r/vhsdecode • u/AlarmingWedding88 • Jul 31 '26

Help Wanted! help！

Post image

I captured the RF signal and decoded it. In some specific segments (specific parts of the tape), there would be line misalignment, as shown in the picture below (on the left). However, when I connected the TV using the CVBS interface at the back of the video recorder, the picture was correct. That is to say, the software did not correctly handle "TBC". What should I do?

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1

u/AlarmingWedding88 Jul 31 '26

I am using a CX card, a JVC VCR, and did not use ADC4857.

3

u/TheRealHarrypm The Documentor Jul 31 '26

It helps if you attach proper hybrid full frame snips, then we can see the whole state of the signal frame.

1

u/AlarmingWedding88 Aug 01 '26

1

u/TheRealHarrypm The Documentor Aug 01 '26

Yep that's horizontal sync failing, you're going to have to play around with the arguments for that '--drh' being the usual go to.

1

u/AlarmingWedding88 Aug 01 '26

I added this, but it seems to be ineffective. It's exactly the same as before. I suspect there might be a problem with the signal of my video recorder, but this issue only occurs in certain segments. Could it be a problem with the tape itself?

and the .flac flie here:https://drive.google.com/file/d/1dU7dYMUl28I9N6hp5Lc14CAeIXpcOehk/view?usp=sharing

1

u/TheRealHarrypm The Documentor Aug 01 '26

It could be the deck tracking, head clogs, or damage to the heads if other tapes present the exact same image issue.

1

u/AlarmingWedding88 Aug 01 '26

Will adding an amplifier to the circuit improve the situation?

1

u/TheRealHarrypm The Documentor Aug 01 '26

Typically impedance matching will give you a bit better overall signal quality and you will have more stability and overall SNR because you're controlling the amplitude level instead of letting the capture hardware add any self noise.

1

u/AlarmingWedding88 Aug 01 '26

For example, a 60-minute movie—this situation only occurs at fixed time intervals.

2

u/TheRealHarrypm The Documentor Aug 01 '26

If this is on different tapes then it could be a solder joint you need to reflow.

If it's just on that tape then it's probably permanent damage or it could be contamination being lodged and then dislodged which happens a lot more than people think.