Where to fit a proc amp?

[kodec]

In the following workflow, where to fit it?

VCR -> DVD RECORDER PASS -> TBC -> PC

From what I gather, between the TBC and the PC I presume?

[lordsmurf]

After the TBC, always.

[kodec]

Thanks.

[JVRaines]

Unless it looks better putting it somewhere else.

For example, some tapes are too hot going into my DMR-ES15 and I get white clipping unless I put the proc amp in front of it. That's why my processing gear is connected to a 4×4 matrix switcher — I can move things around by turning a few knobs.

[Cornucopia]

If it's an analog ProcAmp, and if the TBC is digital and has bitdepth of 10bits or less, I could see needing to use the ProcAmp upstream of the TBC so that it is passing a signal that is within normal signal parameters (black level, brightness, hue, saturation). Otherwise, there could be banding that you can't fully get rid of. But that's a special case.
...JVRaines beat me to it!

Scott

[lordsmurf]

The proc amp may alter the signal too much that the TBC is ineffective.
That's why.

As always, some unusual/uncommon exceptions.

The ES10 is (at best) a line TBC, not a external framesync TBC. That it is even considered a TBC at all can be contested, because it has too many holes in the processing to appease Macrovision.

[kodec]

No visible audio control buttons on the proc amp, don't know if it's doing something inside with the audio, nothing mentioned in the manual. Any point then of plugging the audio RCAs in the proc amp's audio jacks? Or just bypass it altogether and plug the audio into the PC directly?

EDIT: since it features multiple inputs, it's probably to mix and switch audio signals from one source to another.

[Cornucopia]

A proc amp primarily works on video signals. The audio is just along for the ride. This sometimes helps in some other instances where there ends up being a delay due to processing, as a unit that has both signals going through it should have delay compensation.
But most proc amps are simple analog devices with no appreciable delay, so it isn't really helping here.
Best practices say to go as straight through as possible. So I'd bypass the box, unless you had need to mix.

Scott

[kodec]

Yep, direct to the capture card it is then. And while we're at it, should I bypass the second step in my workflow and NOT plug the audio in the DVD pass as well, rather send it directly from the VCR to the capture card? I think I've read somewhere a while before that plugging the audio as well with the video in the DVD pass is rather a positive thing, recommended? Or it just doesn't matter in the end.

[Cornucopia]

You want the best capture quality. And that usually means as straight-through and unadulterated as possible. But capping must also maintain AV sync. If going through DVD chain helps that, it maybe worth it.
You should know best with your equipment chain, but you should verify with some A/B tests.

Scott

[JVRaines]

I always run audio direct to the converter, then add the appropriate delay when I trim the capture in VirtualDub. For example, my DVD recorder delays the video by two frames, so I delay the audio 67 milliseconds in VirtualDub.

[kodec]

Ok, I'll try running the audio to the capture card directly and see what's the difference between that and running it thru the DVD chain first together with the video, make the comparison of delays.

[jwillis84]

If your putting something to prevent false cp triggers, where would you put it in the chain?

I would guess "after" the tbc, before the recorder or capture card.. but I'm not sure.

[Cornucopia]

Since the purpose of a proc amp is to restore a video signal to to proper/legit/legal video levels, its features may be altered (or even defeated) if it is anywhere except immediately upstream of the capture card.

What you are wanting to do is get an OPTIMAL capture. Assuming the capture card/device is operating as intended and there isn't some confounding settings imposed on the capture, if the analog signal going into the capture is proper, the digital signal on output (not counting compression, subsampling) will be optimally transferred WRT signal-to-noise. IOW, each digital bit is as closely and fully representing the spectrum & dynamic range of the source as it can, with highest efficiency / least waste.

A similar or analogous process, methodology & intention occurs in sampling audio.
One doesn't do A->D at low (or too high) levels and normalize, because then the bits aren't storing the full capability of the signal, but instead are also storing some added noise or distortion.

Scott