Fixing QTGMC field bounce?

[Brassplyer]

Is anyone familiar with the phenomenon of QTGMC creating frames that are off by a scan line at settings slower than "Fast"? Causes a "bounce" of the frames when scrolling for example in Virtualdub.

Anyone know if there's a fix for it?

[hello_hello]

If it's the same source you were asking about at VideoHelp, I think it's the source, not QTGMC that's to blame.

Try this:
SeparateFields()
Spline36Resize(720,480)

That doesn't look like normal interlaced video to me. The picture isn't moving up and down when you step through it. The noise does, but not so much the picture. It's like it's already off by one scan line. I don't know how it ended up the way it is, and maybe someone else will have a better idea, but even though it's all wrong, the following produces a fairly stable picture. It's only 29.970fps progressive though.

a=separatefields().nnedi3(dh=true).SelectEven()
b=separatefields().nnedi3(dh=true).Selectodd()
Merge(a,b).QTGMC(InputType=1, EzDenoise=3).LSFmod()

I assume you're still talking out the video here (http://forum.videohelp.com/threads/381887-Particular-vid-looks-worse-Blu-Ray-to-HDTV-than-on-computer-monitor?highlight=bounce)?

[Brassplyer]

If it's the same source you were asking about at VideoHelp, I think it's the source, not QTGMC that's to blame.

I assume you're still talking out the video here (http://forum.videohelp.com/threads/381887-Particular-vid-looks-worse-Blu-Ray-to-HDTV-than-on-computer-monitor?highlight=bounce)?
I've seen it numerous times before with other video taken directly off a DVD. I just always figured that's the way QTGMC worked but Jagabo observed it to be abnormal and pointed out it only happens on settings slower than "Fast". I never use the faster settings which I'm sure is why I previously didn't notice it doesn't happen with those settings.

Try QTGMC on any DVD video you think is "correct" interlaced video with a setting like "Slower" without any fix script and see if it happens.

[ndjamena]

separatefields().nnedi3(dh=true)
Merge(selecteven,selectodd)).QTGMC(InputType=1, EzDenoise=3).LSFmod()

[Brassplyer]

separatefields().nnedi3(dh=true)
Merge(selecteven,selectodd)).QTGMC(InputType=1, EzDenoise=3).LSFmod()
Isn't something like this bypassing QTGMC's deinterlacing?

[ndjamena]

Yes, that's the point. It's endless greetings script, I just modified it because I didn't see the point of creating two separate instances of NNEDI3 when one would do.

[hello_hello]

Endless Greetings?

Brassplyer,
I don't use QTGMC for de-interlacing much these days (I use it regularly in progressive mode for denoising) but I've rarely seen the bouncing problem. Maybe I'm monumentally unobservant, but here's links to a few sample QTGMC encodes. They were created to compare QTGMC with Yadif at the time. The original DVD/mpeg2 video is also attached if you want to try encoding them yourself.

http://forum.videohelp.com/threads/354092-Converting-video-frame-rates?p=2225116&viewfull=1#post2225116
http://forum.videohelp.com/threads/354092-Converting-video-frame-rates?p=2225237&viewfull=1#post2225237

[ndjamena]

I feel stupid after the first hello.

[hello_hello]

If you do unholy things to your sample before de-interlacing you can prevent QTGMC from causing a bouncing effect, but the end result of this script is effectively progressive video (when applied to your sample), hence adding SelectEven(). If you did this to "normal" interlaced video though, you'd no doubt make a mess, but maybe it helps prove it's not QTGMC's deinterlacing at fault. The output of this script doesn't look all that much different to the first one I posted.

SeparateFields()
Spline36Resize(720,288)
nnedi3(dh=true)
AssumeFieldBased()
weave()
Spline36Resize(720,480)
QTGMC(EzDenoise=3)
SelectEven()
LSFMod() # possibly a waste of time.

[Brassplyer]

maybe it helps prove it's not QTGMC's deinterlacing at fault.
Are you not able to reproduce the issue I've described with other video?

What are you classifying as "normal" interlaced video?

The sample I put up is straight off a DVD, albeit not a commercial DVD.

[hello_hello]

Are you not able to reproduce the issue I've described with other video?

Almost never.

What are you classifying as "normal" interlaced video?

Just standard interlaced DVD video such as the samples I linked to.

The sample I put up is straight off a DVD, albeit not a commercial DVD.

Yeah and I think it's had all sorts of horrors inflicted on it at some stage, such as incorrect resizing.

Try the small samples I linked to and see if the same thing happens. I very much doubt it will.