Re: [fluid-dev] Re : Re: Re : no effects applied using multiple stereo channels

[jean-jacques.ceresa]

Le 10/04/2015 15:56, Tom M. a écrit :
> followed by starting fluidsynth:
>
> fluidsynth -a jack -L 3 my.sf2
>
> and then capturing the output of fluidsynth. All midi channels were
> clearly hearable, again, reverb was missing.
>
> Restarting fluidsynth changing -L to 1 and reverb works fine again.
> Note that I didn't changed jack in any way.
This Jack behavior is a mistery for me.  But one think is sure, by 
reading the code in the Mixer we can see that:
1) The setting - L 3 set the number of buffer (buff_count = 3) on Mixer 
output .
2) And we can see that the mapping of Voices to the buffers depends of 
this number (buff_count)
and the MIDI_Channel_number of the voice. As This:
Buffer index = 2 x ( MIDI_Channel_number modulo buff_count).

So Voice MIDI Channel 0,3,6... go to Buffer 0
     Voice MIDI Channel 1,4,7... go to Buffer 1
     Voice MIDI Channel 2,5,8... go to Buffer 2

3)At the same time alls the voices output are mixed to the Reberb input 
buffer.
Than, after reverb processing, the Reverb output is mixed to the Buffer 
0 (this is the default Mix mode for reverb).
This is the end of Mixer processing with resulting audio in Buffer 0, 1 
and 2.

4)Now theses buffers are the input buffer for any Audio Driver used 
(Jack,Dsound,...).
Really i don't know how Jack Driver handle theses input buffers, but 
this buffers are passed to Jack Driver by the Audio rendering function.
If you can heard Voice MIDI Channel 0,3,6 you should heard reberb .
If you cannot heard Reverb , i don't understand how you can hear Voice 
MIDI Channel 0,3,6.

It seems there is something wrong beetween the Audio Rendering function 
and Jack audio driver ? Please ask David H.

> Another thing that strikes me: There is an option called
> audio.jack.multi. The documentation says:
>
> "If 'yes' then create separate output ports for reverb and chorus effects."

The documentation is here 
http://fluidsynth.sourceforge.net/api/index.html#CreatingAudioDriver
I am sorry, but i read only this:

If 1 (TRUE), then multi-channel Jack output will be enabled if 
synth.audio-channels is greater than 1.

jjc