Re: [fluid-dev] sequencer / synth bug ?

[Mihail Zenkov]

Sorry for long answer.

> you mean that the 1ms accuracy of fluid may be the cause of the  
> problem ? But the noteoffs are programmed about 7 ms after the  
> noteons...

It just imho. What Josh think about this?

When i run fluidsynth with -v i see something like this:
fluidsynth: noteon      9       70      52      00000   50.241  810643.938      
0.000   0
fluidsynth: noteon      9       70      52      00000   50.241  810643.938      
0.000   1
fluidsynth: noteoff     9       70      0       00000   50.245  810644.062      
0.004   2
fluidsynth: noteoff     9       70      0       00000   50.245  810644.062      
0.004   2
fluidsynth: prog        9       128     0
fluidsynth: noteon      9       70      52      00001   50.493  810646.250      
0.000   0
fluidsynth: noteon      9       70      52      00001   50.493  810646.250      
0.000   1
fluidsynth: noteoff     9       70      0       00001   50.499  810646.312      
0.006   2
fluidsynth: noteoff     9       70      0       00001   50.499  810646.312      
0.006   2
fluidsynth: pitchb      9       8192
fluidsynth: cc  9       7       110
fluidsynth: noteon      9       70      52      00002   50.807  810648.688      
0.000   0
fluidsynth: noteon      9       70      52      00002   50.807  810648.688      
0.000   1
fluidsynth: noteoff     9       70      0       00002   50.807  810648.688      
0.000   2
fluidsynth: noteoff     9       70      0       00002   50.807  810648.688      
0.000   2
fluidsynth: cc  9       10      64
fluidsynth: cc  9       91      40
fluidsynth: cc  9       93      0
fluidsynth: noteon      9       70      52      00003   54.265  810653.250      
0.000   0
fluidsynth: noteon      9       70      52      00003   54.265  810653.250      
0.000   1
fluidsynth: noteoff     9       70      0       00003   54.281  810653.375      
0.016   2
fluidsynth: noteoff     9       70      0       00003   54.281  810653.375      
0.016   2

It first four notes, firs and second play fine. Third note not play at
all. As we can see, noteoff performed in same time as noteoff. Fourth
note play, but sounds bad.

> What do you mena by 'low latency tuning' ? Large playback buffers ?

Small buffer, linux kernel 2.6.21 compiled with "Preemption Model
Low-Latency Desktop" and "Timer frequency" = 1000 hz.

> One thing to note is that the midifile playing feature of fluidsynth  
> does not use the fluid sequencer. As the problem happens with boths  
> ways (my fluidXtra ises the sequencer, and the standard midifile  
> playback does not), it means that it is related to the fluid  
> synthesis itself, not a problem of accuracy in the sequencer. This  
> rules out the sequencer as a cause of the problem, which is good to  
> know.
> 
> Your points about aplaymidi loosing notes too, and well as rosegardan  
> (even though it looses less notes) is interesting. It means that this  
> midi file is touching some midi playing general limit.

Rosegarden have very low latency in spirit and work with fluidsynth
much better. It adduce me to think - 1ms not enough.

> Thanks for your help, I'm really try to understand and fix this problem,

Thanks for report :)