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MIDI timecode
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<h2 id="time-code-format">Time code format</h2> <p>The MIDI time code is 32 bits long, of which 24 are used, while 8 bits are unused and always zero. Because the full-time code messages require that the most significant bits of each byte are zero (valid MIDI data bytes), there are really only 28 available bits and 4 spare bits. </p><p>Like most audiovisual timecodes such as <a href="/facts/SMPTE_time_code/atPpXSrI">SMPTE time code</a>, it encodes only time of day, repeating each 24 hours. Time is given in units of hours, minutes, seconds, and <a href="/facts/Film_frame/27Uqo8WN">frames</a>. There may be 24, 25, or 30 frames per second. </p><p>Unlike most other timecodes, the components are encoded in straight binary, not <a href="/facts/Binary-coded_decimal/dWTaE7ES">binary-coded decimal</a>. </p><p>Each component is assigned one byte: </p> Byte 0 0rrhhhhh: Rate (0–3) and hour (0–23). <ul><li>rr = 00: 24 frames/s</li> <li>rr = 01: 25 frames/s</li> <li>rr = 10: 29.97 frames/s (SMPTE <a href="/facts/Drop-frame_timecode/atPpXSrI">drop-frame timecode</a>)</li> <li>rr = 11: 30 frames/s</li></ul> Byte 1 00mmmmmm: Minute (0–59) Byte 2 00ssssss: Second (0–59) Byte 3 000fffff: Frame (0–29, or less at lower <a href="/facts/Frame_rate/sbRkc9xa">frame rates</a>) <h3>Full time code</h3> <p>When there is a jump in the time code, a single full-time code is sent to synchronize attached equipment. This takes the form of a special global system exclusive message: </p> F0 7F 7F 01 01 hh mm ss ff F7 <p>The manufacturer ID of 7F indicates a real-time universal message, the channel of 7F indicates it is a global broadcast. The following ID of 01 identifies this is a time code type message, and the second 01 indicates it is a full-time code message. The 4 bytes of time code follow. Although MIDI is generally little-endian, the 4 time code bytes follow in big-endian order, followed by a F7 "end of exclusive" byte. </p><p>After a jump, the time clock stops until the first following quarter-frame message is received. </p> <h3>Quarter-frame messages</h3> <p>When the time is running continuously, the 32-bit time code is broken into 8 4-bit pieces, and one piece is transmitted each quarter frame. I.e. 96—120 times per second, depending on the frame rate. Since it takes eight quarter frames for a complete time code message, the complete SMPTE time is updated every two frames. A quarter-frame message consists of a status byte of 0xF1, followed by a single 7-bit data value: 3 bits to identify the piece, and 4 bits of partial time code. When time is running forward, the piece numbers increment from 0–7; with the time that piece 0 is transmitted is the coded instant, and the remaining pieces are transmitted later. </p><p>If the MIDI data stream is being rewound, the piece numbers count backward. Again, piece 0 is transmitted at the coded moment. </p><p>The time code is divided little-endian as follows: </p> MIDI time code pieces<table><tbody><tr><th>Piece #</th><th>Data byte</th><th>Significance</th></tr><tr><th>0</th><td>0000 ffff</td><td>Frame number lsbits</td></tr><tr><th>1</th><td>0001 000f</td><td>Frame number msbit</td></tr><tr><th>2</th><td>0010 ssss</td><td>Second lsbits</td></tr><tr><th>3</th><td>0011 00ss</td><td>Second msbits</td></tr><tr><th>4</th><td>0100 mmmm</td><td>Minute lsbits</td></tr><tr><th>5</th><td>0101 00mm</td><td>Minute msbits</td></tr><tr><th>6</th><td>0110 hhhh</td><td>Hour lsbits</td></tr><tr><th>7</th><td>0111 0rrh</td><td>Rate and hour msbit</td></tr></tbody></table> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/AES-EBU_embedded_timecode/Il4EdVYj">AES-EBU embedded timecode</a></li> <li><a href="/facts/Burnt-in_timecode/3TVzDDkR">Burnt-in timecode</a></li> <li><a href="/facts/CTL_timecode/r8ru20WI">CTL timecode</a></li> <li><a href="/facts/DIN_sync/5yB4HEog">DIN sync</a></li> <li><a href="/facts/Linear_timecode/sgANXpwa">Linear timecode</a></li> <li><a href="/facts/MIDI_beat_clock/ep1kPcYM">MIDI beat clock</a></li> <li><a href="/facts/Rewritable_consumer_timecode/56KgEsd5">Rewritable consumer timecode</a></li> <li><a href="/facts/Vertical_interval_timecode/LILY2Atq">Vertical interval timecode</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://web.archive.org/web/20120212181214/http://home.roadrunner.com/~jgglatt/tech/mtc.htm">MIDI Time Code information</a></li> <li><a href="https://web.archive.org/web/20110629053759/http://web.media.mit.edu/~meyers/mcgill/multimedia/senior_project/MTC.html">MIDI time code specification</a> 12 Feb 1987</li> <li><a href="http://www.somascape.org/midi/tech/spec.html#syscommsgs">Guide to the MIDI Software Specification</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"SMPTE & MTC (MIDI Time Code)". www.soundonsound.com. Retrieved 2024-11-29. <a href="https://www.soundonsound.com/techniques/smpte-mtc-midi-time-code" target="_blank">https://www.soundonsound.com/techniques/smpte-mtc-midi-time-code</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"MIDI Time Code and MIDI Clock Explained". dummies. Retrieved 2024-11-29. <a href="https://www.dummies.com/article/technology/software/music-recording-software/general-music-recording-software/midi-time-code-and-midi-clock-explained-179973/" target="_blank">https://www.dummies.com/article/technology/software/music-recording-software/general-music-recording-software/midi-time-code-and-midi-clock-explained-179973/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Schütte, Benjamin; Bachmann, Cristina. "Timecode Standards". archive.steinberg.help. Retrieved 2024-11-29. <a href="https://archive.steinberg.help/nuendo/v10/en/cubase_nuendo/topics/synchronization/synchronization_timecode_standards_c.html" target="_blank">https://archive.steinberg.help/nuendo/v10/en/cubase_nuendo/topics/synchronization/synchronization_timecode_standards_c.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> </ol>