MIDI Timecode - Time Code Format

Time Code Format

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 requires 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.

Like most audiovisual timecodes such as SMPTE time code, it encodes only time of day, repeating each 24 hours. Time is given in units of hours, minutes, seconds, and frames. There may be 24, 25, or 30 frames per second.

Each component is assigned one byte:

Byte 0

0rrhhhhh: Rate (0–3) and hour (0–23).

• rr = 00: 24 frames/s
• rr = 01: 25 frames/s
• rr = 10: 29.97 frames/s (SMPTE drop-frame timecode)
• rr = 11: 30 frames/s

Byte 1

00mmmmmm: Minute (0–59)

Byte 2

00ssssss: Second (0–59)

Byte 3

000fffff: Frame (0–29, or less at lower frame rates)