Motion Blur to the rescue!

farss wrote on 4/17/2004, 3:22 PM
I've been converting a wedding video from VHS to DVD and the original video is horrid. Video was probably shot and editied SHVS or VHS but the intro and credits had the level way, way too hot. On a VHS system this causes line tearing on the trailing edges of the high contrast titles. As the titles fade up it gets worse and goes away as they fade down but even without the titles some of the high contrast shots used in the background also suffer. Fortunately the actual video itself is OK, well about as good as it gets for VHS.
I've had a few experts pontificate over it but as the vision has been copied that way there's no way to fix it in the analogue domain.

I was about to give up on this or maybe just do new intros and credits, quite a tedious job. Then I realised the tearing shifts between each frame. So by adding 4 frames of MB across the whole title sequence and keyframing it up to around 10 when the titles are at full brightness, as if by magic the problem is dramatically reduced.

Now the background vision does get a lot of blur during fast pans and zooms but its only a background and as it was shot with a tripod, once the shot becomes static it becomes noticably clearer. Also as I'm only applying a lot of blur when the titles are up the eye isn't watching the background so much anyway. Also they're all wide shots with only trees or flags moving so the MB is totally unnoticable when the shots are static.

Of course this isn't really magic but it does show how useful some of the tools in Vegas are combined with a little lateral thinking.

Comments

Erk wrote on 4/17/2004, 5:27 PM
Thanks for the tips, Farrs. I've been doing some VHS rescue jobs myself, and need to experiment more along these lines to clear some problems up. Thanks for the inspiration.

Greg
farss wrote on 4/17/2004, 6:47 PM
Others had done quite a bit of work on the noise reduction side, do a search through this forum if you're interested.
I'm doing this for money but clients cannot afford to pay for too many hours so I've got to focus on what can be done for X dollars.
Best investment is a TBC unless you've got a VHS machine that has one. I use a ADVC-300 which will also reduce the noise during capture, the DNR in conjunction with 2D NR (read blur) if used carefully also helps.
Grazie wrote on 4/17/2004, 10:55 PM
farss, do you remember some months back a post regarding the "wobble" on the horizontal lines in an Excel spreadsheet prsentation? I know it really the exact same problem, but using a tiny bit of blur got it to go . . but then ADDING a bit of sharpness brings back . . .well the sharpness - if you want to have a tiny bit more control. The effect of using this two was quite amazing.

Grazie
farss wrote on 4/17/2004, 11:08 PM
Grazie,
the trick here was motion blur which causes frame averaging. In your case normal gaussian blur would fatten the line and then the unsharpen mask should give it a hard edge. By making the line fatter you'd avoid the interlace jitter.

My trick didn't make the problem go away, there's still something there but instead of horrible artifacts there's just a smudge.
Grazie wrote on 4/17/2004, 11:10 PM
Oh yeah! Understood! - G