Timecode Synchronizer

The Timecode Synchronizer, in Timing/Control, converts numeric timecode and speed inputs into a smoothed speed signal. Small position differences are corrected by changing speed; sufficiently large differences produce a timecode correction.

It does not decode an audio LTC signal or MIDI messages itself, and adding it does not automatically synchronize score’s transport. Connect a decoder or numeric source upstream, and route its outputs to the appropriate playback controls downstream.

Inputs and outputs

Port	Meaning
Input Timecode	External position, in the units selected by Input format.
Input Speed	Playback speed ratio: `1` is normal speed, `0` is stopped, negative values indicate reverse motion.
Input Validity	Whether the external timecode can be used. Its interaction with Speed depends on Sync Mode.
Output Speed	Smoothed, corrected playback speed.
Output Tempo	Output speed multiplied by 120; this is a fixed reference conversion, not a measurement of the source’s musical tempo.
Output Timecode	Position correction at initialization or when a position jump exceeds the threshold; not a continuous position readout.
Output Estimated Speed	Speed derived from timecode history in Timecode mode; do not treat it as a second corrected-speed output in every mode.

Input format and Output format independently select Seconds, Milliseconds, Microseconds, Nanoseconds or Flicks. One second is 705,600,000 flicks. The position error and Jump threshold are evaluated in seconds regardless of the chosen external units.

Choose a synchronization mode

Both follows Speed and corrects drift against valid Timecode. When Validity is false, a Speed strictly between -10 and 10 is still accepted; loss of valid timecode alone therefore does not necessarily trigger If no sync.
Speed follows Speed while Validity is true, without position correction.
Timecode estimates speed from changes in Timecode while Validity is true. Speed estimation window sets the history duration in seconds; Speed filter strength smooths that estimate.

Correction controls

Control	Effect
Jump threshold	A position error larger than this value causes a position correction instead of only a speed adjustment.
Max speed correction	Limits correction relative to the magnitude of the base speed. At zero base speed this proportional correction limit is also zero.
Correction time constant	Divides the position error when computing the desired speed adjustment; larger values make correction gentler.
Smoothing factor	Blends the previous speed with the new target on each processing tick. Larger values retain more of the previous speed.

Smoothing is tick-based, so do not interpret its factor as a fixed duration. Start with the default controls, then tune against the cadence and noise of the incoming position updates.

Loss of synchronization

If no sync applies when the selected mode cannot use its inputs:

Stall keeps running until Dead reckoning timeout elapses, then targets zero speed.
Zero immediately targets zero speed.
KeepSpeed retains the previous target indefinitely.

The Speed output still passes through smoothing. Even Zero does not necessarily make the emitted speed zero in the same tick.

Typical connection

[External position / speed / validity]
                 |
       [Timecode Synchronizer]
          |              |
        Speed        Timecode correction
          |              |
       [Playback controls of the target]

Choose the same time units on both ends of a position connection. Confirm how the target handles reverse speed and seek messages before using the patch in performance.

Source reference: score-plugin-avnd/CMakeLists.txt registers ao::TimecodeSynchronizer; its controls and algorithm are defined in 3rdparty/avendish/examples/Advanced/Utilities/TimecodeSynchronizer.hpp.

ossia