Timecode, LTC and MTC
Frame addresses align music to picture, with LTC travelling as audio and MTC as MIDI.
Related
Timecode gives every moment a frame address, so music, picture and several machines can point at the same place.
The problem
A score must follow picture, a commercial must follow shots, and a live show must follow video playback. Counting bars does not match an editing application, so a shared ruler is needed.
How it works
Timecode reads hours, minutes, seconds and frames, with rates of twenty-four, twenty-five, thirty and twenty-nine point nine seven. LTC modulates the address into audio and records it on a track; MTC splits it into MIDI quarter-frame messages, four per frame. Both resolve only to a frame.
Settings and practice
Match the frame rate exactly, and confirm whether twenty-nine point nine seven uses drop frame. Set a common start offset; chase mode follows the master continuously, while trigger mode aligns only on large jumps. Record LTC on its own track and keep it away from stretching or pitch processing.
What to listen for
Check whether sync points still agree after ten minutes. Aligned at the start and drifting at the end means the frame rate or drop-frame setting is wrong.
Common misunderstandings
Timecode is not a tempo clock and does not set beats per minute. MTC carries position, not audio.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Sources
- LTC 与 MTC 的帧格式和帧率定义，依时间码与 MIDI 规范核查，未抄文本
- 影视配乐的追逐与触发同步方式，依后期制作通识核查，未抄文本
Used for fact-checking only; all prose is original.