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Old 17th March 2023, 20:49   #21  |  Link
Selur
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an you get to their site at all by just going to the main page?

https://www.tgrantphoto.com
nope.

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You could try a VPN, if you have one installed.
Works with VPN/WebProxy.
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Old 17th March 2023, 20:49   #22  |  Link
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My gut says that sounds like too many combinations for that type of approach
Yes. I will keep trying...

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If SS already had a look at the combinations and couldn't come up with something more accurate, I doubt it's possible in avs
The original script was developed for another kind of defect (corrupted field): https://forum.doom9.org/showthread.php?t=183582. I modified it for the field shift problem.
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Old 19th March 2023, 10:48   #23  |  Link
robert.n
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Originally Posted by johnmeyer View Post
Time base correction is not well understood by most people. (...)
Great post, thank you! This helped connect a lot of dots for me regarding TBC.

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On paper, the problem seems simple enough to solve especially if you are lucky enough to have a capture which has not been cropped in any way and therefore includes pure black down either the left or right edge of the frame. The idea is that you shift each line so that you get a "clean edge" up and down the extreme left or right of the frame.

However, while I think the problem is solvable, it requires some reasonably advanced programming skills.
This is exactly the method that is implemented in vhs-deshaker. The pure black on the left-hand and right-hand borders of the frames is used to re-align/unshift all rows of the frames. This can fix mild to medium instances of horizontal shaking/distortions caused by lack of TBC.
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Old 7th April 2023, 12:02   #24  |  Link
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Today I greatly improved the "How does it work" description of vhs-deshaker, including visualizations of what happens. You can read it here if you're interested: https://github.com/rsnitsch/vhs-desh...-deshaker-work
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Old 3rd May 2023, 00:55   #25  |  Link
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For those who might not find it, if you click on Robert.n's link in post #5, and then click on the Readme.md file and you'll get lots of good information on his software, along with an excellent before/after video.

It looks to me like the software works on the entire frame rather than on individual lines. It therefore will probably not be useful for TBC errors which change a vertical flag pole into a wavy mess.

Since this is correcting time base errors, it is worth mentioning past efforts on this problem. Building a software TBC has been a holy grail in this forum for many years, and while a few authors have come close, no one has ever produced something that really works, at least as far as I know. Here are links to some previous attempts. The length of some of these threads clearly shows the interest in such a project:

New Script: Software TBC 0.6 & Sample (was Fast Line Shifter 0.53)

Software TBC (Multi-page thread 1 2 3 4)

Could a software equivalent to TBC be done in Avisynth... (Multi-page thread 1 2)

However, even if this software isn't developed any further, it looks like it will still be very useful for certain types of VHS capture problems.
Wow, I can't believe this thread is being updated now! Thanks John Meyer! I spent half my inheritance in the 90s (my last parent died in '91) on expensive VHS/S-VHS video equipment. Most is gone now. But after 20 years of many tapes (over 1000) staying safely in storage, I'm embarking now on selectively digitizing them. I've hunted but not found a cheap hardware TBC. I owned (let me count) at one time, 5 units, but over the course of that decade had experience with 7. Panasonic AG-7750 (broadcast quality) had an excellent one. My 2 AG-1970s had TERRIBLE ones, which I realized no one should use. Hotronic outboard monster; terrible in several ways. Two GVP Amiga based cards, which did a good job but were not neutral-based in their procamp controls. (We don't need procamp controls; we have "Tweak".) I still have the GVPs but don't know if they can be hooked into a PC and whether there is PC software to control them. Heck, I just want ONE! (I'm not doing 2 camera shoots of anything; really no shoots of anything!)

But yes, having been a programmer from college freshman days (1972) till gradually having to drop out roughly 20 years ago, and having started using Avisynth occasionally since about 2004 (best I can estimate), I HAVE wondered why software can't be written. I will eagerly devour the links you all have given EXCEPT for deshaker type info. (EDIT: Oops, I realize I may need to jump on the deshaker tool.)

The most common problem does not need VERTICAL correction, as a decent tape in a machine with a good video head will not need that. It's the individual LINES that need it. I'm 69.5 and in middle of battling stage 4 melanoma, as well as being a very low-income senior. After the melanoma's over (and I am encouraged at the probabilities it won't be over via the grave), I may be able to devote some time and brain to programming IF I had access to knowledge. My skills in Avisynth are relatively weak. I'm about to buy a $100+ price range SD to HDMI upscaler. I doubt even those more expensive units have a TBC in them. (Don't buy $50 and under units.) Again, mainly JohnMeyer and Robert.N, thanks for bringing up this subject just a MONTH or so before I needed to jump into the fray! I want a solution BEFORE I do any serious captures. (I do have at least one VCR head to replace first.)

Last edited by TCmullet; 3rd May 2023 at 03:02.
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Old 3rd May 2023, 03:28   #26  |  Link
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Originally Posted by robert.n View Post
Great post, thank you! This helped connect a lot of dots for me regarding TBC.
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Originally Posted by johnmeyer View Post
On paper, the problem seems simple enough to solve especially if you are lucky enough to have a capture which has not been cropped in any way and therefore includes pure black down either the left or right edge of the frame. The idea is that you shift each line so that you get a "clean edge" up and down the extreme left or right of the frame.

However, while I think the problem is solvable, it requires some reasonably advanced programming skills.
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This is exactly the method that is implemented in vhs-deshaker. The pure black on the left-hand and right-hand borders of the frames is used to re-align/unshift all rows of the frames. This can fix mild to medium instances of horizontal shaking/distortions caused by lack of TBC.
For YEARS, I've visualized in my head that THIS is exactly how the problem is solved. When you look at a frame of video in any video editor (VirtualDub, AviDemux, etc.) you see the beginnings of lines in the left black border as not being lined up. I did not think of the right border as I figured the timing was being lost at tape playback time between lines, leaving HSync pulses not at the right times. But yes, it makes sense that even after you line up the lines at the left edge, the right edge might be somewhat jagged due to drift between the start and end of a line. I'd LOVE to try this, as it sounds like with most video it should work! (I thought any "deshaker" is dealing with camera shake, not timebased errors.) But I'm scared of going outside the realm of running an Avisynth script. Let me study some more and I may ask you questions, Robert.
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Old 3rd May 2023, 03:37   #27  |  Link
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Today I greatly improved the "How does it work" description of vhs-deshaker, including visualizations of what happens. You can read it here if you're interested: https://github.com/rsnitsch/vhs-desh...-deshaker-work
Robert, though I was considered a very good programmer from my first job in 1978 thru about 1991, I have NEVER been able to acquire a Windows .exe file from that place called Github. I've always been very intimidated by the zillion buttons with no explanations of anything there. Could you please walk me through getting your Windows executable?? (Or anyone?) I do not want to compile; I do not want (or have the ability at present) to set up a development environment of any kind except Notepad for editing Avisynth scripts to feed into the last version of VirtualDub obtainable before "Phaeron" brought the Vdub forum totally down years ago. Just need to know how to get the .EXE. I'll let you all know how the tool performs for me.

EDIT: OOPS!!! Just after I sent the link to a local programmer friend, I happened to notice in the lower right region that "Releases, Latest" region. The joke's been on me all these years! (I'm so used to normal webpages where it's generally easy to download an application by a non-programmer.)

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Old 3rd May 2023, 04:25   #28  |  Link
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Robert, I will be using Avisynth for everything except the direct running of vhs-shaker.exe. What are the rules for what codecs I can use when I create my input.avi? Does it have to be an AVI or can it be something else like an MP4? Am not worried about audio. I can fix all that after the video is done. I do wonder though why you're not using VFW so that I can pick an output codec in VirtualDub to read it later.

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Old 3rd May 2023, 11:15   #29  |  Link
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What are the rules for what codecs I can use when I create my input.avi?
Internally vhs-deshaker relies on OpenCV's VideoCapture feature, which in turn is based on ffmpeg (among others). Therefore, vhs-deshaker supports a wide variety of input codecs/formats. As a rule of thumb: If ffmpeg can process it, then vhs-deshaker can likely open it, too.
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Old 3rd May 2023, 12:42   #30  |  Link
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Yep, found that out. It easily processed my mp4 TS that my capture card had created. Now to figure out why it's working terribly. I have an idea; will report back after further testing.
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Old 14th May 2023, 00:43   #31  |  Link
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My first test was pretty bad. Much jerking around left to right and back. After staring at it a minute, I concluded the noise bar at the bottom was about as far offset as was the sideways jumping. I concluded that I'd need to strip that off.

The sad news was that after stripping it off, the jerking was almost as bad. So there's something incompatible between your program and my videos. I have to give up on this for now. I can't think of anything else to fix it. Note: My video is not bad in need of correction. I had thought that the very slight fast jitter I see in some spots made me think this was the problem in this case.
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