LTC Audio Output

LTC (Linear Timecode) is SMPTE timecode encoded as an audio signal — it sounds like a distinctive digital chirp on an audio cable. LTCast generates this signal in real time and outputs it through an audio device. Any device that has an LTC input (lighting console, media server, audio recorder, or another instance of LTCast) can lock to it.

Recommended virtual audio setup

If you are routing LTC to software on the same computer rather than a physical cable, use a virtual audio device:

• Windows — install VB-CABLE (free, vb-audio.com). Select CABLE Input as the LTC output device in LTCast. Connect CABLE Output in the target application as its audio input.
• macOS — install BlackHole (free, ExistentialAudio GitHub). Select BlackHole as the LTC output device. Route BlackHole to your interface using Audio MIDI Setup → multi-output device if you also need to hear the music.

For physical cabling, select your audio interface output in the device selector and connect the interface's output channel to the LTC destination with a standard audio cable (balanced XLR or TRS recommended).

Configuring LTC output

Open Settings → Devices. The LTC Output selector shows all available audio output devices. Choose the device that will carry the LTC signal.

• LTC Level — output level in dBFS. The recommended range is −3 to 0 dBFS for Resolume Arena and most LTC readers. Devices with analog inputs may need a lower level to avoid clipping the input stage. Right-click the level slider to reset it to 0 dB.
• LTC Channel — for stereo output devices, LTCast puts LTC on one channel and silence on the other. Select Left or Right depending on which physical output your cable is connected to.

Mute and decode-only mode

Enable Mute (decode only) in Settings → Outputs to stop broadcasting LTC audio while still decoding any incoming LTC signal. This is useful when monitoring a show without broadcasting — for example, during a quiet rehearsal segment where you want to read the timecode without sending it downstream.

Verifying LTC output

After configuring the device and level, press Play on any song. The LTC signal indicator in the status bar should show TX (transmitting). On the receiving device, confirm it shows timecode locked. If the receiving device shows no signal, check: the correct output channel is selected, the virtual audio device (VB-CABLE or BlackHole) is running, and the level is not set to minus infinity.