Green line artifact on right side of gif

[brumm]

The bounty for this issue now applies to #183 instead.

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Hey,

I'm seeing green artifacts on the right side of the resulting gif. The input video file is taken straight from the Mojave screen recording tool.

Here's a sample:

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[sindresorhus]

Could you share the original recording? (Just ZIP it and attach it here) So I can reproduce it locally.

[brumm]

Sure thing!

Screen Recording 2019-03-14 at 15.53.36.mov.zip

[sindresorhus]

I can reproduce the problem when converting the video to PNG frames using ffmpeg too:

$ ffmpeg -i "Screen Recording 2019-03-14 at 15.53.36.mov" frame%04d.png

This is what I end up with:

[sindresorhus]

I think it's because the dimensions of the video is 384x529, which is a problem, as both sides have to be divisible by 4.

@kornelski Any thoughts what we could do about this?

[kornelski]

If AVFoundation and ffmpeg both agree that there's a green line there, there's a green line there. It might be caused by Mojave encoding the video incorrectly, so I'd report that to Apple as a bug in the screen recording tool.

But I think odd sizes of videos are "legal" in general. Internally they may need to be padded, which is a pain to deal with, but should be supported (e.g. JPEG only supports multiplies of 8 or even 16, but you can have any size after conversion).

The cause of this is probably an off-by-one error in computation of the size of the chroma channel. If you really wanted a workaround for this, you could try decoding the video into planar YUV format. Assuming you'd get YUV bitplanes in the right sizes (without that garbage line), you could then resize chroma with appropriate padding to match luma's size.

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[sindresorhus]

Closing as I agree this is not something we should fix. The bounty now applies to #183 instead.