Re: [fluid-dev] Some questions about Midi playback

[Sebastien Frippiat]

Hi again.

> - 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).

As I need to progress on this, I went on my way to modify fluidsynth 
source code. You'll find attached a little patch to apply my 
modifications. Just cd to the fluidsynth-1.0.7 directory, copy the patch 
file and run the following :
patch -u -i fluidsynth-tempo-velocity.patch -p 1

Then you can ./configure and make the library.

> 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).
Ok, as I worked a bit within the source code and I played a bit with it, 
I have some more remarks about what I'm trying to do. I know that 
fluidsynth is about playing Midi files / data through a software 
synthetizer. However, I'm more interested in using the Midi card to do 
that and to be able to use other Midi renderering devices. I'm not a 
music expert but I think that modifying the fluid_midi_send_event (in 
fluid_midi.c) function could work.

Any ideas, remarks ? (please...)

Thank you,
Sebastien Frippiat