SMPTE Timecode: The 80-Bit Audio Sync That Keeps Video and Music in Lockstep
Synchronisation and SMPTE timecode (time code)
Phil Rees, creator of the TS1 MIDI tape sync unit, demystifies SMPTE/EBU timecode—the standard that lets audio, video, and music gear play in perfect time. He explains the Bi-Phase Mark modulation that encodes time as audio frequencies, the 80-bit data frame with its BCD time address, user bits, and sync word, and the quirks of frame rates like 29.97 fps and drop-frame. A clear technical tour for anyone curious about how tape machines and sequencers chase each other.
This straightforward scheme of modulation is amazingly robust and compatible with a range of real world audio channels, including tape recorder tracks.
- linsomniac
I wish more cameras with GPSes supported SMTPE or something to mark the video with a time code. I get the sense that GPS time is accurate to within 1/30th of a second, if not way way more, but even if it just got me in the neighborhood so I could nudge it a frame or two one way or another.
I like recording things like my kids performances with a GoPro or two, and sometimes my wife or I get some shots on our phones. Multi-cam can be fantastic when you have people walking around in front of cameras, for example.
I used to have a majorly hard time syncing the multiple cameras shots, though the last time I did it (a couple months ago) I had much better luck with the "sync using audio" feature, in the past I've had problems. But why can't we have a timecode with the video stream, in the cases of GPS cameras (I think everyt camera I have now has a GPS)?
- monster_truck
A perfect resource, still as relevant as ever.
Genlock, Clock Gen and their friends are at the top of the "check all of the responsible hardware, the ports, and the cables" list when someone is having a flaky problem that doesn't make sense to anybody. Shortly followed by 44.1 vs 48khz and 59.94 vs 60fps being wrong somewhere
- windowliker
Phil Rees products were an absolute godsend in the 90s when most hobby and budget studios were still mainly all hardware being recorded to tape of some description. You would often find multiple little red and black boxes doing various conversion and routing jobs. And they all powered straight off the mains without a big heavy internal linear supply, or external wall wart, which was a great help during late nights where the right PSU may have gone walkies.