About RMIDI

About RMIDI

SpessaSynth supports exporting to RMIDI, which is essentially MIDI + SF2 as a single file. As there's no specification on this type of RMIDI available, this page can serve as an "unofficial documentation" to this format.

This version of RMIDI does not use DLS and has been created (I think) by Falcosoft MidiPlayer6. I'm currently in contact with Falco and we're working on improving this format.

General RIFF structure

The following describes how is the file formed:

RIFF chunk (the main chunk)

• RMID ASCII string
• data chunk
• • The complete MIDI file (MThd, MTrk, etc)
• Optional LIST chunk: metadata of the file. Very similar to SF2's chunk
• • INFO ASCII string
• • Inner chunks described here
• RIFF chunk - the complete soundfont binary. Note that the first 4 bytes of the chunk should form sfbk, like in a normal soundfont, to indicate that this is an SF2 soundfont and not a DLS one. SF3 compressed soundfonts are allowed.

If any other chunks are encountered, they should be ignored.

The INFO chunk

The info chunk describes the metadata of the file. Rules:

• If any other RIFF chunks are encountered within the INFO chunk, they should be ignored.
• The chunk size has to be even. If the text length is odd, the text is padded with a 0 terminator byte.

It has the following fields (all optional):

• Optional INAM chunk: song name. Preferably the same as the MIDI file.
• Optional ICOP chunk: copyright. String of any length.
• Optional ICRD chunk: creation date, string.
• Optional ICMT chunk: comment/description. String of any length.
• Optional IENG chunk: the engineer who worked on the file (the creator). String of any length.
• Optional ISFT chunk: software used to create the file. String of any length.
• Optional IENC chunk: the encoding to use for other info chunks, string. (For example utf-8). Not case sensitive, but lowercase is preffered. If not specified, ASCII is assumed. Note that this field MUST use ASCII.
• Optional DBNK chunk: see this

It's up to the software to determine which is the name of the file (track name in MIDI or INAM chunk) although INAM chunk is preffered.

The DBNK Chunk

The DBNK chunk is an optional RIFF chunk for the RMID INFO List. It always has a length of 2 and the 2 data bytes form a 16-bit little-endian offset for the soundfont banks.

Currently the boundaries are: min: 0 and max: 127. The other byte is reserved for future use.

All banks can be offset in the MIDI file and the soundfont. For example, offset of 1 means that every bank in the soundfont is incremented by 1. For drums the bank is 1. For XG, the behavior is not yet defined.

Note that the MIDI must use valid banks and presets as MP6 will fallback to the loaded soundfont instead of defaulting to preset 0 of the embedded soundfont. The behavior of missing preset requested in the MIDI sequence is undefined. Also the system cannot be GM since bank is ignored there. Either GS or XG are valid. This requires sanitizing the midi and putting either GS or XG on at the start.

If no DBNK is specified, offset of 1 is assumed by default.

Note that this should be reflected in the MIDI file itself:

• If DBNK is 1 and MIDI wants to use preset 001:080, it should call bank select of 2 instead of 1.
• If DBNK is 0, no offset is applied and the MIDI is unchanged.

If DBNK is 0, the system can be GM as the soundfont gets loaded at bank 0.

Bank offset

In MidiPlayer6, all banks seem to be offset by 1 by default. It can be set to 0 by altering the Real Time Loaded SF2 Default Bank value to 0 in Device Settings dialog. In the future, it will also be affected by the DBNK chunk described above. This means that to get bank 1, send bank select 2 in the embedded MIDI, etc. Using bank 0 in MP6 leads to the loaded soundfont being used, not the embedded one. For drums the bank is 1 in XG.

Program and bank Correction

The MIDI must use valid banks and presets as MP6 will fallback to the loaded soundfont instead of defaulting to preset 0 of the embedded soundfont. Also the system cannot be GM since bank is ignored there. Either GS or XG are valid. This requires sanitizing the midi and putting either GS or XG on at the start.