled it down to limited (partial) range on the fly, without clipping or washing out, so OBS output remains limited range. Thus, you likely need to analyze spectrum of your videos to make guess if there too many similarities in the close colors.

If there wide areas of drops in colors: from 0 to 16 or above 235 (for 8-bit videos) then your settings for range in Video Capture Device source properties of OBS was wrong (OBS "thought" that video was limited when it actually was full range or vise versa).
Also, some hardware encoders may has it own limits and mistakes in implementations, like:

AMD HW AV1 with Color Range "Full" outputs wrong colors · Issue #9121 · obsproject/obs-studio

Operating System Info Windows 11 Other OS No response OBS Studio Version Other OBS Studio Version (Other) 29.1.3 OBS Studio Log URL https://obsproject.com/logs/lXfDZatEdQGpF247 OBS Studio Crash Log...

github.com

To get some visual results with free tools, you can try FFmpeg utils ("ffplay.exe"), command line:

ffplay "test.mkv" -vf "histogram"

it will draw small histogram in a new window, where you can visually, by distribution of colors, guess is video was wrongly scaled or not. Look at border areas where density of colors are at minimum (0-16; 235-255). YUV videos has Y, U and V histograms (white blue red), you need only Y (white/top). Example: https://github.com/obsproject/obs-studio/issues/8199#issuecomment-1447974174