Import troubleshooting
Common MIDI file errors
A MIDI file can open in one program and fail in another without either program being obviously wrong. The event data may be malformed, the timing may be unsupported, or the file may contain a value that a destination cannot map. This guide lists the problems worth checking first.
What matters most
- A valid header does not guarantee valid events.
- Type 2 and SMPTE timing need special handling.
- One End of Track event per track is the safe default.
- A structural checker cannot predict every instrument mapping.
Header and timing problems
A Standard MIDI File starts with an MThd header. If the header is missing, truncated, or declares a track count that does not match the readable tracks, the file is malformed. A parser may still salvage something, but the result should not be trusted.
Type 2 files contain independent sequences rather than one shared timeline. SMPTE time division expresses time in frames and ticks instead of PPQ. EditMIDI rejects both with a specific message because it cannot safely represent them as one editable piano-roll timeline.
Channel, note, and velocity ranges
MIDI channels are zero-based in the file data and usually shown as 1–16 in a DAW. A channel value outside that range is invalid. A note number outside 0–127 is invalid, and a velocity outside 0–127 is invalid. A checker should point to the track and the event, not just say “bad file.”
Channel 10 is not an error. It is the conventional percussion channel in General MIDI. A file that sounds like drums on channel 10 is behaving normally; a melodic part accidentally assigned to channel 10 is a routing problem.
End of Track and track structure
Each track should normally contain one End of Track event. Zero events can leave a parser guessing where the track ends; several events can confuse a strict importer. EditMIDI warns when a track does not contain exactly one.
Track names, program changes, and controllers are optional. Their absence is not automatically an error, but it can explain why a file sounds different from the source. A missing program change may leave the destination on its previous patch.
Event and track limits
A file can be structurally valid and still be too large for a browser editor. EditMIDI supports up to 5 MB, 64 tracks, and 20,000 events. A dense orchestral file or a long generated export may exceed those limits even though a desktop DAW can open it.
If a file is too large, split it by section or remove unused tracks in a DAW before bringing it into the browser. Do not assume a failed import means the file is corrupt; it may simply be outside the tool’s supported range.
Tempo, duplicate notes, and silent damage
Competing tempo events can make a merged file play at the wrong speed even though every note is within range. Duplicate notes can make a part sound louder or phasey without producing an error. A note with a zero-length start and end is another common artifact of a bad edit or conversion.
The piano roll is the fastest way to see duplicates and collapsed notes. The file checker handles structure; your ear and the visual timeline handle the musical damage. Use both before exporting.
A short import checklist
Check the SMF type and PPQ. Confirm the track count and channels. Look for range errors and End of Track warnings. Inspect the tempo map. Audition the file in the destination instrument. If it still fails, compare the report with the error message from the DAW instead of changing random events.
Keep the original file and export a corrected copy. A clear error message plus a structural report is much easier to act on than a series of blind edits. When the checker reports no errors, the remaining problem is usually a mapping, instrument, or destination-specific issue.
How to report a broken file
When a file fails in a DAW, record the exact error message, the program and version, and the step that failed. Note whether the file opens in another player. That information is more useful than a screenshot of a generic import dialog.
Share a minimal sample only when you have the rights to do so and the recipient has explained how it will be handled. A structural report plus the exact error often identifies the problem without sending the whole arrangement. Keep the original file unchanged while you investigate.
- Record the exact error and the app version.
- Test the file in a second player before editing it.
- Share a minimal sample only with permission.
A final verification pass
After fixing a structural problem, run the checker again and compare the report with the first one. Confirm that the error count dropped and that no new warning appeared. Then open the file in the destination and play the section that failed before.
A file that imports successfully is not automatically musically correct. Check the tempo, the first note, and the track routing. Structural validation and musical validation are separate steps, and a good workflow uses both.
- Re-run the checker after every fix.
- Compare the new report with the previous one.
- Audition the section that failed before exporting.
Questions and answers
Why does a MIDI file open in one DAW but not another?
Importers differ in how strict they are about malformed events, Type 2 sequences, SMPTE timing, and track structure. A file can be readable by one program and rejected by another.
What is an End of Track error?
A track should normally end with one End of Track meta event. Missing or duplicated events can confuse strict importers. EditMIDI reports the count as a warning.
Can the checker repair a file automatically?
No. It reports structure and issues. Use the editor to fix the event, remove a duplicate, change a channel, or rewrite the tempo map, then export a new file.
Is channel 10 always drums?
In General MIDI convention, channel 10 is percussion. A file can use it differently, but many instruments and DAWs will treat it as a drum channel. Check the track’s intended role before moving notes off it.
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