youtube player slightly shifts the colors of my video

[codemaster]

I uploaded a 720p mkv file to YouTube. When I view it on the YouTube player using the Chrome web browser, all colors are slightly shifted. Green grass and white objects have a slight but noticeable red tint that is not present in the source mkv file.

And when I view it on the YouTube player using the Firefox web browser, there is a slight red tint, but not as much as there is in Chrome.

I downloaded the mp4 file from YouTube Studio, and opened it with PotPlayer, and it doesn't have that slight red tint. Colors look identical to those in the source mkv file opened in PotPlayer.

Is there something I can do to the mkv file before uploading it, to prevent the YouTube player from displaying colors in an innacurate way?

[davexnet]

Could be a rec.601 Vs. rec.709 thing, perhaps somebody more familiar with youtube's behavior could conform/deny.
Or you could re-encode your source flagged properly at rec.709 and see if YT still does it ...

[codemaster]

I uploaded 4 short test mp4 clips at 720p encoded with bt470bg, smpte170m, bt709, and undef in the colormatrix parameter of x264. All 4 of them have the same red tint in YouTube player, but do not have the red tint in PotPlayer.

The source is 576i and bt470bg. It was deinterlaced and upscaled to 720p.

Is it because YouTube player ignores bt470bg and assumes bt709?

Can bt470bg input be converted to bt709 in AviSynth+?

ColorMatrix(mode="Rec.601->Rec.709")

Is this the correct line to add to the avs script?

[davexnet]

Use AVSPmod to open the source, and switch back and forth between the color matrix to see if
you can recreate the problem

[codemaster]

After I did more tests I found out that the slight shift in colors is caused by the web browser, not by the YouTube web app like I initially suspected.

Firefox causes a color shift towards red, so small that it is not noticeable, colors look almost identical to those in the NLE's preview window.

But Chrome causes a color shift so big, that I can clearly notice that they are shifted towards red, when compared side by side with the colors in the NLE's preview window.

So I was doing the RGB to YUV conversion properly in AviSynth+, and specifying the proper color matrix in the x264 parameters, and Chrome was doing YUV to RGB conversion in an innacurate way. If I download the youtube clip from youtube studio, and open it with PotPlayer, PotPlayer does YUV to RGB differently than how Chrome does it, because in PotPlayer colors look identical to those in the NLE's preview window.

[sluggerb]

Youtube released an update that changes how their video player plays videos. It vastly over saturates the video and shifts the color profile towards red. This is done in the YouTube player for various platforms, and is being rolled out over time. Chrome and Android video players were updated a few months ago, Roku was updated 2 days ago.

Why YouTube is going out of their way to make videos look like supersaturated hot garbage is anyone's guess. They aren't saying. As you saw playing the video in a different player like PotPlayer does not cause the effect, which proves it is YouTubes video player at fault here.

There is no way to fix it since this is entirely on YouTube's side. You can complain but Google is the #1 champion of not giving a crap what its users think of their products