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Originally Posted by Gary34
TBCs don’t insert frames.
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Correct.
What a frame TBC does is right there in the name: timing correction. The video is input, and RAM buffers release temporally timed to perfection. Only when a signal is awful does a TBC fail to properly time to 29.97 or 25. Even "weak (frame) TBCs" tend to properly released at the proper internal, and the "weak" part manifests as visual distortions.
Non-TBC frame syncs attempt to time based on a rudimentary clock, with low/no buffer. Those are what tend to give up with milliseconds (ms) and insert/dupe. Sometimes drop, if the insert/dupe range has to expand too far.
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Originally Posted by aramkolt
It has never been completely clear to me, but if when using virtualdub you aren't seeing any dropped frames or vertical jitter, |
But is it setup correctly? Lots of people follow terrible guides that wrong instruct them to turn off (uncheck boxes) that essentially disables drop/insert frame reporting.
If I close my eyes, you can't see me?
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If there are periods of time where it takes too long for the next frame to arrive, virtualdub will just "insert" a null frame which just says to keep displaying the last good frame.
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No, not necessarily. More often, it just drops. Capture software sort of acts like a weak/pathetic non-TBC frame sync. If frame syncs and TBCs were Punch-Out characters, software (VirtualDub, OBS, AmarecTV, whatever) is Glass Joe. The saddest most pathetic character in the game, one punch can be TKO.
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This is basically what a frame TBC also does,
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No.
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you just don't know that it happened because the TBC doesn't tell you statistics.
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Not accurate. Some actually do report. Just not the units we need for consumer SD analog videotapes. But the main difference is again how the signal interacts, artifacts manifest, timing tends to be fine even when images are butchered. The wrong TBC will just burn-in problems. You can test this with a "pizza box" broadcast rackmount TBC, where output timing is fine, but image has massive issues.
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Logically, adding a full frame TBC would actually be HARMFUL in the above situation as they do impart conversion losses as they go from analog to digital then from digital back to analog.
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No.
As I stated elsewhere, too much is made of A>D>A, mostly by people that have limited TBC knowledge, or have experienced bad hardware. A key tenet of a quality TBC is transparency, meaning it functions without you seeing any ill effects. Some have it, many do not. When you dumpster dive TBCs, and start to dive into TBC(ish) items, transparency falls off a cliff.
All TBCs add some % of processing noise (in test patterns), but quality TBCs tends to be drowned out by the tape noise, or the VCR noise, or capture card noise. And "noise" here refers to everything from geometry to color accuracy, not a narrow definition of "noise" (so not grain, or electrical, or whatever).
To borrow from my favorite crass TBC analogy, the frame TBC is like a condum/rubber, the line TBC is like the pill/IUD. To be protected (from bad captures), you need both. Without any protection, you get STDs and unexpected crotch goblins (aka dropped frames, audio sync issues, etc ~ bad captures). Lots of people tempt fate here, and many (most?) lose that game of Russian roulette.
The comparisons are pretty funny on this thread.
