Panasonic EH50 lineTBC not working?
 

I've been capturing with the Pinnacle PCTV USB card (one of the good ATI card clones), and so far I've been happy with the results. However, I've been over those weak signal recordings where image quality was not the most important factor but rather the use of a losslecc video codec.

Then, recently, I got to record good signal (despite some being second-generation copies) where I expected the EH50 lineTBC feature to do its thing. Yet... I'm still getting jagged lines/contours.

Here are the examples. Sorry for the large filesize, but they are the original FFV1 capture files so that all artifacts are shown.

SP recording:
https://drive.google.com/file/d/1ELW...ew?usp=sharing
Attachment 16506

LP recording:
https://drive.google.com/file/d/1LKh...ew?usp=sharing
Attachment 16507

Panasonic EH50 DVD recording:

What I beginning to realize is that captures made with conventional low image sharpness masked the jagged lines of analogic recordings. The ATI clone card is letting me see them...?

The fact that I'm getting the same results with the non-lineTBC Sony RDR-HX710 is making me suspicious and rather depressed. :(

Is it really a malfunction or is it the case of the EH50's lineTBC not being up to standards compared to S-VHS's lineTBC?

It is working as you can see e.g the video under the head switch line has been straightened up. TBCs are never going to be 100% stable though, especially on dubs/slower speed recordings (more so on PAL than NTSC from what I've seen). Also a bit more noticeable on content with some form of pull-down pattern rather than content that was originally interlaced since it's extra noticeable if the video from the 2 adjecent fields don't line up 100%.

It's possible one of the in-vcr TBC/DNRs might be able to do a slightly better job (though they could also do a worse job, hard to know for sure without trying.)

That's really unfortunate. I thought lineTBC could do the trick in other areas other than straight lines. I know it is "line" TBC, but still...

It's just that I've seen some VHS captures online that don't have this issue. They were all NTSC sources, so I guess you were right when you mentioned NTSC captures have fewer issues than PAL captures.

Are there avisynth plugins that can help mitigate this issue in post?

TBCs straighten up the image in general, it's not just straight lines. There is a limit to how perfect they can get it though, especially with 2nd gen tapes. As noted the TBC in a VCR may be able to do a better job but it's impossible to say for sure without trying.

Digital Noise reduction, whether as part of the vcr or in post can sometimes help a bit to calm it a bit.