Dropped frames - What difference does frame synchronizer/TBC make?

[premiumcapture]

All other things being equal, having all the right equipment to capture without dropped and inserted frames for clean tape, what difference does a frame synchronizer/TBC make to a capture? Does it 'invent' new frames or will it drop them too?

[dpalomaki]

Dropped frame as in digital capture hic-ups, bad drop outs on analog tape, or timecode?

[premiumcapture]

If a tape is damaged and can't be read properly by the VCR, and the VCR is hooked up to a TBC, what is actually sent by the TBC?

[dpalomaki]

Probably depends on what the TBC was designed/configured to do.

Could be a repeat of the good last frame, could be a rock solid frame of video noise with excellent sync and burst, or maybe a blue (or some other color) screen.

[lordsmurf]

A "frame sync TBC" duplicates -- it repeat the last good frame. Lots of video hardware newbies, who also love to analyze everything frame by frame, often mistake the "duplication" as bad. It's not. The original frame was "un-digitizable" because it was junk.

VirtualDub only reports what happens on the software side -- not the hardware before it.

This assumes the frame sync is working properly.

Or that it's a "TBC frame sync", not just a "frame sync". I've never found a good way to explain this. It's why DVD recorders and other devices with "frame sync" can drop frames, insert garbage, and have various errors. While "TBCs" (that are really "TBC frame syncs", like the TBC-100, etc) buffer it like a TBC. Here, I think the buffer is the key, but don't quote me on it.

Part of the issue is understanding what "timing" is. It's not 1D or 2D, as most think, but 3D (width, length, time). It's also both visual and signal based.

The Panasonic DMR-ES10 is an example of a DVD recorder that can fix some line issues, but still is not a true TBC. It's also not a frame sync, because of Macrovision enforcement.

One extra effect of the external TBC is vertical "jitter" (non-techical jitter, or vertical "bouncing"). The TBC-1000 corrects beyond mere frame syncing. That's on reason why it's a TBC. It's not line corrections, but more than simple frame sync. Note that this is not vsync, either -- not that "vertical".

Frame syncs work on the time axis.
Line TBCs mostly work on the image axis.
External TBC frame syncs mostly do the first, and some of the latter.

You also have genlocks, which happen after frame syncs, and are not necessarily TBCs.

I want to look over some notes first, then get back to you. Some of this overlaps with the myth forum question.

I've never felt entirely comfortable with answers on "What is a TBC?" because so many devices blend functions (line TBC, field TBC, frame sync, gen lock, proc amp, etc). And then because of this looseness in definition, companies have gone one further and expanded the definition of "TBC" to include not-really-TBC device features. It's become somewhat of a marketing term, and was distorted.

Yes, that means that the TBC-1000, AVT-8710, etc, is one of these frankenstein devices!

Not an easy topic.

[premiumcapture]

Quote:

Originally Posted by lordsmurf

I've never felt entirely comfortable with answers on "What is a TBC?" because so many devices blend functions (line TBC, field TBC, frame sync, gen lock, proc amp, etc). And then because of this looseness in definition, companies have gone one further and expanded the definition of "TBC" to include not-really-TBC device features. It's become somewhat of a marketing term, and was distorted.

There's a lot of info on that post that is definitely great for getting a first-timer's feet wet, but lately I have been looking at modern, newer alternatives, such as the newer Kramer unit and the BrightEye, and have wondered how much of a difference these units really make.

I recently captured some tapes without anything in between and did not drop/insert frames at all. I have a faster system than most capture setups (Core i5, 8GB RAM) with an external USB 3.0 drive and wondered if it was just blind luck or my system was fast enough to keep up with the choppy framerate of the VCR.

I went looking for technical information and came back with conflicting information and conflicting marketing. I think its pretty important to know how each type of unit works, the difference it makes, and current availability to help someone who is new to this make an equipment decision.

I have been at this seriously since December, and have yet to come to a decision, but I am getting closer.

[lordsmurf]

CPU speed has nothing to do with it -- in terms of replacing a TBC, and in terms of simply not being fast enough to process/save the incoming video stream. I bet you'd have more issues if you tried uncompressed YUY2.

Yes, luck. It happens, sometimes for several tapes in a row. I've done it, too!

I've been at it for years, and never crafted (or found) a 100% satisfactory definition. So good luck.

EDIT: You should read this 2010 VH conversation that I was part of: http://forum.videohelp.com/threads/3...-you-use/page3
And you'll see a wide array of yes/no issues, and from experienced users.