Help please with the video

[Dremon]

Hello everyone!!

I am moving my camcorder videos to DVDs. The usual process I use is:
- bob the source to 50p (or in case of bad lighting to 25p),
- deshake it (using Gunnar's VB plugin: BTW is it still better than DePan??),
- NLE,
- clean, reinterlace and encode back to MPEG2.

This video was shot in low light therefore it makes sense to just
DoubleWeave().SelectOdd() to get 25p. It was deshaked, edited and then... I have forgot to remove reinterlacing :eek:SeparateFields().SelectEvery(4,0,3).Weave().AssumeTFF() from the script. The result of compressing to progressive MPEG2 is attached. Sample (http://www.mediafire.com/?zymmztmowwn)

Now, I have lost my originals so I am desperate to fix the file somehow. Does anyone have a good suggestion?


EDIT: This is my first post so I say HELLO EVERYONE!!! I have been lurking since 2007 learning a lot and I really appreciated the work the this community puts into AviSynth and all the plugins!! Keep up great work!

[Alex_ander]

This video was shot in low light therefore it makes sense to just
DoubleWeave().SelectOdd() to get 25p.

Those lines only change field order in an interlaced video or add field-shift interlacing to progressive. Was it what you wanted?

[2Bdecided]

Fascinating, in a tragic way.

As Alex_ander said, you didn't deinterlace at all. You fed interlaced material into VirtualDub. DeShaker has wrecked the interlacing - merging fields in some places, and swapping field order - but (uniquely, because I guess you enabled the rotation and zoom correction in deshaker) it's managed to give you different field order in different parts of the same frame! So there's no longer any "correct" field order to replay this - even on a single frame-by-frame basis - whichever field order you choose, some parts of the frame will move forwards while others move backwards, giving a very strange shaking look to it all.

The best you can do now is blur away the interlacing lines. Try a simple
blur(0,1.0)
sharpen(0,0.5)
or some slightly cleverer way of doing the same thing which someone will post next...! ;)

This will give 25p. You can then motion interpolate to 50p using mvtools (then interlace to 50i), but it's probably not worth it.

Now, I have lost my originals:( No tapes? No DV-AVI files?

Apart from anything else, I'm amazed anyone trusts Deshaker enough to destroy whatever they had before Deshaker.

Cheers,
David.

[Dremon]

Those lines only change field order in an interlaced video or add field-shift interlacing to progressive. Was it what you wanted?
In a low light situation my camcorder records at 25p but still encodes the file as 50i mpeg2 file. When I use a simple bob then I get 50p with every second frame identical to the previous one.
Instead of bobbing I use DoubleWeave (http://avisynth.org/mediawiki/DoubleWeave) which combines the fields together (fld0&1-> fr0, fld1&2->fr1, etc). After this I just SelectOdd required frames. The end result is removal the artificial interlacing - I get 25p video. I believe this is what you call "field-shift interlacing" :)


As Alex_ander said, you didn't deinterlace at all. You fed interlaced material into VirtualDub. DeShaker has wrecked the interlacing - merging fields in some places, and swapping field order - but (uniquely, because I guess you enabled the rotation and zoom correction in deshaker) it's managed to give you different field order in different parts of the same frame! So there's no longer any "correct" field order to replay this - even on a single frame-by-frame basis - whichever field order you choose, some parts of the frame will move forwards while others move backwards, giving a very strange shaking look to it all.

Yes, that could be it. I forgot to put DoubleWeave().SelectOdd() in the AVS script which I fed to DeShaker... :confused:

Apart from anything else, I'm amazed anyone trusts Deshaker enough to destroy whatever they had before Deshaker.
I usually only delete sources (MPEG2 from HDD camcorder) after I verify correctness of the encodes. I simply deleted the originals by accident before I verified the results. It is actually one of three broken videos but I still have the originals for the remaining two of them.

I have good experience with Deshaker (well, it has its issues) but I can see your point about zoom and rotation. These are not very useful so I will probably switch them off for next encodes.

[2Bdecided]

I think zoom and rotation can be useful (though they look very strange when they erroneously "correct" something that's not wrong!) - they just happened to enable the almost unique destruction of the interlacing you have here.

Whether they're very useful depends on your filming style. I've need them both - especially when my wife has used the camcorder! ;)


As for 25p in 50i - you shouldn't need to do anything clever to it in AVIsynth - no deinterlacing, no re-interlacing - unless you're trying to match the frame rate of your bobbed 50i>50p clips to process them all together? Which isn't a good idea when you're going to deshake them. They should be processed as-is: 25p. The fact they're "-in-50i" in the MPEG-2 is almost irrelevant inside AVIsynth.

Hope this helps.

Cheers,
David.

[Alex_ander]

In a low light situation my camcorder records at 25p but still encodes the file as 50i mpeg2 file. When I use a simple bob then I get 50p with every second frame identical to the previous one.
Instead of bobbing I use DoubleWeave (http://avisynth.org/mediawiki/DoubleWeave) which combines the fields together (fld0&1-> fr0, fld1&2->fr1, etc). After this I just SelectOdd required frames. The end result is removal the artificial interlacing - I get 25p video. I believe this is what you call "field-shift interlacing" :)

Then you really wanted it :) . In case (which I didn't mention) a progressive video is (artificially) interlaced by field-shift, those lines correct it by shifting fields towards their native frames. I suggested it in an older thread as the shortest script for that task.

P.S. I think that if the video was really shot as 25p and field-shifted afterwards, then packing fields back into progressive frames must preceed deshaking. In case of 50i I'd try to use a single-field based bob filter (like nnedi etc.) before deshaking.

[Dremon]

I've need them both - especially when my wife has used the camcorder!
Yes, I know it from my personal experience too :) But even in this extreme ;) case H and V deshaking are most useful.

As for 25p in 50i - I need to convert it to progressive to be able to use HDRAGC.
In general dealing with a video that can change from 25p to 50i many times is not easy. For videos with a lot of "real" 50i content I often convert 25p parts using DoubleWeave.SelectOdd and then double fps to 50 using MVTools - this gives me an ok quality for the whole movie.

The biggest challenge are of course videos with 25p and 50i changing frequently inside one piece. It was already briefly discussed here on the forums some time ago and the conclusion was there is no automatic way to correct this.
When dealing with this kind of file I just use a bobber and feed it into deshaker - it's not the best approach but it's a fast one :)

Then you really wanted it. In case (which I didn't mention) a progressive video is (artificially) interlaced by field-shift, those lines correct it by shifting fields towards their native frames. I suggested it in an older thread as the shortest script for that task.
Yes, I wanted it but I think I forgot to shift the frames and fed 50i stream into deshaker as a progressive video which caused this interesting effect. The problem is that Windows MPG decoder hid those lines and the video looked ok on my computer. It was only on big TV where I noticed it first. I am more careful now and check on target display to make a final verification :cool:

In case of 50i I'd try to use a single-field based bob filter (like nnedi etc.) before deshaking.
Would it give better quality? If you took a real 25p video, separated fields and wanted to get it back to 25p, would you use nnedi?