Genlock / Black Burst

showstack / protocols / genlock

Genlock / Black Burst

Also called Black Burst, BB, House Sync, Bi-level Sync.

An analog composite video reference signal (a 'black' picture with color burst) distributed over coax to lock cameras, switchers, and video servers to a common timing reference; the SD-era precursor to tri-level sync for HD video systems.

Timecode and syncPaid specReportedHistorical

Clock and sync Tiny, ruthlessly regular

Almost no bandwidth. Carries no content at all, only agreement about when. Its value is entirely in its regularity.

What kills it. Jitter, an unaware switch delaying the timestamps it was meant to correct, and two devices both convinced they are the master.

The four flows, and why the model is worth having →

What goes wrong

Black burst is an SD-format reference; HD/UHD systems generally use tri-level sync instead, which has different pulse levels and isn't interchangeable on the same distribution amp.

Purely a timing reference with no metadata - it must be paired with LTC/VITC timecode if frame-accurate identity information is also needed.

What speaks Genlock / Black Burst (14)

14 products — 14 hardwareshow all

Product	Direction	Notes
Alcorn McBride A/V Binloop HD Alcorn McBride	in	Frame reference.
Analog Way Alta 4K Analog Way	in	Reference input.
Analog Way Aquilon RS4 Analog Way	in	Reference input.
Barco Event Master E2 Barco	in	Genlock reference input.
Blackmagic ATEM 4 M/E Constellation HD Blackmagic Design	in	Blackburst / tri-level reference input.
Brompton Tessera S8 Brompton Technology	in	Frame reference.
Brompton Tessera SX40 Brompton Technology	in	Genlock reference input for camera-synchronous operation.
disguise vx 4 disguise	in	Reference input for output phase lock.
Evertz 5601MSC Master Sync and Clock Evertz	out	Blackburst and tri-level reference.
Megapixel HELIOS LED Processing Platform Megapixel VR	in	Frame reference — the whole point on a camera stage.
Mo-Sys StarTracker Mo-Sys Engineering	in	Frame reference so tracking data lines up with the picture.
NovaStar MX40 Pro NovaStar	in	Genlock reference for camera work.
Rosendahl nanosyncs HD Rosendahl Studiotechnik	out	Blackburst and tri-level video reference.
stYpe RedSpy stYpe	in	Frame reference.

The words for it

Glossary entries that name Genlock / Black Burst, with the false friends that catch people out.

Frame rate影格率How many complete images a video signal carries per second. On a show it is a system-wide decision, not a per…

Sources

Understand the mechanism

Show networks How it all runs together Node graphs and game engines Why the picture is black

Something wrong, or missing?

Known gaps on this entry: default_ports, first_published, implementations, spec_url. If you can source one of them, that is a ten minute pull request.

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