Renpy forcibly plays the video in the bt601 color space.

[Art4D]

Hi. Renpy always plays videos in the bt601 color space, which is why videos in the bt709 color space distort colors.

Initially, I render the video in mp4 (x264) with the standard settings. Next I will convert it to Webm(vp8) using ffmpeg.

If I convert it with bt709 color space, then the video is displayed correctly everywhere, different browsers, different media players, but in Renpy the video gets color distortion.

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ffmpeg -i video.mp4 -c:v vp8 -crf 4 -b:v 30M -colorspace bt709 -color_primaries bt709 -color_trc bt709 -color_range pc -y video_709.webm

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METADATA: Video: vp8, yuv420p(pc, bt709, progressive), 2560x1440, SAR 1:1 DAR 16:9, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)

If I convert it with the bt601 color space, then I need to additionally assign a filter -vf "colormatrix=bt709:smpte170m" so that the color matches the video with bt709. After conversion, the video will be displayed correctly in media players and renpy (without color distortion), but browsers will distort the color.

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ffmpeg -i video.mp4 -c:v vp8 -crf 4 -b:v 30M -colorspace smpte170m -color_primaries smpte170m -color_trc smpte170m -color_range pc -vf "colormatrix=bt709:smpte170m" -y video_601.webm

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METADATA: Video: vp8, yuv420p(pc, smpte170m, progressive), 2560x1440, SAR 1:1 DAR 16:9, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)

*Smpte170m is BT.601 NTSC

Now I have to create two files in bt601 for renpy and bt709 for everything else.
I would like renpy to read the metadata and show the video in the color space that is specified in them. This will help to avoid distortion of colors.

[PyTom]

I don't think color spaces is a direction that I want to take Ren'Py in, at least not any time soon. Most notably, because I don't completely understand them myself, and also because it seems like a way to lose information and quality, compared to dedicated tools. I'd suggest converting them into the RGB colorspace, like you are above, at which point Ren'Py will play them back properly.

[Art4D]

I don't think color spaces is a direction that I want to take Ren'Py in, at least not any time soon. Most notably, because I don't completely understand them myself, and also because it seems like a way to lose information and quality, compared to dedicated tools. I'd suggest converting them into the RGB colorspace, like you are above, at which point Ren'Py will play them back properly.

The fact is that bt601 is already an outdated color space created for TV. For PC, bt709 is used almost everywhere.
It would be more logical to use bt709 by default, since most PC videos have this color space.

It definitely does not affect the quality of the video, only the color.
If the bt601 video is converted to bt709, it will have a yellowish tint.
If bt709 is converted to bt601, it will have a reddish tint. (as it is happening now in renpy).

But you're partly right, even browsers still can't display color spaces properly, for some reason, my Google Chrome converts my videos from bt601 to bt709 (a yellowish tint is added).

[Imperf3kt]

For some context, bt601 is SD colorspace, while bt709 is HD colorspace.
The difference is barely noticeable on anything less than a 10bit display (most monitors and TVs are 6bit) so it's not a huge issue in my opinion.

[Art4D]

The difference is barely noticeable on anything less than a 10bit display

The difference is noticeable. I have an 8-bit monitor and I can clearly see this difference. I don't like that renpy puts a "red filter" on my videos.
Here is another user gave examples, you can take a look.

it's not a huge issue in my opinion.

Yes, this problem does not require an urgent solution.

[tapanojum]

Sorry for resurrecting an old thread but I just found this after searching about this same issue. I find this to be a pretty noticeable issue when using Movie(play='movie.webm', start_image = 'image1.webp', image = 'image100.webp'). You can see at the exact point that the playback switches from video to image as the colors look noticeably different.

Does anyone have a good workflow for this? Any good open source software that can convert the renders to BT601 so that the playback matches? FFmpeg should handle single renders, right?

Thanks

edit: Nvm, I used Shutter Encoder to encode the video as OP did.