| 词条 | MIDI beat clock |
| 释义 |
MIDI beat clock (also known as MIDI timing clock or simply MIDI clock) is a clock signal that is broadcast via MIDI to ensure that several MIDI-enabled devices such as a synthesizer or music sequencer stay in synchronization. It is not MIDI timecode. Unlike MIDI timecode, the MIDI beat clock is tempo-dependent. Clock events are sent at a rate of 24 ppqn (pulses per quarter note). Those pulses are used to maintain a synchronized tempo for synthesizers that have BPM-dependent voices and also for arpeggiator synchronization. Location information can be specified using MIDI Song Position Pointer (SPP, see below), although many simple MIDI devices ignore this message. Because of limitations in MIDI and synthesizers, devices driven by MIDI beat clock are often subject to clock drift.{{Citation needed|date=October 2017}} MIDI beat clock defines the following real time messages:
MIDI also specifies a System Common message called Song Position Pointer (SPP). SPP can be used in conjunction with the above realtime messages for complete sync. This message consists of 3 bytes; a status byte (decimal 242, hex 0xF2), followed by two 7-bit data bytes (least significant byte first) forming a 14-bit value which specifies the number of "MIDI beats" (1 MIDI beat = a 16th note = 6 clock pulses) since the start of the song. This message only needs to be sent once if a jump to a different position in the song is needed. Thereafter only realtime clock messages need to be sent to advance the song position one tick at a time. See also
External links
4 : Encodings|MIDI standards|MIDI|Synchronization |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。