Hi,
I am the lead developer of the Music Player Daemon project, and I have
written a fluidsynth plugin for it:
http://git.musicpd.org/cgit/master/mpd.git/tree/src/decoder/fluidsynth_plugin.c
There were lots of difficulties during the development, and I couldn't
solve some of them. Let me drop a load of rants:
- the API expects "char*" parameters, but I have only "const char*" -
that means I have to duplicate all strings which are passed to
fluidsynth.
- fluidsynth is undocumented.
http://www.nongnu.org/fluid/api/ lists just the prototypes
http://www.toncat.de/fluidsynth/ and
http://personales.ya.com/berarma/fluidsynth/html/ are a good start,
but so incomplete that they're mostly unusable.
Most of the time, I had to read fluidsynth's source, or the source
of applications using fluidsynth. For my purposes, there is no good
sample code.
- there is no way to tell whether the "player" has finished playing a
MIDI file - the "status" attribute is not exposed. Even the
"fluidsynth" program does not exit when the song is finished,
because it doesn't know either.
- the "player" insists on playing in real-time, all my attempts to
fill MPD's internal audio buffer as fast as possible failed, there
was only silence in the buffer after the fluid_synth_write_s16()
call. The same might be true when MPD is paused - I suspect
fluidsynth will continue playback, but havn't tried yet (wasted more
than enough time with figuring out the API). I don't want
fluidsynth to make any assumptions on the wall clock - I want to
read PCM samples out of it whenever I feel like doing so, as fast as
the CPU can handle it. Just like all the other decoder libraries.
- error handling in fluidsynth is awful. Most functions return an
undocumented "int", its meaning can only be derived from reading the
source, but I cannot grasp what's gone wrong, I cannot generate a
usable error message. Non-fatal errors (as well as fatal errors)
are printed to the log file, but the logging subsystem of fluidsynth
is not thread safe (i.e. thread aware), so I cannot use the logging
callback as a hack.
In general, libraries shouldn't log at all, they should return
good error codes/messages in some way. The application should
decide what to do when an error occurs.
- I don't want fluidsynth to create a new thread. Synthesize the MIDI
file synchronously in the thread which called the library.
Please keep me on Cc in responses, because I'm not subscribed to the
mailing list.
Max