MTC Output
MTC (MIDI Timecode) carries SMPTE timecode over a MIDI connection. LTCast sends it continuously during playback so any MIDI-capable device β a DAW, lighting console, or media server β can lock to the current position and follow every seek or speed change.
Setting up a MIDI output port
Configure the MTC output port in Settings β Devices β MTC Output. The selector lists all available MIDI output ports on the system.
If you are routing MTC to software on the same machine, create a virtual MIDI port first:
- Windows β install loopMIDI (free, Tobias Erichsen). Create a port in loopMIDI, then select it in LTCast. Open the same port as MIDI input in your DAW or lighting software.
- macOS β open Audio MIDI Setup β Window β Show MIDI Studio β double-click IAC Driver β check Device is online β add a port. Select the IAC bus in LTCast.
For physical MIDI hardware, connect a USB-MIDI interface and select its output port in LTCast.
Quarter-frame mode
Quarter-frame is the standard MTC mode for continuous sync. LTCast sends 8 quarter-frame messages per SMPTE frame β at 25 fps that is 200 messages per second. The receiving device reads these messages sequentially to reconstruct the exact timecode position and locks its transport to follow. Quarter-frame mode provides smooth, continuous sync and is the correct choice for all normal operation.
Full-frame mode
Full-frame sends a single SysEx message each time the playhead position changes (on play, seek, or jump). The message contains the complete timecode value, making it easier for older devices that cannot parse quarter-frame streams. Full-frame is not suitable for continuous sync β it only reports position changes, not the continuous advance of the timecode. Use it only for devices that explicitly require it and cannot lock to quarter-frame MTC.
The MTC frame rate follows the detected or forced frame rate of the loaded audio file. Make sure the receiving device is configured to the same frame rate. A mismatch causes the receiving device to run at the wrong speed or refuse to lock.
MTC and MIDI Clock on the same port
The same MIDI port carries both MTC quarter-frame messages and MIDI Clock pulses. You do not need to configure two separate ports. Most MIDI-capable software correctly handles both message types on the same port and assigns each to its appropriate engine (timecode vs. tempo sync).