Frame Sync vs. TBC vs. GenLock

[Adam Attarian]

Hey There,

I’m very confused into what the above three pieces of equipment. I know what a FS does, but how does it differ from a TBC? Could some one please explain the differences between a Frame Sync and a TBC, where they would be used, etc?

Also, what is a genlock, what is it used for, where is it used, etc? I know it splits and blocks one of two sources of video, but I don’t know why.

Thanks a lot!

Adam Attarian
Intern at WRAL-DT

[Nathan Duffy]

Frame Sync vs. TBC vs. GenLockA Time Base Corrector and a Frame Synchronizer
do essentially the same thing, they match a video source timing to a
reference source. Often the two names are used interchangeably, but my
understanding is that a true TBC corrects timing by sending a timing signal
back to the source called advanced sync, where a frame sync has a video
frame buffer that stores the video and starts the new frame at the same time
as the reference video.

Because a TBC sends an advanced sync signal to correct timing, it can only
be used on sources that have an external sync input, mast commonly a tape
deck.

I'm not sure I fully understand your question about what a genlock is. A
genlock input on a device such as a camera is a reference sync input,
usually black burst but most any video from the system your syncing up to
will usually work. It allows the device that is genlocked to time itself to
the system sync. I have found that "reference loop", "genlock loop", and
"sync loop" are used interchangeably in labeling on equipment connectors.

hope this helps!

"Adam Attarian" <ad...@adama.am> wrote in message
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[David Winter]

Maybe the difference between a device which rebuilds a frame's synch pulses
by digitising and storing the frame until all the data is in, recreating all
frame and field synch pulses, scanline synchs and then outputs (broadly a
TBC, irrespective of external synch or internal only) COMPARED to a device
which recognises the synch pulse and regenerates it (and the colour burst)
in real time, which means there is a few microseconds lag. The latter works
best with fairly good video, reducing the effect of generation loss. These
do little for and could actually make worse a severely degraded picture. I
have one.

A full TBC can improve a poor picture's synch, and hence verticals, and
hence crispness.

Many camcorders have internal TBC (notably Sony Hi8), but my guess is that
they're limited.

I also have suspicions about the voltage of the synch pulses from small
camcorders (even with TBC) vs a full mains powered TBC or industrial VCR.

DW

"Nathan Duffy" <na...@bectv.org> wrote in message
news:mxmX5.3194$Ep3.5...@news.uswest.net...
: Frame Sync vs. TBC vs. GenLockA Time Base Corrector and a Frame

:
:

[mediamaniac]

hi adrian
a time base corrector can sync one video signal to another, but can do
more: it can do some corrections on the incoming video signal, can look
for dropouts on analogue video tape, and working as a framstore it may
even sync video sources which have no external sync input. genlocking
means that one video unit is synced to another, but normally its not a
complete synchronisation as you`d get via tbc as genlocking is done via
composite video or a blackburst signal. this is without problem in
syncing video cameras, but you`ll see the difference between sinple
genlocking or complete external synchronisation/tbc, which is more
stable and gives less problems with colors etc.
kai

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