showstack / protocols / ltc
LTC
Also called Linear Timecode, Longitudinal Timecode, SMPTE timecode, SMPTE.
SMPTE time and control code encoded as a biphase-mark audio signal, 80 bits per frame, so it runs down any audio path in the building. It is still the least fragile way to hand one clock to lighting, sound, video and automation at the same time.
Stewarded by SMPTE (Society of Motion Picture and Television Engineers).
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.
What goes wrong
The 80-bit word carries no frame-rate field. The reader infers the rate from the incoming bit rate, so a 25 fps generator into a 30 fps reader produces numbers that look plausible and quietly drift.
Drop-frame at 29.97 skips frame numbers, not time. Cue sheets written non-drop against a drop-frame master run out by roughly 3.6 seconds an hour, and the error is invisible in the first five minutes of a tech.
ST 12-1 asks for 1 to 2 V peak-to-peak with 40 microsecond rise and fall times. Route LTC through a compressor, a de-esser, a lossy codec or a consumer wireless link and the edges round off until the reader loses lock.
LTC is unreadable at very low transport speeds because there are no transitions to clock from. A paused master stops sending position entirely, so downstream devices either freewheel or drop out.
It is an audio signal, so it bleeds. Keep it off adjacent channels, out of foldback and out of anything that goes to a speaker; a burst of LTC in the PA during a quiet scene is a career moment.
The eight four-bit user groups are free-form and every manufacturer fills them differently. Do not assume date or reel data survives a round trip through a converter or a distribution amp.
What speaks LTC (60)
60 products — 35 hardware, 25 softwareshow all
| Product | Direction | Notes |
|---|---|---|
| Ardour Ardour Community |
bidirectional | LTC generate and chase, built in. |
| ArKaos MediaMaster ArKaos |
in | LTC sync. |
| Avolites Titan Avolites |
in | SMPTE/LTC listed on T2, T3, D3, D3 Core, D7, D9, Arena, Tiger Touch 2 and Sapphire. A T2 plugged into another console adds an audio/LTC input. |
| ChamSys MagicQ ChamSys |
in needs licence |
Timecode receive (Art-Net, MIDI, LTC) is an Unlocked-mode feature; demo and Core mode will not chase timecode. |
| Depence Syncronorm GmbH |
in | Listed as "SMPTE" among Depence's supported protocols; matched here to SMPTE/LTC timecode by name. |
| disguise Designer disguise |
in | One of the documented timecode sources alongside MTC, MIDI beat clock and system time. |
| Eos Electronic Theatre Controls (ETC) |
in | SMPTE/LTC timecode is receive only and arrives via a Net3 Show Control Gateway. |
| Finale 3D Finale 3D |
out | Scripts are executed against timecode by the firing system. |
| HeavyM HeavyM |
in | Timecode-driven playback, depending on version. |
| Hippotizer Green Hippo (an ACT Entertainment brand) |
in | Sync Manager receives LTC from an audio input (left channel), a factory-fitted Alpermann+Velte card, or USB interfaces (Rosendahl Mif4, CB Electronics TC-5, Adrienne Electronics USB-LTC). |
| Medialon Control System Medialon (Barco) |
bidirectional | LTC generation and chase. |
| Millumin Anomes (Philippe Chaurand) |
in | LTC over an audio input; supported framerates are 24, 25, 29.97 DF and 30. Millumin also ships a free TimecodeClock app that generates LTC, MTC or its own network timecode. |
| Mitti Imimot |
in | Timecode sync on supported versions. |
| Modul8 GarageCUBE |
in | Timecode sync via third-party bridges. |
| ONYX Obsidian Control Systems |
in needs licence |
LTC via the SMPTE IN 3-pin connector on M6+ consoles, or audio LTC via an audio interface. Timecode is only fully enabled from the NOVA+ tier. |
| PIXERA AV Stumpfl |
in | Timecode. |
| Pro Tools Avid |
in | Chases LTC via a synchroniser or interface. |
| ProPresenter Renewed Vision |
in | Timecode sync on supported versions. |
| Q-SYS Designer QSC, LLC |
bidirectional | Stock schematic components: the SMPTE LTC Reader decodes LTC from an audio input per SMPTE 12M and exposes timecode fields as control pins for Lua; the SMPTE LTC Generator is the encoder counterpart. |
| REAPER Cockos Incorporated |
out | The stock SMPTE LTC/MTC Timecode Generator produces an LTC audio signal at a chosen frame rate and start time. Real-time LTC chase is not part of it. |
| Show Cue System (SCS) Show Cue Systems |
in | Timecode chase. |
| Smode Smode Tech |
in | LTC for timeline sync. |
| Stage Precision Stage Precision |
in | Timecode input. |
| Unreal Engine Epic Games |
in | Timecode via plugin and hardware. |
| WATCHOUT Dataton |
in | Handled by the LTC Bridge component. |
| 7thSense Delta Media Server 7thSense |
in | LTC for show sync. |
| Alcorn McBride A/V Binloop HD Alcorn McBride |
bidirectional | Timecode master or slave. |
| Alcorn McBride V16Pro Alcorn McBride |
bidirectional | SMPTE LTC in and out on XLR, 600 ohm balanced, 1-4 V peak to peak. The V16Pro reads and generates; the V4Pro does not. |
| Allen & Heath dLive S7000 Allen & Heath |
in | LTC input for scene firing. |
| Analog Way Picturall Mark II Analog Way |
in | LTC sync. |
| Avid VENUE S6L-32D Avid |
in | LTC for snapshot automation. |
| Avolites Ai Q3 Avolites |
in | Timecode. |
| Avolites Arena Avolites |
in | Timecode. |
| Avolites Diamond 9 Avolites |
in | LTC input for timecoded cue lists. |
| Avolites Tiger Touch III Avolites |
in | LTC timecode input. |
| Brainstorm DXD-8 Distripalyzer Brainstorm Electronics |
bidirectional | Reads, analyses, regenerates and distributes LTC. |
| ChamSys MagicQ MQ80 ChamSys |
in | Timecode for playback. |
| ChamSys MagicQ MQ500M Stadium ChamSys |
in | Linear timecode input for timecoded playbacks. |
| Christie Pandoras Box Christie |
in | LTC timeline sync. |
| Dataton WATCHPAX 60 Dataton |
in | Timecode for synchronised playback. |
| DiGiCo Quantum 338 DiGiCo |
in | LTC for snapshot firing against timecode. |
| disguise gx 3 disguise |
in | Via Designer's timecode sources. |
| disguise vx 4 disguise |
in | LTC timecode input for show sync. |
| Eos Apex 5 ETC |
in | SMPTE timecode is receive only and needs a Response show control gateway. |
| ETC Eos Apex 10 ETC |
in | Timecode. |
| ETC Ion Xe 20 ETC |
in | LTC timecode in. |
| Evertz 5601MSC Master Sync and Clock Evertz |
bidirectional | Timecode. |
| grandMA2 full-size MA Lighting |
in | LTC input for timecode-driven sequences. |
| MA Lighting grandMA3 light MA Lighting |
in | Timecode. |
| Green Hippo Hippotizer Karst+ MK2 Green Hippo |
in | Timecode. |
| Hog 4 High End Systems |
in | Linear timecode input on 3-pin XLR. |
| Medialon Showmaster Pro Medialon (Barco) |
bidirectional | Timecode. |
| Midas HD96-24 Midas |
in | LTC input. |
| Modulo Kinetic Modulo Pi |
in | LTC for timeline sync. |
| Obsidian Control Systems NX4 Obsidian Control Systems |
in | LTC timecode in. |
| AV Stumpfl PIXERA one AV Stumpfl |
in | LTC timeline sync. |
| Rosendahl nanosyncs HD Rosendahl Studiotechnik |
bidirectional | LTC generate and read. |
| TAIT Navigator TAIT |
in | Timecode-driven automation sequences. |
| Yamaha RIVAGE PM7 Yamaha |
in | LTC input for scene automation. |
| Zero 88 FLX S48 Zero 88 |
in | LTC input for timecode playback. |
Open source implementations
- libltc — C, LGPL-3.0
Typical use
- Master clock from a timecode generator to lighting, sound and video
- Locking playback, automation and pyro to a backing track
- Striping a reference clock onto a spare track of a multitrack
- Feeding a console's timecode-triggered cue list from front of house
The words for it
Glossary entries that name LTC, with the false friends that catch people out.
Biphase mark encoding雙相符號編碼The line code LTC uses. There is a transition at every bit boundary, and a one gets one extra transition in t…Drop frame丟幀時碼A timecode counting scheme that skips frame numbers 00 and 01 at the start of every minute except every tenth…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…Jam sync同步鎖定Matching a timecode generator to incoming code and then continuing to generate in step. Continuous jam keeps …
Sources
- SMPTE ST 12-1:2014 — Time and Control Code — SMPTE primary
- Setting the Standards Free — SMPTE opens its full standards library at no cost — SMPTE primary
- libltc — Linear/Longitudinal Time Code library — Robin Gareus
Understand the mechanism
Something wrong, or missing?
Known gaps on this entry: default_ports, first_published. If you can source one of them, that is a ten minute pull request.
Edit this entry on GitHub — one file, editable in your browser, and your handle goes on it permanently.
Work at SMPTE (Society of Motion Picture and Television Engineers)? Confirm or correct this entry — it is free, it stays free, and nothing about it is for sale.