|
|
| TCmullet |
| Posted: Jul 26 2011, 10:50 PM |
 |
|
Advanced Member
Group: Members
Posts: 312
Member No.: 3970
Joined: 2-May 03
|
I found this 7 year old post on another forum:
"I have heard that there is a plug-in for one of the freeware applications that attempts to do line-by-line correction of horizontal displacement. (Sort of an after-the-fact timebase correction function). But it certainly involves a lot more fooling around than using a conventional hardware TBC. And of course it can only deal with the video that was captured with the non-tracking digitizer hardware, so it doesn't have the original sync pulses as a reference point. It has to guess from the video whether there is a timebase error for each specific line."
I'd like to guess he's referring to a VD filter. Anyone know of what he speaks? I have an important home-made DVD made from a poorly captured VHS tape, with lots of shimmering skew from line to line. Makes vertical lines such as telephone poles look like they're quivering with fright. I would think a filter like this wouldn't be too hard to create by someone intimate with how to write a filter.
Algorithm:
For all lines but the first, do a series of test shifts, shift -5 pixels, then -4, all the way up to +5. For each shifting subtract the luminance of each pixel from the corresponding luminance of the corr. pixel of previous line. Sum the differences for all pixels within this shifting, then of the 11 shiftings, the one with the least sum of differences is the one to use for permanently shifting that line. Perhaps instead of shifting each line immediately, one should make a first pass of all the lines to find the nominal reference point, then go back and do the permanent shifts of all lines to that reference point. I would think interlaced video would not be a factor; its should work for interlaced without any special considerations.
Seems simple enough, so I'm wondering if someone has done it. I could really use it. I did try searching around, but if it's there, I couldn't pick the right search terms.
|
|
| -vdub- |
| Posted: Jul 27 2011, 09:09 PM |
|
|
Advanced Member
Group: Members
Posts: 613
Member No.: 27087
Joined: 24-February 10
|
re: http://www.tomshardware.co.uk/forum/144308...ased-correctors
Is there a list that compares all today current tbc devices for sale and also has list (if any) software tbc ?
Doesn't the same company mentioned in url (avermedia) and other companies that make tbc capable devices. Have now tbc in many cheaper digital products that works the same as the older expensive models had done.
Recent pc and gfx should easily achieve tbc through software, but had anyone written a tbc in software that is comparable to a good hardware tbc ? |
|
| TCmullet |
| Posted: Jul 28 2011, 12:25 PM |
|
|
Advanced Member
Group: Members
Posts: 312
Member No.: 3970
Joined: 2-May 03
|
Hey "-vdub-",
I think you're confusing the issue. That link (which takes you to where I found what I quoted) is talking about real-time TBC operation. Of course that is the ideal. But I don't have a Delorean time machine to go back in time and space to when/where the tape existed and re-capture it. I'm stuck with this DVD of time-based jitters. (And from looking at other artifacts, I suspect it was an EP tape, not SP. Further "drat".) My solution (obviously) can't be in and doesn't need to be in real time; it's a post-processing task.
Perhaps you're simply looking for real-time TBCs. But I'm looking for a Vdub or AviSynth filter that cleans up the horizontal jitters in each digital frame in my AVI. There are other clean-up things I must try to do, but this jitters thing is the worst problem. |
|
| -vdub- |
| Posted: Jul 29 2011, 01:23 AM |
|
|
Advanced Member
Group: Members
Posts: 613
Member No.: 27087
Joined: 24-February 10
|
No problem i only searched for your quote and went from there. Thinking it would be good to have as a plugin with capabilities and tech that exist in newer pc.
Maybe someone thinking the same as you, have also some further ideas. Uploading a video clip of the problem, that can be used for testing. Then maybe now or future someone see this post and knows of, or has written a solution that can correct your clip. |
|
| TCmullet |
| Posted: Jul 31 2011, 01:39 PM |
|
|
Advanced Member
Group: Members
Posts: 312
Member No.: 3970
Joined: 2-May 03
|
fccHandler, I tried to p.m. this to you, but your "box is full", so I'm writing it here.
Have you seen my thread about Software Time Base Correction? If so, I'm surprised that noone (including you) knows of a filter IF one has been written. Based on the algorithm I described there, do you think it's feasible?
The guy there suggested I upload a few frames. I'd like to, but I can't figure out any way to upload (or attach) ANYTHING. The "IMG" button doesn't seem to do anything. Didn't there used to be file-attachment capability on this forum?
Also, I found it hard to find the way to p.m. someone (you). Had to find where you had posted a recent comment (which wasn't hard).
(And now I find the p.m. to you won't work as your box is full.) |
|
