Designates the SMPTE start time (hours, minutes, seconds, frames, subframes) of the MTrk. It should be at the start of the MTrk. The hour should not be encoded with the SMPTE format as it is in MIDI Time Code. In a format 1 file, the SMPTE OFFSET must be stored with the tempo map (ie, the first MTrk), and has no meaning in any other MTrk. The ff field contains fractional frames in 100ths of a frame, even in SMPTE based MTrks which specify a different frame subdivision for delta-times (ie, different from the subframe setting in the MThd).