Some loss of color red in output

[dennis.r]

Video output loses some color red when compared with input, you can see that directly with the preview mode side by side.

System profile
PC 4090 RTX 11900K Intel Windows 11

Have noticed this bug since new version beta, could have been an issue prior to version 3.

[tony.topazlabs]

Hi Dennis,

Does the same color shift occur when viewing the input and output videos in a separate app like VLC or Premiere Pro? Our team is currently looking into some colorspace issues in the in-app player, but most exported files don’t show the same issue when viewed outside of Video AI.

[dennis.r]

The previews in the application has a noticeable color shift, that is immediate and easy to notice, and yes I agree most files don’t show the same issue. The red color loss in output using Video AI, is a result at the level of AI Video restoring and the results are still very impressive.
Update: After the latest patches the problem in this particular case has been solved.

[jojje]

I’ve been down the color space rabbit-hole. One thing I noticed with VAI is that just like FFMPEG, it can make an incorrect guess regarding the color profile of a source clip when the clip doesn’t provide any hint (e.g. Rec.709 assumed when Rec.601 was the actual profile, or vice versa).

When my source clip has color space information in it, VAI seems to do the right thing. When it’s absent, it’s a coin-toss.

What you can do to confirm or falsify if this is the case is to check your clip using mediainfo or ffmpeg / probe.

E.g.

mediainfo clip.mp4 | grep -E "Color|Transfer|Matrix"

Color space                              : YUV
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Or

ffprobe -v 0 -select_streams v -show_streams clip.mp4 | grep color

color_range=tv
color_space=bt709
color_transfer=bt709
color_primaries=bt709

This clip will be handled correct by VAI.
When these hints are absent, then it seems to behave like ffmpeg’s auto detection. The latter seems to assume Rec.601 for clips smaller than 720p and Rec.709 for 720p and up.

Since I convert all my clips to Rec.709 regardless of resolution, this wreaked havoc in the color representation before I started to explicitly add the color metadata to the clips.

TLDR; If your source clips don’t have the color info embedded, that’s probably the reason you get color shifts.