Adding custom music
PWADs can include music lumps for custom music when played. Originally, these lumps were encoded in the MUS format. WAD editors need to convert between that and a format used by music authoring tools, such as MIDI.
Since v1.5, Doom has been able to read standard format MIDI files for music, as long as they are no larger than 64kb. The Windows 95 version of Doom, Doom95, however does not have the ability to play MIDI files.
Many modern ports will accept MIDI lumps without any limitation.
To add music to a WAD you will need:
- If your map occupies the MAP01 slot, you will have to rename the MIDI file to D_RUNNIN for it to work properly. See music for a list of names used on other map slots.
- Open your map in SLADE 3. Drag and drop your MIDI file in the list of entries, but make sure not to insert it between map lumps or *_START/*_END markers.
 Creating MIDI files
There are several sequencers that can create MIDI files. Just search for MIDI sequencer and you'll most likely find one that suites your needs.
When creating a MIDI file make sure that no notes stretch out beyond the end of the MIDI file, or else your song will end with a silent bar of music.
 MUS format
- Doom MUS format uses 9 channels apart from MIDI's 16 channels using channel 1-8 for sounds and channel 9 for drums.
- Each channel can only play 1 note at the time, so if you want to add a chord then you have to set 3 channels to the same patch and split the notes up that way.
- MUS format uses the same MIDI patch layout as in General MIDI.