Avisynth recommendations for vhs capture noise

[gamjerr]

Hi all,

I have some raw avi vhs captures with this type of noise profile (1-frame snow - probably dirty heads?). I am wondering what a good avisynth script might be to reduce/eliminate while encoding? - my typical avisynth script is just qtgmc and crop. It usually takes me quite a bit of time to get all dependencies together to try some of the external avisynth filters - I was hoping someone might have experience with just this problem and could save me time on trial/error of different denoisers.

Any suggestions? Sample attached. Thanks,

[johnmeyer]

Search in the forum and in doom9.org for the word "comets." That is what those horizontal streaks are called. The AVISynth filter called Despot can do a good job on these, although it is a pain to work with and to set its dozens of setting correctly. RemoveDirt can sometimes remove these.

Here's a link to a similar discussion in this forum:

https://forum.videohelp.com/threads/355084-How-to-remove-Comets-%28Dropouts%29-with-Avisynth

[DB83]

Another option I have found quite effective for comets is a simple Median filter.

[gamjerr]

Thank you - it helps just to have the correct terminology. Yeah despot looks kind of tough to work through. Did try neatvideo demo briefly and it seems to have worked pretty well. I'll keep playing around. I do have the tapes on hand and could try more passes for a median filter, decomet - but it's a lot of video to have in triplicate ~20hrs.

[LMotlow]

Did you know that the frame rate of your sample is 29.96 fps? Utilities report the video as interlaced (if from analog tape, it should be) but the frames look progressive. At the end, the scrolling credits have badly split lines. Are you throwing away fields, or does the tape play that way?

AviSource(vidpath+"sample.avi")
ConvertToYV12(interlaced=false)
RemoveDirtMC(40,false)
Crop(0,0,0,-6).AddBorders(0,2,0,4)

Something more than just a black and white background would be a tougher test.

[gamjerr]

Did you know that the frame rate of your sample is 29.96 fps? Utilities report the video as interlaced (if from analog tape, it should be) but the frames look progressive. At the end, the scrolling credits have badly split lines. Are you throwing away fields, or does the tape play that way?

Oh thanks for that sample run, nice! The clip shows as 29.97 for me and is captured that way - not sure what happened. I did use avidemux to clip this brief sample. I'm not throwing anything away. This is from an old nature doc. Not sure on this particular one, but I know most of these come from BBC (originally PAL broadcasts) and have blended fields when released stateside - maybe that is happening? I'd have to look at the whole doc more.

[LMotlow]

it might not be a problem, but Avisynth and VirtualDub report the frame rate as 97.690 (or "29969/1000"). 29.97 is 30000/1001. Easy enough to fix in Avisynth.