Is this classic VHS tape degradation or can it be something else?

[jagabo]

VirtualDub can only detect dropped/inserted frames that it created. If your video came from a device that inserted or deleted frames VirtualDub cannot detect them. The duplicate frames in your earlier video were not created by VirtualDub. You can tell because they are not identical. There is a little noise difference between them.

Regarding VirtualDub for capture, the good thing about it is there are so many configuration options that it can be made to work with just about any capture device. The bad thing about VirtualDub is there there are so many configuration options it can be very hard to get it working with any particular capture device.

[Christina]

This script:

##########################################################################
#
# Abs(v1-v2)
#
# Works for YUY2 and YV12 only
#
##########################################################################

function AbsSubtractY(clip v1, clip v2)
{
    IsYUY2(v1) ? mt_lutxy(v1.ConvertToYV16(), v2.ConvertToYV16(),"x y - abs", chroma="-128").ConvertToYUY2() \
              : mt_lutxy(v1, v2,"x y - abs", chroma="-128")
}

##########################################################################


LWLibavVideoSource("Old JVC Deck Audio Test plus es10 Composite Video clip.avi") 
AssumeTFF()
ConvertToYV12(interlaced=true)
AbsSubtractY(last, last.Trim(1,0))
WriteFileIf(last, "DupFrames.txt", "AverageLuma<1.00", "current_frame", """ " : " """, "AverageLuma", append=false)

Why would the WriteFileIf function return an error on one PC but not another? I was able to run this script on my capture machine, but when I try to run it on my other computer where I do my editing, I get the following error:

Script Error: Invalid arguments to function 'WriteFileIf'.

Edit: Googled it, seems it may have something to do with avs+. I'm reading here: http://forum.doom9.org/showthread.php?t=181657 but I still don't know what I have to do to fix it. Update avs+? I'm afraid to touch anything on this PC because it's been so long since I set it up, I would never remember how to get everything working again if I broke something. Maybe will just stick to running it on the capture PC.

[jagabo]

I don't see anything wrong. That line is exactly the same as the one I posted earlier. Do you have write access to the folder?

[Christina]

I do. It looks like it might be a bug with the version of avs+ I have on that pc.

[Sharc]

If I want to use the audio from one cap and video from another, what tools (besides trial and error) do I use to do that? Do I just try to find the same video frame in each capture in VirtualDub and trim from that point on and then mux in AviSynth?

You could probably open the video1 and audio2 in an editor (NLE) where you can see the video frames and audio waveform on a timeline. Then go to frames like clapping hands or banging doors and shift and possibly stretch/shrink the audio2 to fit the video1. There may be better proposals though, but I don't think one can fully automate the procedure.

[Christina]

Thank you. I’m not sure I’m up for the challenge and my new captures with the non svhs vcr are looking good to me - actually better in a couple of spots probably because of the ES10 this time around. So I think for this tape I’ll just go with using the audio and video from the same capture. I really appreciate all your help on this one!

[jdkessel]

Yes, I used AviSynth:

ColorYUV(off_u=-20, off_v=-40)
ColorYUV(gain_y=70, off_y=-20, cont_u=-100, cont_v=-125)

This was just a crude adjustment to make it look about like the other video. It could be done in one ColorYUV but I centered the U/V channels first (off_u/v), then adjusted the saturation (cont_u/v) and black/white levels.

jagobo I tried this in StaxRip and it was helpful to improve some VHS captures that are very red. I had usually been using the 6-axis color correction filter in VirtualDub to do something similar. I had just been guessing a bit, but I was wondering what you used to come up with the values you came up with for ColorYUV().

Thanks

[jagabo]

Yes, I used AviSynth:

ColorYUV(off_u=-20, off_v=-40)
ColorYUV(gain_y=70, off_y=-20, cont_u=-100, cont_v=-125)

This was just a crude adjustment to make it look about like the other video. It could be done in one ColorYUV but I centered the U/V channels first (off_u/v), then adjusted the saturation (cont_u/v) and black/white levels.

jagobo I tried this in StaxRip and it was helpful to improve some VHS captures that are very red. I had usually been using the 6-axis color correction filter in VirtualDub to do something similar. I had just been guessing a bit, but I was wondering what you used to come up with the values you came up with for ColorYUV().

Thanks

That was quite a while ago but I believe I used Histogram(mode="color2") to match the distribution of colors.