MIDI time code

The MIDI time code, or MTC is a time code that is transmitted via MIDI to synchronize playback devices such as drum machines, sequencers, and tape machines. Basically MTC is a re-coding of the SMPTE time code standard such that SMPTE times can be transmitted via MIDI; the way it measures time is similar enough that a converter box can easily convert an incoming SMPTE time code signal into MTC or vice versa.In MTC, the time source transmits four quarter frame messages per SMPTE frame.The quarter frame messages themselves mark time, but also each one carries a part of the current SMPTE hour:minute:second:frame time value. After enough quarter frame messages have been received, the receiver can assemble the received data and discover the current absolute SMPTE time; by this method devices can achieve time synchronization from a “cold start” without any prior cueing. MTC is a considerable improvement over the older MIDI Clock message standard, which only marked time and did not have any means of sending the current time to devices for cueing purposes.