# Talk:MUS

The developers of the format were given to me by John Romero himself. --TheAlmightyGuru 07:25, 14 December 2010 (MST)

Interestingly, Dave Taylor credits Paul Radek, who was a guy Romero didn't like. --Gez 15:59, 25 February 2012 (MST)

## Technical questions

That most MUS files run at 140Hz, apart from Raptor which should be run at 70Hz. You modified the MUS files to run at 140Hz instead. I'm trying to modify our mus2midi to support changing the frequencies and need some help. Can you help me through this logic? From my understanding, 140Hz is or 8400 beats per second (BPS) which translates to 140 (BPM). Am I right so far?

PPQN (aka Division) = 96 (for example) MSPM – microseconds per minute = 60 000 000 BPM – beats per minute MPQN – microseconds per quaternote BPM = MSPM / MPQN MPQN = MSPM / BPM

one quarter note period is: MPQN = 60 000 000/140BPM = ~428571.4 microseconds

1 tick = MPQN/1000000/PPQN = 428571/1000000/96 = ~0.004464286 Hz

one full quarter note duration (96 * 1 tick = 96 * 0.004464286 Hz = ~428571.4 microseconds = 0,4s)

Now... Id's official mus2midi has a Division (PPQN) of 89 and a Tempo (MPQN) of 1745673 BPM (Hz) = MSPM / MPQN = 60000000 / 1745673 = 34.37

Doom and Doom2's Hz is 34.37

Does this make sense, or do I have it totally wrong?

Here is their source: https://github.com/id-Software/DOOM-3-BFG/blob/master/doomclassic/doom/mus2midi.cpp // microseconds per quarter note(yikes) Midi_UpdateBytesWritten(&bytes_written, 7, *len); out = Midi_WriteTempo(out, 0x001aa309);