JVC HR-S7955 VCR playing back too fast?

[hole]

Hello, I'm trying to capture some VHS tapes with a blackmagic intensity shuttle.
I have a JVC HR-S7955 which has s-video out
and a JVC HR-J785 and JVC HR-S9675

All of them drop the signal to the Intensity shuttle but work fine to a TV.
I'm guessing I need a TBC? which ones are recommended for someone in the UK?

my main issue is the JVC HR-S7955 playing back fast.

I can play some VHS tapes of TV recordings but VHS tapes that were recorded on a camcorder and then onto a VHS playback high pitched and fast, any idea why this is happening?

I've tried turning the different settings off on the player and pressing all the buttons on the remote but nothing seems to slow down playback

[lordsmurf]

You have two very separate issues here.

1. BM card drops, infamous for it.
2. Speed issues.

Blackmagic cards drop frames, even with TBCs in use. This is well known for these cards, to the extent that even BM support warns folks away from using their cards for VHS work. The SD ingest was an "also does" afterthought feature that doesn't work correctly. It's an excellent HD card, for HD sources. Not SD.

It will balk at TBC(ish) devices, actual TBC required.

The speed problem could be do to many variables, not sure where to start. Are you perhaps using OBS for capture -- a program that is NOT suggested for that tasks, as it's digital stream recording software, not analog capturing software. And no, the fact that OBS "sees' the card does not matter. It screen records from a display layer, not capture direct from the card output.

[hole]

Quote:

Originally Posted by lordsmurf

You have two very separate issues here.

1. BM card drops, infamous for it.
2. Speed issues.

Blackmagic cards drop frames, even with TBCs in use. This is well known for these cards, to the extent that even BM support warns folks away from using their cards for VHS work. The SD ingest was an "also does" afterthought feature that doesn't work correctly. It's an excellent HD card, for HD sources. Not SD.

It will balk at TBC(ish) devices, actual TBC required.

I got the BM because I thought it would be my best option for s-video capture from camcorders and VHS. what would be a better option? going for highquality capture that I can edit in prem.

I was looking to get a TBC device but is that just a waste of money if in the end the BM is going to be a bad option?

Quote:

Originally Posted by lordsmurf

The speed problem could be do to many variables, not sure where to start. Are you perhaps using OBS for capture -- a program that is NOT suggested for that tasks, as it's digital stream recording software, not analog capturing software. And no, the fact that OBS "sees' the card does not matter. It screen records from a display layer, not capture direct from the card output.

I'm using Blackmagic Media Express to capture video with the BM intensity shuttle. It seems to do a good job of recording and de-interlacing (unless thats what prem pro is doing but still I'm happy with the BM capture when its not dropping out)

The playback speed issue is happening when I connect the VCR into a sony crt trinitron TV. TV recordings playback fine but the camcorder tapes don't. so it IS the VCR. I can play the SAME tape on one of the other two VCRs I have and they play fine but they don't have s-vdieo putout. I can get them to playback "right" by turning the jog wheel and playing back in slowmo but thats causes other issues and is not fixing the issue

-- merged --

Here is one of my home movies playing in the S-video VCR FAST and the other VCR at normal speed

JVC HR-S7955 playing back fast

JVC HR-J785 normal playback

any idea how to slow down the JVC HR-S7955

[lordsmurf]

Quote:

Originally Posted by hole

I got the BM because I thought it would be my best option for s-video capture

Lots of people make that same mistake, the issue is al over the web, even the BM site.

Quote:

what would be a better option? going for highquality capture that I can edit in prem.

Better card.

Quote:

I was looking to get a TBC device but is that just a waste of money if in the end the BM is going to be a bad option?

No, because all cards will need some form of TBC. You've already seen what happens when you try to do without.

Quote:

I'm using Blackmagic Media Express to capture video with the BM intensity shuttle. It seems to do a good job of recording and de-interlacing (unless thats what prem pro is doing but still I'm happy with the BM capture when its not dropping out)

The software does not matter.
Never deinterlace during capture.
But it's not doing a "good job" here whatsoever.

Quote:

The playback speed issue is happening when I connect the VCR into a sony crt trinitron TV. TV recordings playback fine but the camcorder tapes don't. so it IS the VCR. I can play the SAME tape on one of the other two VCRs I have and they play fine but they don't have s-vdieo putout. I can get them to playback "right" by turning the jog wheel and playing back in slowmo but thats causes other issues and is not fixing the issue

You have some sort of tape speed recording issue, or PAL/NTSC mismatch, or something going on there.

Either:
(A) VCR heads damaged for that play mode
(B) The tapes are at fault, not the VCR. The JVC is just not "automagically" playing like the low-end decks. It may be doing conversion, a consumer feature not in prosumer decks.

[dpalomaki]

Could the playback speed issue be a control track issue reading? Perhaps the camcorder tapes are at one extreme of alignment and the S-VHS VCR at the other making it unable to reliably track the camcorder tape, while the other VCR's can track them.

[timtape]

The most common scenario where this happens is playing LP (half speed) recordings on a deck which can only play normal speed recordings. Are you sure your 7955 is designed to play back LP recordings?

[dpalomaki]

The 7955 user guide seems to indicate that the machine can record and play SP, LP, and EP recordings.
It also warns that EP speed tapes recorded on a different machine may not play properly.

Are the problem tapes originals from a VHS camcorder, or are they copies?

Do you see a tape speed indication on the VCRs that do play the tapes normally?

Does the 7955 display a tape speed when you play the problem tape?

To help isolate the issue: If you have a blank or scratch tape and a source of analog video stream perhaps try:

- record some video on each machine at SP, LP, and EP speeds (if available) leaving gap between the recordings.
- try play the recordings on each machine and note the results
- List results in a table similar to this:

Tape recorder on VCR A
-play on VCR A
- SP OK
- LP OK
- EP OK

Tape recorder on VCR A
-play on VCR B
- SP OK
- LP bad
- EP OK

And so on

[hodgey]

Does the time code on the 7955 change when playing back the tapes that play at wrong speed? IMO it seems most likely it has trouble reading the control track so it's just running at some default speed which will be approximately SP speed (while the tape is clearly LP as shown on the other VCR.)

Quote:

Originally Posted by lordsmurf

You have two very separate issues here.
Blackmagic cards drop frames, even with TBCs in use.

It will balk at TBC(ish) devices, actual TBC required.

Do you have any examples of it dropping frames with a TBC in use? And balking at TBC(ish) devices ? (assume you mean panasonic dvd-recorders here)

I've used a BM intensity a fair bit to capture vhs output passed via either a Sony RDR-HX750 and a Panasonic DMR-EH57, both with HDMI and component outputs and never experienced any frame drops on the capture side with either of those. (direct from vcr it black frames like crazy ofc). The S-Video input had some interference on it so never tried it much with my Datavideo TBC unit.

[lordsmurf]

Quote:

Originally Posted by hodgey

Do you have any examples of it dropping frames with a TBC in use? And balking at TBC(ish) devices ? (assume you mean panasonic dvd-recorders here)

I do somewhere. Black frames and audio desync still happened, and ever frame sticking at times.

During the pandemic, my research got disorganized. I have folders across multiple drives, and lack time to sort, low priority. However, I was mostly recreating issues that I've seen or read from others. In this forum, there are samples. Same for others, even the BM forum. I was loaned a BM card that I had to return..

Quote:

Sony RDR-HX750 and a Panasonic DMR-EH57, both with HDMI and component outputs and never experienced any frame drops on the capture side with either of those.

The issue with a TBC(ish) is exactly this:

Proper time base correction needs to have on both axis (axes). Not X and Y, but intra and inter, aka static and temporal, aka in-frame and frame-to-frame.

When you process with line TBC, you're only processing the intra, not the inter.

Genlock syncs two sources, and it was never really intended for videotape (ie, live camera editing, or linear editing).

Non-TBC frame sync just syncs itself against itself. It doesn't correct/realign anything, but rather locks the output to a simple clock. Simple clock. Simple. It can be easily overrun, and abnormal data is output.

The output of non-TBC frame sync will merely bake in any issues not corrected by the line TBC on the TBC(ish), including jitter, blended frames, etc. Simple frame sync generally do not delay.

TBCs rebuild/realign in buffer, then releases. The buffer can be as small or as large as desired, same for the allowed delay.

Line/field TBC generally have longer delay, for the strong the processing. And that's not a problem, because it's almost always inside VCRs, or SDI ingest.

But frame TBC really cannot delay much, do to processing only video (audio routed around), but also don't really need more than 1-2 frames (actually 1-3 fields). Remember, source frames are both too fast, and too slow, not precise. The frame TBC is not primarily worried about a clock, but rather proper output alignment.

Everything can be overrun, including both line and frame TBC. But TBCs often have generous buffers, whereas simple clocked frame sync really does not.

If your sources is "good", then it may be fine with just the single axis TBC, with the simple clock frame sync. But the problem here is that "good" is not visual. And most people have the wrong opinion on the condition of their videotapes, due to mere visual inspection.

Remember, you can't really see oxygen, but you require it. This is true of non-visual corrections that allow digital ingest. Having a mere line TBC, with non-TBC frame sync, is like breathing farts, ie a higher methane % compared to good air. It won't kill you (or the ingest), but it doesn't smell (or look) all that great.

When you further process to component or HDMI, you've already digitized the signal, and are simply feeding it to another. If you re-capture that via analog means, it's really no different from capturing a DVD player. The analog is gone, for better or worse, usually worse. (This is where PAL and NTSC take a heavy divergence, where PAL can have some limited success via HDMI output, and NTSC is egregiously harmful to the signal in almost all instances.)

Also noting most "HDMI output" is internally processed over composite, on consumer DVD recorder combo units.

[hodgey]

Quote:

Originally Posted by lordsmurf

When you further process to component or HDMI, you've already digitized the signal, and are simply feeding it to another. If you re-capture that via analog means, it's really no different from capturing a DVD player. The analog is gone, for better or worse, usually worse.

That's the case on S-Video and composite out too (and same on the Datavideo and AVT TBCs for that matter).

[lordsmurf]

Quote:

Originally Posted by hodgey

That's the case on S-Video and composite out too (and same on the Datavideo and AVT TBCs for that matter).

Sort of, but not in the same way.

It's the difference between output intended for a viewing device, and output intended for ingest/edit/distrib. Not the same. The goal of the TBC is (or should be) transparency. The goal of the HDMI and/or upscale is to force it into a new signal type, transparency doesn't matter (and in fact filtering is almost always part of it).

It's only "the same" in the broadest of senses, such as suggesting a human is "the same" as an ape, or cat, or gerbil, etc.