MIDIopsy Help

What is MIDIopsy?

MIDIopsy is used to view, edit, and play MIDI files. The user is assumed to be familiar with the standard MIDI file format. (For more information, see Online Resources at the bottom of this page.)

When a file is open, its contents are shown as rows in a grid/list view. Chunks are separated by empty rows (which cannot be selected). Each row within a track chunk represents an MTrk event.

The leftmost column contains the binary contents of the file (in hexadecimal format), while the other columns contain user-friendly comments. (Note that Total Time is not stored in the file; it is calculated from Delta-time.) Column widths can be adjusted as desired.

Open an existing MIDI file

• Click Open (or press Ctrl+O).
• If no file is open, a file that has been opened recently can be reopened directly. Under Open Recent, simply click the file path (or press the corresponding number key).

Create a new MIDI file

1. Click New (or press Ctrl+N).
2. Specify a File name.
3. Specify the Format.
4. If the format is 1 (one or more simultaneous tracks) or 2 (one or more independent tracks), specify the Number of tracks.
5. Under Delta-time division, check either Metrical time or Time-code-based time.
   • For metrical time, specify the Ticks per quarter note.
   • For time-code-based time, specify the SMPTE format (frames per second) and Resolution (ticks per frame).
6. Click OK (or press Enter). The new file is shown with a new MThd (header) chunk created as specified, along with the specified number of MTrk (track) chunks, each with an End of Track meta-event.

Save a MIDI file

• To use the file's current name, click Save (or press Ctrl+S). (For a new file being saved for the first time, this is equivalent to Save As.)
• To use a different name, click Save As (or press Ctrl+Shift+S).

Close an open MIDI file

• Click Close (or press Ctrl+F4).
• After the file is closed, a list of recently opened files is shown under Open Recent. Any of these files can be reopened directly (see Open an existing MIDI file above). Simply click the file path (or press the corresponding number key).

Edit a MIDI file

Warning: MIDI file editing is for expert users only. If not done correctly, it could result in data corruption, making the file unusable. Proceed at your own risk!

• To create a new track (MTrk chunk), position the cursor in the chunk before which you want the new track to appear, and click Track (or press Alt+K). A new MTrk chunk (with an End of Track meta-event) should appear after the chunk containing the selected row.
• To create a new MTrk event, position the cursor on the row before which you want the new event to appear, click the appropriate button and provide the required input (see table below). The new event should appear after the selected row. Note:
  • Events cannot be created within the header (MThd) chunk.
  • Delta-time is required for all events.

• To edit the properties of an event or the file header (the data of the MThd chunk), position the cursor on the item you want to edit, click Properties (or press F4) and edit the properties as desired. Note:
  • Once an item is created, some properties cannot be edited.
  • The properties (i.e., the first row) of a chunk cannot be edited.
• To cut an event (so it can be pasted elsewhere), position the cursor on the event you want to cut, and click Cut (or press Ctrl+X).
• To copy an event (so it can be pasted elsewhere), position the cursor on the event you want to copy, and click Copy (or press Ctrl+C).
• To paste the event you have cut or copied, position the cursor on the row before which you want the event to appear, and click Paste (or press Ctrl+V). The event should appear after the selected row.
• To delete an event, position the cursor on the event you want to delete, and click Delete (or press Del).
• To delete an entire chunk (e.g., a track), position the cursor on the first row of the chunk, and click Delete (or press Del). You should receive a warning that the entire chunk will be deleted.
• Note that some items (such as the header chunk) are considered essential and may not be deleted.

MIDI file navigation

• To move the cursor to a specific place within the file, click Go To (or press Ctrl+G), specify a Track and either a Total time (in ticks) or a Position (hh:mm:ss), and click OK (or press Enter).

MIDI file playback

When a MIDI file is opened or saved, MIDIopsy also loads it for media playback. (A new file must be saved before it can be played.) If the file has not been saved since it was last edited, it must be saved in order to play the current version (with the most recent edits).

Playback starts at the indicated Starting Position (SP), which can be set to any position within the indicated Duration. When a file is loaded for playback, its Starting Position defaults to 00:00:00, and its Duration is determined. During playback, the current Position is updated.

• To start playing the file, click Play (or press F5). To stop playback, click Stop (or press F5 again).
• To reset the Starting Position back to 00:00:00, click Reset SP (or press F6). The starting position should flash orange to indicate that it has been reset.
• To "synchronize" the Starting Position (i.e., set it equal to the current Position), click Sync SP (or press F7). The starting position should flash yellow to indicate that it has been synchronized.

Keyboard Shortcuts

MIDI Reference

For more details on MIDI and MIDI specifications, please visit https://www.midi.org/.

Online Resources

• MIDIopsy Home Page
• The MIDI Association
• Standard MIDI File (SMF) Format

© 2018-20 Jeffrey Paul Bourdier