Proc Amp use case guide?

[will74]

Thanks again in advance for the incredible information and help you've given me with this forum. After much time of acquiring equipment and putting this off for various reasons, I have recently received my JVC HR S7900 from lordsmurf to complete my setup of JVC HR-S7900 VCR>AVT-8710>(sometimes) SignVideo PA-100 >ATI AIW 9200 to Huffyuv AVI in Virtualdub.

I've started to capture some tapes and things have gone well so far. I have done most of the tapes without the proc amp, but on a few, i've connected it up and played around with the black and gain settings to make a few adjustments.

That said, I'm trying to figure out how and when to use the proc amp.

I looked around this site (and the internet in general) to try and find a guide beyond the manual that comes with it, but couldn't find anything.

Here's what I've been able to figure out:

-I know that the hue and saturation adjustments are in almost all situations (outside of a color cast over the whole video) better done in post.

-I know that for this type of work, a really good, calibrated display is important. I have a decent IPS screen that has been calibrated with an X-rite calibrator, so it's pretty much the best i'm going to get.

-I also know that the IRE meter on the PA-100 can be very useful for keeping things within the viewable/legal limits.

I have read that you're trying to keep the histogram value in Virtualdub between 16-235 (inside the red areas on the side). Is that correct?

I know that it can be difficult to adjust these levels during capture since scene to scene the lighting can be drastically different and the histogram doesn't show up during capture. I think that this is where the IRE meter comes in. I can use it to adjust the luminance levels to avoid signal clipping in real-time while capturing. I also think that I read somewhere that you want to keep things in the IRE meter between 7.5-100, because there's a point below 7.5 where the capture doesn't really get anything from a 5 IRE and below. Is that correct?

Overall, when using the Proc Amp, are you trying to keep the levels between the low IRE (7.5 or whatever is the answer to my question above) through 100 without clipping?

Is another goal to try and fill the meter in the PA-100 for every scene from the low IRE through 100 without clipping?

Additionally, I know from doing some other video work, that for a video that you want to use to color grade/make adjustments in post, people often recommend capturing it in a "flat" profile on the digital camera, to give the most latitude for the edits later. When making any adjustments with the proc amp, should a "flat" output be the goal?

And finally, related to the above, as far as I can tell, when I've been able to capture successfully, I've used the "Overlay" option in Virtualdub, because I've had problems with CPU use (I think, although maybe I should try this again) causing audio sync issues when using the "Preview" option. How do you view the capture as it's happening? Is there a way to break out the signal to a separate monitor (without harming the signal going to the capture card) Or is there another method to view the video live while capturing? Or is the only option to do it the way I have been doing it, by using Preview to get to my starting point, then switching to Overlay right before I start capturing, and trying to use the sound from the video that's playing to tell when I need to stop capturing.

[trenog]

Hi everyone.

I basically have the same questions as @will74 posted above.

I've been buying up a vhs capture workflow with the following:
VHS Player: JVC SR-VS10U
TBC-like Passthough: Sony RDR-HXD870
Simple Frame TBC: DataVideo DVK-200
Proc Amp: Elite Video BVP-4+
Video Capture Card: ATI AIW PCIe (WIP)
Audio Capture Card: Turtle Beach Santa Cruz

But knowing how I should be using the Proc Amp for the best quality video input into the Capture PC is something I don't know about/what the common knowledge is.

Thanks!

[dpalomaki]

A few thoughts.

IMO, a proc amp should be used with a light touch, especially the BVP4 series which can really mess-up video if not careful. It can be used to make corrections to analog video before digitization thus avoiding the truncation/quantizitation errors that can come with digital processing, especially with 8-bit video. (A 6 dB correction to an 8-bit image could turn it into an essentially 7-bit image.) While the Sign Video gives 4 controls and some basic metering, the BVP-4 offers more controls but no metering. And one might enable you to get some special effect you are trying to achieve.

A good monitor and a real time waveform display are valuable assets when using a proc amp. And as noted above, individual scenes may call for different levels of adjustment, or none at all. It is rarely a set and walk away during capture device.

Thinks to avoid:
- proc amps with a high noise floor.
- pushing the blacks below 7.5 IRE (for NTSC, 0 IRE for PAL and NTSC-J)
- pushing highlights above 100 IRE
- over-saturating colors
- over increasing brightness/contrast/saturation in what are intended to be dim/dark scenes
- AGC in the system downstream of the proc amp can undo much of the good you have attempted.

Only use one it when you feel it is necessary to get a capture result with which you are happy.

[trenog]

Thanks for this feedback! It's very useful to know for when I start. I had heard about the aggressiveness of the BVP-4+, so I'll keep a light touch on the SP/Early-Gen tapes, and a bit more touchup on anything that is clearly missing some color/black detail.

For monitors I have a Dell S2716DG, which is a 1440p TN display for HD review, and I have a pair of Sony PVM-1354q for SD review. Those should be okay, right?

Both need to be calibrated still, but I have a Calbrite iDisplay Pro for that job.

For real-time waveforms, is that something my future WinXP box will take care of in software during playback? Or are there better ways to take care of that aspect of calibration?

Thankfully the AGC in this workflow is in the Sony DVD recorder, so I can play with various picture aspects up and down the chain as needed.

I also got myself an Extron MMX 42 SVA RCA for s-video switching in case I wanted to do an A:B check on whether the analog manipulation I'm doing with one of the workflow parts makes sense compared to another.

[Crazyates]

I'm also looking for information about this. I have a DVK-200, and wondering if I should be using this to tweak the brightness/contrast of really bad videos, or should I do it in post?

I have some home VHS from '92 that are dark indoors, and washed out outdoors. I also have my uncle's wedding that is super washed out. I thought it might be a degraded tape, but I have 2 copies that are identical, so it might be a bad recording?

I use Davinci Resolve for editing, but I'm pretty new to color work, and esp new to VHS work.

Quote:

Originally Posted by trenog

For monitors I have a Dell S2716DG, which is a 1440p TN display for HD review, and I have a pair of Sony PVM-1354q for SD review. Those should be okay, right?

Both need to be calibrated still, but I have a Calbrite iDisplay Pro for that job.

I had the S2716DG for a few years. It's a great gaming monitor, but the color accuracy was pretty bad. You could calibrate it to make it a bit better, but I'm not sure how good it'll actually be. A good uncalibrated IPS might as good as the calibrated TN panel, but a calibrated IPS is your best bet.

[lordsmurf]

Quote:

Originally Posted by Crazyates

I'm also looking for information about this. I have a DVK-200, and wondering if I should be using this to tweak the brightness/contrast of really bad videos, or should I do it in post?

Only if your monitor is calibrated.
And only if the TBC is calibrated -- some drift, and unity is not 0!

Quote:

I have some home VHS from '92 that are dark indoors, and washed out outdoors. I also have my uncle's wedding that is super washed out. I thought it might be a degraded tape,

Proc amp can help with this, but you don't want to "correct" against bad preview. It'll actually get worse.

Quote:

but I have 2 copies that are identical, so it might be a bad recording?

Likely.

Quote:

I use Davinci Resolve for editing, but I'm pretty new to color work, and esp new to VHS work.

That software is overly praised, and doesn't deserve it. Poor codec support for starters. The color tools really are nothing special compared to other NLEs.

Quote:

but a calibrated IPS is your best bet.

Mostly look to LG, some Dell, maybe a few ViewSonic still.

[Hushpower]

Quote:

Originally Posted by Crazyates

I have a DVK-200, and wondering if I should be using this to tweak the brightness/contrast of really bad videos, or should I do it in post?

Quote:

Originally Posted by Lordsmurf

Only if your monitor is calibrated.
And only if the TBC is calibrated -- some drift, and unity is not 0!

Wouldn't you'd be adjusting the brightness and contrast using the VDub histogram prior to capture? The DVK-200 is great at doing that with that nice big physical knob to twist.

[Crazyates]

Quote:

Originally Posted by Hushpower

Wouldn't you'd be adjusting the brightness and contrast using the VDub histogram prior to capture? The DVK-200 is great at doing that with that nice big physical knob to twist.

I've been doing some testing (aka fiddling and playing with the DVK), and that's what I've been doing. Using the VirtualDub histogram, I've been upping the brightness so the low-end isn't being cut off, and then lowering the contrast so as to not clip the highs. It does slightly better out of the gate, and then I can color edit later in post (using a good monitor like LS said earlier).

[lordsmurf]

Quote:

Originally Posted by Hushpower

Wouldn't you'd be adjusting the brightness and contrast using the VDub histogram prior to capture?

Histograms lie. You're putting blind faith into software. Bad move. Tools are great, but verify with your own eyes.

Quote:

Originally Posted by Crazyates

I've been doing some testing (aka fiddling and playing with the DVK), and that's what I've been doing. Using the VirtualDub histogram, I've been upping the brightness so the low-end isn't being cut off, and then lowering the contrast so as to not clip the highs. It does slightly better out of the gate, and then I can color edit later in post (using a good monitor like LS said earlier).

This is the middle ground between blind faith and total confidence. Not bad, not good, very neutral.

I hope it works out for you.

[dpalomaki]

One factor to be aware of that speaks to using a proc amp is that some capture devices may clip whites above 100 IRE and blacks below 7.5 (or 0 IRE). On the other hand some consumer gear will record and/or play super whites (above 100 IRE) and super blacks (below 7.5 or 0 IRE). Judicious use of a proc amp early in the workflow can help eliminate the loss of bright highlights and shadow detail in the "super" areas.

[oreo137]

Quote:

Originally Posted by dpalomaki

Judicious use of a proc amp early in the workflow can help eliminate the loss of bright highlights and shadow detail in the "super" areas.

I'm just starting to read up on proc amps and I'm wondering if anyone can elaborate on their opinion about where to place one in a workflow. "Early" seems to indicate immediately after a VCR, yes? On the other hand, I noticed LordSmurf has recommended adding it later in a workflow:

Quote:

Originally Posted by lordsmurf

Adding proc amp is optional, though useful. Either add it after external TBC, or it's embedded with one.

I might compare once I have the opportunity, but curious if anyone has thoughts in the meantime.

[lordsmurf]

Proc amp must come after frame TBC.

VCR with line TBC
> frame TBC
> optional items (proc amp, detailer, audio mixer, etc)
> and finally, the capture card or recorder

The proc amp will "bake in" timing issues (and/or cause further drop/etc type issues), and subsequent path TBCs will be limited in effectiveness.