Proc Amp...When to Use?

[jberry]

Jsut a quick question...when is a proc amp really necessary? Is it for only really old footage? Can you get away with just an enhancer if your footage is pretty good?

thanks

[gshelley61]

Proc amps are used for correcting black level (brightness), luma (contrast), color and hue (tint, white balance). Nearly every analog video source can use a little correction due to differences in playback gear, mastering and duplication variables, etc. Some sources need more correction than others, of course.

I can't imagine doing any restoration or conversion work without the aid of a good proc amp.

[jberry]

thanks!!! So what is the difference between a proc amp and a video enchancer...and when do you use each one?

for example:

proc amp at signvideo:

http://www.signvideo.com/single_dual_proc-amp_video-processor.htm

video enchancer at signvideo:

http://www.signvideo.com/dr1000_image-enhancer_video-processor.htm


just trying to figure out what to buy!!!!

[edDV]

"Video enhancer" is usually VooDoo for the clueless. A true proc Amp gives you control of the variables that matter. Pro's seldom say "enhancer".

Black level (AKA brightness)
Video gain (AKA contrast)
Saturation = amount of color (too much is bad)
Hue (NTSC only) for adjusting green vs pink

After you get all that right (ideally using a waveform monitor), then other filters can be applied.

Sign Video's "enhancer" does some realtime filtering. I'd search for reviews as to effectiveness.

detail + sharpness - usually the same thing. These boost high frequencies which for VHS may only result in more noise and chroma buzz.

core plus black (under term noise reduction) - sounds to me like these controls just reverse detail and sharpness filters. Potions and curses.

[gshelley61]

Video image enhancers/detailers/sharpeners basically allow you to boost the high frequency end of video signal spectrum, which can result in greater perceived clarity and sharpness. Some units do this better than others... the SignVideo DR-1000 is excellent.

Less is more when applying sharpening to video. Mild enhancement can bring out some detail (depending on the source quality), but over-doing it will produce excessive grain and noise, edge ghosting, and an unnatural appearance.

[jberry]

so the proc amp really all that is needed then? just forget the enhancer?

[gshelley61]

so the proc amp really all that is needed then? just forget the enhancer?

It depends on who you ask... I use mine on virtually all of my analog video captures. It makes a noticeable difference, and I like a more detailed, sharper picture. Some people like a smoother, softer picture (and you get less encoding artifacts that way, too).

I do not use sharpening on digital video sources.

[jberry]

thanks for all your replys...what proc amp do you use then

[lordsmurf]

so the proc amp really all that is needed then? just forget the enhancer?

I tend to use it on anything that isn't perfect (or close enough). This tends to be most VHS tapes. Even commercial releases.

[Marvingj]

Proc amps & Video enhancers are used for restoration & tweeting. To me I would rather used stand alones than the computer generated stuff. I like the hands on approach. Just my 2 cents.

[edDV]

Proc Amps fix levels (and hue for NTSC). This is the first step and prepares the signal for optimal A/D conversion.

I'd argue that enhancement filters are better applied in the digital domain after the composite signal is decoded into YUV components.

[lordsmurf]

Once you go digital, about 75% of your options are lost. It digitizes the error into a new signal, and can no longer be corrected.

[edDV]

Once you go digital, about 75% of your options are lost. It digitizes the error into a new signal, and can no longer be corrected.

I agree for levels adjustment (Proc Amp) into a 8bit A/D but cheap analog "enhancement" hardware is likely to do more harm than good to the signal (Y/C separation is usually necessary).

[lordsmurf]

cheap analog "enhaancement" hardware is likely to do more harm than good

Yes. So true.

[jberry]

thanks again all....so I guess to summarize then I am better off buying the Signvideo proc amp I mentioned above as opposed to Signvideo's DR-1000 "enhancer" or Sima's SCC-2.

This correct. Thanks for all the good info!!!!

[Wile_E]

Do Proc Amps and "enhancers" work in the analog or Digital realm? Right now I have a JVC VCR and Canopus ADVC. The JVC TBC/DNR already digitizes everything before spitting it back out to analog for the Canopus. Then the Canopus has to digitize it again. I am curious how much of the original analog signal is thrown away from the repeated digital compression of each frame?

I assume these devices use some sort of compression(like JPEG) to digitize and store each frame in it's digital buffer. My VCR only has 4MB of frame buffer, so that can't hold too many frames. I seriously doubt they would use a RAW/TIFF/BMP format to digitize each frame. That would need a lot more memory than 4MB. For experiment, I created a 720x480 TIF image(uncompressed). It is about 980KB. 4MB would only leave room for four frames.

We all know that if you keep re-saving a JPG image, it will eventually degrade to a point that everything looks blocky or has a watercolor effect. Would someone please enlighten me on this subject?

[gshelley61]

The external proc amps and sharpeners (enhancers) that I am aware of are analog. TBC's are digital by nature. A four frame storage buffer on a TBC would be considered excellent. Not that long ago, even professional TBC's stored only a line or two, not a full frame. of course, newer units with frame synchronizers will buffer four or even eight frames.

[Dr_Layne]

Having used the DR-1000 myself, I can tell you this; you will find it's needed less often than you think. I've only used it on severely softened video. The results can be quite amazing with little artifacts. I'll try and post some screen caps of what I have done with it.

STeve

[Wile_E]

Dr_Layne, Yes can you please post some before/after shots? It would be nice to know what the results are like. I have several VHS tapes that are really soft. I tried using the sharpening filter built-in on my VCR, and on my Canopus ADVC-300, but they exaggerate the noise too much. Even a little bit of sharpening makes it look grainy. Hopefully a dedicated unit like DR-1000 would be better.

The TBC in the JVC VCR is line-based, not full frame. But for the digital filtering, I suppose they put the whole frame in, to digitize it. Now, what is the compression used and how many frames are stored in the 4MB? I would like to know.