Merging and Splitting MIDI
Merging loses track names and channel assignments, so split by channel before rebuilding tracks.
Related
Merge the two piano tracks into one, split them again, and the sustain pedal is often a single curve while one hand has lost its place.
What a merge loses
Notes, lengths and velocities survive. Track names, channel assignments, ports and controller ownership do not. If two tracks that used separate channels both land on channel 1, their program changes overwrite each other and only the last one applies. Drums make it obvious: move a drum part off the percussion channel and the kit turns into a row of pitches.
Tracks, channels, ports
A track is a container in the file, a channel is the four-bit address inside a message, and a port is a virtual cable between programs. One track can carry several channels, and one channel can span tracks. Merging usually works by track, while splitting usually works by channel, which is exactly where information disappears.
| Idea | Scope | On merge | On split |
|---|---|---|---|
| Track | Any number per file | Names and order collapse | Rename afterwards |
| Channel | Sixteen per port | Same number overwrites | Split by channel first |
| Port | Virtual cable | Often ignored | Handle each port separately |
| Controller | Bound to a channel | CC follows one channel only | Copy before splitting |
When to merge
Multiple drum microphones, octave doublings and comped takes all belong on one track. After merging, check channel numbers, the first program change and the position of the CC data. If performance detail matters, duplicate before merging and keep the original for comparison. Confirm the track no longer needs separate editing before merging it.
Splitting without loss
Split by channel first, then by pitch. Before splitting, copy sustain, expression and pitch bend onto every new track, then confirm each one starts with the right program. Rename everything instead of leaving Track 1 copy in place. A format 0 file has one track, so splitting means pulling channels out one by one and saving the result as format 1.
Failure modes
Two tracks land on the same channel number, so notes pile up and velocities scramble. A drum track merges with a melody and the keys fall outside the drum map. Only notes are split, so the pedal stays behind on the original track. Track names repeat and the mixer no longer shows which instrument is which. Save a copy before merging; guessing afterwards costs more time.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Along the same line
Sources
- MIDI 1.0 Detailed Specification, MMA, 通道消息与轨道块的定义
- Apple Logic Pro User Guide, MIDI 编辑与合并操作
- Ableton Live Reference Manual, MIDI 轨道与片段