VHS capture, jagged left edge on scanlines, filter for VirtualDub?

[pnauta]

Hi all,

I have my capture setup running, but capturing some low quality VHS tapes off an old JVC recorder. Now everything is ok except the frame shows a jagged vertical edge, and of course all the scan lines are offset likewise. This will be jagged sometimes, but pretty straight most of the time. It's not that the tape is worn or that there is a damaged edge, it's just not very stable.

I'm sure there's a name for this, and possibly a filter to correct it, but I have googled for an hour and giving up. Who can help?

Regards,

P.

[jagabo]

It's called horizontal time base jitter. All analog tape formats suffer from it to some degree. It can't really be fixed (except under some very specific circumstances) after capture. The best way to deal with it is to use an old DVD recorder with a line time base corrector, in pass-through mode, while capturing.

https://forum.videohelp.com/threads/319420-Who-uses-a-DVD-recorder-as-a-line-TBC-and-wh...light=recorder

[orsetto]

To some extent, the severity of this problem depends on the source the VCR was recording from. In my experience, the absolute worst offenders were the bi-directional cable converter boxes of the late 1990s, early 2000s. All the VHS recordings I made from various Pioneer and Scientific Atlanta boxes prior to 2005 are afflicted with a glaringly obvious white jagged sawtooth righthand frame edge. Recordings made on the same VCRs during the same era from my roof antenna have no jagged frame sides at all. VCRs manage to conceal this jagged edge during playback to analog CRT televisions. But when transferred to a PC or DVD recorder, the capture process apparently "zooms out" just enough to make it annoyingly visible.

There are several threads here on VH that provide details on how to crop this jagged side (as well as the more common scan line crud on the bottom edge). The usual cure is to set up some parameters in AVIsynth, VirtualDub etc- run a search of the terms "crop bottom scan lines from VHS" and you should get plenty of hits. Personally, I can't be bothered: I have way too many such recordings, and they aren't important enough for me to do all that post-processing. Unlike the old CRT televisions, most modern flat screen HDTVs have an option to slightly crop the frame edges buried in their picture settings somewhere. I just turn that on, and never see the side jaggies or bottom scan line crap anymore when viewing my digitized VHS.

For tapes you haven't yet captured, jagabo's suggestion to use a DVD recorder passthru sometimes does work wonders to reduce the jaggies. If you also use a higher-end SVHS or DVHS vcr with built-in TBC / DNR features as the playback deck , you can often reduce the jaggies a bit further. Won't be equally effective with every single tape, but can reduce or eliminate the need for software cleanup in some cases. If you want as close to perfection as you can get for every tape, you'll likely need to do software cropping of the video files.

A good list of VCRs with TBC/DNR that can smooth out tape errors can be found at this link. The list starts with NTSC models but if you scroll down the PAL versions are also noted. Of course, all are discontinued so must be bought second hand from eBay or other sources. Such VCRs won't necessarily eliminate the jagged side edge, but they will typically repair the line offset, wiggles and other irritants in the main video area.

[redwudz]

EDIT: Wrong info.

And welcome to our forums.

[JVRaines]

I'm sure there's a name for this, and possibly a filter to correct it, but I have googled for an hour and giving up. Who can help?

Can you post a link to a sample that demonstrates the instability? I am currently working on an AviSynth filter for this problem.