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joncampbell123 / composite-video-simulator

Code to process video to simulate analog composite video.
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ringing? #15

Open zhuker opened 4 years ago

zhuker commented 4 years ago

can any of the binaries also generate ringing artifacts as described here https://bavc.github.io/avaa/artifacts/ringing.html image

joncampbell123 commented 4 years ago

That's a good one, it will give it that authentic "I was recorded in the mid 1980s" look since some master tapes from that time period seem to have it.

Look up practically any 1980s Computer Chronicles episode on the Internet Archive and you'll see it.

zhuker commented 4 years ago

@joncampbell123 whats a good way to emulate it?

joncampbell123 commented 4 years ago

I'm not sure at what point the ringing artifact is happening, so there are two possibilities for where to apply the filter.

If the ringing artifact only happens in the luminance channel, then apply it to the Y channel when it's still YIQ before separation to color subcarrier.

If the ringing artifact happened to the composite signal, then apply the filter when the frame is a black and white image with color subcarrier. The ringing artifact looks like it's not high frequency enough to screw up the color but high enough for the artifacts to cause false color.

All you need to write then is a routine that tracks the pixels vs a value that you add/subtract a weighted value against such that it deliberately overshoots and undershoots when the picture changes suddenly.