Yadif-like deinterlacing option?

superduck

New member
Hello, I'm probably getting some terminology wrong here but I'm capturing VHS tapes as an interlaced 25fps video (is that also known as 50i ?) and currently using ffmpeg yadif=1 to convert that into a progressive 50fps before importing it into videredo 6 to cut it up. I've not been able to find a deinterlacing option in videoredo that gives me the same result, is it possible? The system I have works but it would be more convenient if I could do everything inside videoredo. Hope that makes sense!
 

Dan203

Senior Developer
Staff member
The "Smart" deinterlace option in VRD is probably the closest to yadif we offer.
 

musicvid

Member
Hello, I'm probably getting some terminology wrong here but I'm capturing VHS tapes as an interlaced 25fps video (is that also known as 50i ?) and currently using ffmpeg yadif=1 to convert that into a progressive 50fps before importing it into videredo 6 to cut it up. I've not been able to find a deinterlacing option in videoredo that gives me the same result, is it possible? The system I have works but it would be more convenient if I could do everything inside videoredo. Hope that makes sense!
You are describing "BOB," otherwise known as Frame Doubling with Yadif 2X.
VideoRedo uses the same deinterlacer developed by the inventor of BOB, whose name is Donald Graft.
Unfortunately, I cannot get 50 interpolated fps with BOB selected, no matter which frame rate I choose.
Perhaps a developer can look at this and show us how it's done properly inside VRD.
 
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superduck

New member
The "Smart" deinterlace option in VRD is probably the closest to yadif we offer.
Thanks, Is it possible to get a 50fps video in VRD too with this method? When I select 50fps I just get a 50fps file that plays at 25fps (1 new frame every 2 frames). Have attached a screenshot of my current settings if you could advise please?
 

Attachments

musicvid

Member
Superduck, these are the settings I tried yesterday, which seemed the most logical (uses the BOB filter), but unfortunately they did not work.
BOB.jpg
 
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Dan203

Senior Developer
Staff member
Thanks, Is it possible to get a 50fps video in VRD too with this method? When I select 50fps I just get a 50fps file that plays at 25fps (1 new frame every 2 frames). Have attached a screenshot of my current settings if you could advise please?
No, we don't do frame interpolation. When you increase the frame rate we simply repeat every frame.
 

musicvid

Member
The BOB option in the Donald Graft Deinterlacer is designed to do exactly this, and it works in VDub. If it is not a functional setting in VRD, maybe better to just eliminate it?
 

Dan203

Senior Developer
Staff member
The BOB option in the Donald Graft Deinterlacer is designed to do exactly this, and it works in VDub. If it is not a functional setting in VRD, maybe better to just eliminate it?
BOB is a generic term. We don’t use the "donald graft deinterlacer".

 
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musicvid

Member
BOB is a generic term. We don’t use the "donald graft deinterlacer".
Respectfully, I must defer to my experience here. BOB is a term coined by Donald Graft to define line doubling to achieve a progressive frame rate that equals the field rate of the interlaced video source, just as your link states. I was there when it was introduced as a VirtualDub filter in about 1999, iirc. Yes, I go back that far.

On Nov. 16, 2021, in response to my question, DanR said,
We use Decomb licensed from Donald Graft with some internal speed improvements. I started looking at YADIF, but it didn't work well for I-frame seeking. It would probably be OK to use in the output stage.
The thread is here: https://www.videoredo.net/msgBoard/...using-for-smart-deinterlace.37797/post-135085
My own tests are farther down in that same thread.

I can confirm that the BOB option, which is available in the dropdown menu in VRD 6, is nonfunctional. I wish it was active; thanks once again for considering our suggestion.
 
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Dan203

Senior Developer
Staff member
Respectfully, I must defer to my experience here. BOB is a term coined by Donald Graft to define line doubling to achieve a progressive frame rate that equals the field rate of the interlaced video source, just as your link states. I was there when it was introduced as a VirtualDub filter in about 1999, iirc. Yes, I go back that far.

On Nov. 16, 2021, in response to my question, DanR said,

The thread is here: https://www.videoredo.net/msgBoard/...using-for-smart-deinterlace.37797/post-135085
My own tests are farther down in that same thread.

I can confirm that the BOB option, which is available in the dropdown menu in VRD 6, is nonfunctional. I wish it was active; thanks once again for considering our suggestion.
To be honest this is more DanR's area than mine, so I talked to him about it and did some testing and it turns out making BOB work is a bit more complicated that it probably should be. So what you have to do is both set deinterlacing to BOB and manually set the frame rate to 2x the source framerate. Automatic does NOT work here. (it probably should) If you do that then the output has proper BOB deinterlacing. If you don't set the frame rate to 2x manually then it just uses "smart" deinterlacing instead and keeps the source framerate.

As for how BOB works, it's just duplicating fields so it's not complicated, no special algorithm is needed. In encoded video interlaced files are stored as field pairs to make a complete frame. You just have to pop those out and then copy the fields up or down, depending on if they're odd or even, to make two complete frames. We only use Donald's code for the "smart" deinterlacer, because that is complicated.
 

musicvid

Member
Thank you for your direct reply.
As far as setting mode to BOB and setting frame rate to double, that is what I believe I did above, since VDub (DG) and Handbrake (Yadif) use the same scheme. I'll test again, but I believe I got no frame interpolation, only doubling, having it set like this with 25i FHD source.
BOB.jpg

I will confirm the test again in the next couple of days.
 

Dan203

Senior Developer
Staff member
Thank you for your direct reply.
As far as setting mode to BOB and setting frame rate to double, that is what I believe I did above, since VDub (DG) and Handbrake (Yadif) use the same scheme. I'll test again, but I believe I got no frame interpolation, only doubling, having it set like this with 25i FHD source.
View attachment 3400

I will confirm the test again in the next couple of days.
Just to be clear, there is no interpolation. All BOB does is separate the odd and even fields into their own frames, then it duplicates those fields up/down to fill in tne gaps.

None of the deinterlace settings in VRD do interpolation.
 

musicvid

Member
@Dan203
After repeating my test with controlled 29.97i source I can now confirm that BOB deinterlace appears to be working correctly In VRD. Good news for @superduck , set your options like this and it should work with true 25i source.
BOB.jpg
I apologize for basing a conclusion on my quick test, without having caught all the variables.
I had inadvertently used telecined broadcast source for my test farther above, and of course it was messing with the results.

So now I'm going to start using BOB for some broadcast conversions, and see how it looks.
For anyone interested, I have zipped my good 29.97i test source, and VRD examples of SMART 30p and BOB 60p for comparison. I haven't tested Weave yet, but I may if the need arises.

30Svs60B copy.jpg
 
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