[fluid-dev] Some questions about Midi playback

[Sebastien Frippiat]

Hi.

I work in an entreprise in Belgium which is specialized in interactive 
multimedia solutions for museums, theme parks... We would like to have a 
good Midi support in our main software.

So I'm currently searching for a good Midi library. I need to be able to 
play Midi files and to be able to change some parameters such as tempo 
and velocity. I searched a lot and came across FluidSynth. I played a 
bit with it and managed to easily play Midi files. However I have a few 
questions about it :

- Is it possible to modify tempo such as the Midi file is playing twice 
faster than as specified in the Midi file (I tried 
fluid_player_set_midi_tempo 
<http://www.nongnu.org/fluid/api/midi_8h.html#a33> but it didn't worked 
well for this purpose) ? I managed to do it by modifying the source code 
: it is quite easy to multiply/divide the tempo when receiving tempo 
events. I hard-coded the multiplier to do the test. I would gladly write 
a clean way to do it (by adding something like 
fluid_player_set_midi_tempo_multiplier by example) if it would interest 
someone. However I would like to know if there is clean way to do it 
without modify the source code of FluidSynth.
- Same question for the velocity (easy to change it when receiving 
NoteOn and NoteOff events).

Besides, is it possible, when reading a Midi file, not to send the data 
to the synthetizer but instead forward the Midi messages to a Midi 
device ? I guess it would require me to have something like a callback 
when reading the file but I didn't find it. Again, I think it would be 
pretty easy to add it to the library. I searched the doc and the source 
code for informations about the router but it seems it is only used for 
Midi input (am I wrong ?). It would be useful to add something like 
routers when playing Midi file (and therefore consider Midi file and 
Midi file player as Midi input).

Does anybody have remarks / recommendations / answers ?

Thank you very much,
Sebastien Frippiat