Horizontal stripes in Video 8 capture with two Panasonic DMRs in line

[ringo1]

Hi!

Proclaimer: I am not talking about the weaving effect of the interlaced material!

These additional stripes only appear if I add a second Panasonic DMR DVD recorder, a DMR-ES10, to my capturing chain. I do this in an attempt to use its highly praised Jitter correction, while I need the second Panasonic DMR, a DMR-EH495, for its HDMI output.

This is a still from the full chain, i.e.
DCR-TRV210E - (S-Video cable) - DMR-ES10 - (Scart adapter) - (S-video cable) - DMR-ES495 - (HDMI cable) - ...:

[Attachment 56568 - Click to enlarge]

This is a still from the chain that does not produce these stripes:
DCR-TRV210E - (S-Video cable) - DMR-ES495 - (HDMI cable) - ...:

[Attachment 56567 - Click to enlarge]

I've also tried different Video cables and scart adapters, but it does not help.

There are certainly various combinations and settings that I haven't tried.
So, is this a well-known phenomenon that has a certain reason?

Cheers and happy new Year!

[oln]

One common issue on Panasonic DVRs (at least the PAL ones) to have capacitors in the power supply that go bad. They often end up looking bulgy with crusty stuff leaking out of the top like this:

[Attachment 56577 - Click to enlarge]

It often causes them to not start at all, but it's possible it could cause image disturbance as well if it's not fully died, they are pretty straight forward to replace if they have gone bad.

On the newer EH57 I have there were some on the digital PCB where the main video processing sits which caused noise in areas with color, though that noise looked more like the artifacts you can get when dealing with composite video. Bad cables can also sometimes cause trouble, though that also looks different (higher frequency) or more commonly the color disappears completely.

Another question, do you actually need the ES10 in between? Most of the time there is very little difference between the jitter correction on the ES10 and the slightly newer models, at least for PAL in my experience, it's only very rarely on very crappy tapes that there is a noticeable difference.

[dellsam34]

This is a common phenomenon related to 8mm camcorders, It has been discussed extensively here, I believe it's an imaging sensor artifact, Your ES495 is just masking it, I came across one customer tape that has it and it was almost eliminated after de-interlacing.

[ringo1]

Very good guess, oln, I just ordered some new capacitors...


[Attachment 56586 - Click to enlarge]

I am not sure that I need the ES10 and I don't want to use it for tapes where jitter isn't a problem with the ES495.
But I wanna have it ready if jitter should be a problem in some tapes... I got about 100 tapes to capture.

If the new capacitors don't help, I'll take a deeper look into your linked thread, dellsam34, though I am a bit scared of the long AviSynth scripts that seemed to solve the problem there.

[oln]

Ah yeah, whether or not the caps are what's causing the stripes issue those will need replacement in any case. The stripes one in your image don't look like they are straight horizontal like the stuff talked about in the thread (which is not related to playback.) The Panasonic DVRs have some noise reduction enabled by default (it's supposed to auto enable/disable if needed depending on the input, so maybe it's only on on the raw input?) so I suppose that could reduce it if active.

[ringo1]

New caps onboard, problem solved:


[Attachment 56675 - Click to enlarge]

At first, I thought it was really caused by the missing NR - I accidently turned it off in both the ES10 and the ER495 - but the still above was taken with NR off as well.
I cannot reproduce these stripes now at all and I've tried 10 variations of cables and settings.

[johnmeyer]

While the caps are clearly bad, I wouldn't have expected that artifact from bad caps. I'll have to remember oln's advice. Good call.

[oln]

Those caps are there to help smooth out the voltage coming from the power supply. If they are bad, the voltage coming out from there will fluctuate up and down a lot more, which can then impact the reference points for the video decoder and encoder ICs.

[johnmeyer]

Those caps are there to help smooth out the voltage coming from the power supply. If they are bad, the voltage coming out from there will fluctuate up and down a lot more, which can then impact the reference points for the video decoder and encoder ICs.

Most of these are switchmode power supplies and when the caps go, the whole thing often just stops. I've repaired quite a few of those.

However, you are right that some of the capacitors are for smoothing the ripple after the high frequency conversion has taken place. Depending on the switching frequency, that residual noise from little or no filtering could indeed cause all sorts of artifacts. Your analysis seems quite good to me.

[oln]

Ah, you probably know more about that than me then. That happened to the EH57 I have, was dead until I replaced the bad caps.