Synchronization - What is a timecode?

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A time code is a sequence of data that indicates time references. There are many kinds of time codes, the following are the most important ones:

  • SMPTE: Society of Motion Picture and Television Engineers

  • MTC: MIDI Time Code

  • MIDI Clock

  • DINSYNC

  • FSK: Frequency Shift Keying

  • Black Burst

The first three are undoubtedly the most widespread (in actual fact the third one is part of the second one's specifications) and shall be described in detail in the next section. Here's just a brief description of the others:

FSK: this time code sends information regarding the rhythm only (similar to a clock pulse generator) and not regarding time (minutes, seconds).

Black Burst: pulse generator with very accurate timing. This brings jittering, that are impulses sent at slightly different time intervals, down to a minimum. This signal is often used as a reference point for all the machines.

The following is a list of some of the most commonly used interfaces for synchronization signals:

  • AES/EBU: Audio Engineering Society/European Broadcasting Union.

    This is an interface, not a time code, through which clock pulses can travel in between digital equipment [22 ]. Two XLR [XLR ] connectors are used in this case.

  • S/PDIF: Sony/Philips Digital Interface

    S/PDIF: Timing protocol used with low-cost or semi-professional equipment.

Let's divide the different time codes into two categories:

  • Those that depend on rhythm (measured in bpm[23 ]): in this case the time code transports information regarding rhythm only and doesn't contain any time reference.

  • Those that rely on time: in this case the time code contains all the necessary time information, such as: hours, minutes, seconds.



[22 ] Clock pulses are impulses generated at constant time-intervals by an appropriate timing-circuit.

[23 ] bmp stands for beats per minute.