What Avisynth filter should I use for these white flashes?

[StickMonster]

What Avisynth filter should I use for these white flashes?

I tried DeFlicker (http://avisynth.org.ru/deflicker/deflicker.html) with the default settings which definitely helps. It reduces the flash quite a bit, but the result is still too intense. I couldn't figure out any setting to make the deflicker effect stronger. (I played with some setting, but I didn't know what I was doing and couldn't improve the outcome). Any suggestions on some settings or another filter?

By the way, any speculation on what these are or what caused them? The original is on VHSC. I captured them with a Toshiba DVR620 DVD/VHS Recorder, straight to DVD in the unit. I can see the flashes when I just view the tapes on this unit (on a HDTV via HDMI), without trying to record. I don't see flashes like when I play other tapes (commercial VHS tapes).

What's odd is that I don't see these flashes when I play (or capture with a pc capture device) with a different VCR, through a composite connection.

[jagabo]

It could be false Macrovision detection. If so, a Macrovision stripper like the Grex will get rid of it.

You can try some of the flicker removal tools in VirtualDub or AviSynth. One problem you'll have with filtering is the blown out brights. Even if the flicker removal manages to get the overall brightness the same you'll still end up with blown out frames where the details in the brights have disappeared.

[StickMonster]

Thanks for the suggestion. A Macrovision filter would be hardware device, right? Since I am playing and capturing on the same device, I don't see how I could insert one. If I thought it was a macrovision problem, I would return the device. (It's new). These are home movies.

I did wonder if that might be the problem, though. I thought maybe that wasn't the case though, since I see the flashes when playing on the VCR, recording or not, and I don't see the problem with commercial VHS tapes (although I'm not sure if the ones I tried have Macrovision protection or not).

Is there any way to tell more definitively?

And also, I'd still welcome any specific recommendations on filters to try, Avisynth preferred.

[jagabo]

Yes, a Macrovision stipper would have to go between the VHS deck and the DVD recorder.

Macrovision screws with the amplitude of the horizontal sync pulses. Recorders are designed to respond to those signals in variou ways. One is to record over bright and over dark pictures. Sometimes the Macrovision circuitry is over sensitive and responds (partially) to minor variations in the sync pulses, even when Macrovision is not present.

If the DVD recorder has any automatic filters you can control (brightness, contrast, color) try disabling them. Try another VHS deck if you can.

Regarding filtering, try fixing the levels before deflickering. Something like:

Mpeg2Source("TestclipD.d2v", CPU=2)
ColorYUV(cont_y=-37)
SeparateFields()
Deflicker(scene=80, lmin=16, lmax=235)
Weave()

You'll still have problems with blown out brights confusing the deflicker filter.

[StickMonster]

Thanks again for the reply, Jagabo.

I'm trying to make sense of the "ColorYUV(cont_y=-37)" line. Can you explain to me what that does and why it's a good idea? I've read the docs but they're beyond me.

Is that reducing luma by some percentage across the board?

[jagabo]

ColorYUV(cont_y=-37) reduces the contrast. Your video has too much contrast. The brights are too bright and the darks too dark. That brings the levels closer to legal values. That may help Deflicker().