Re: [fluid-dev] synth.audio-groups and LADSPA effects

[Ceresa Jean-Jacques]

Hi,

 

>Thanks for the clarifications, all! I thought the main issue was probably an ALSA limitation, but I think I can do what I want using JACK and the information you've given me.

 

Yes, Marcus has pointed an important limitation of most "Fluidsynth audio driver" in regard to synth.audio-channels. It seems that actually most "Fluidsynth audio driver" ignore "synth.audio-channels" setting. I don't think it is host device driver limitation (ALSA on linux,  or dsound on Windows).

On any system, as far the audio device card is multi channel capable, the host device driver should expose these capabilities. Then, it is up to the "fluidsynth audio driver" to follow and use these capabilities for "synth.audio-channels" value > 1. Be able to separate the audio rendered by MIDI Channel to distinct audio device card's audio port is a very useful feature. This should simplify

the architecture of the application making use of fluisdynth library. Because of this limitation many application could use a workaround relying to multiple instance pair (synth instance + audio driver instance) which is complicated, inefficient, not flexible. I will look, to see how we could suppress this limitation.

jjc

 

> Message du 04/08/20 21:43
> De : "Bill Peterson" <albedozero@gmail.com>
> A : "FluidSynth mailing list" <fluid-dev@nongnu.org>
> Copie à : "Ceresa Jean-Jacques" <jean-jacques.ceresa@orange.fr>, "TomM." <tom.mbrt@googlemail.com>
> Objet : Re: [fluid-dev] synth.audio-groups and LADSPA effects
>
>

Thanks for the clarifications, all! I thought the main issue was probably an ALSA limitation, but I think I can do what I want using JACK and the information you've given me.
>

>

On Tue, Aug 4, 2020 at 2:33 AM Marcus Weseloh <marcus@weseloh.cc> wrote:
>

Hi,
>
> Am Di., 4. Aug. 2020 um 02:16 Uhr schrieb Ceresa Jean-Jacques
> <jean-jacques.ceresa@orange.fr>:
> > 1)The number of rendered audio output (nbr_outputs) is dependant of synth.audio-channels and synth.audio-group:
> > nbr_outputs = max(synth.audio-channels, synth.audio-groups) (default is 1).
> > These audio outputs will be played by the sound card (if it is capable to play this nbr_outputs amount of course).
>
> Please note that this is highly dependent on the audio driver used.
> AFAIK, only the jack driver supports multi-channel audio output. All
> other drivers (including alsa) can only output a single stereo signal.
>
> > [...]
> > 4) Which output, internal effects (reverb, chorus) are mapped on ?
> >
> > As Marcus already said, both internal reverb and chorus are mapped only to output 0 (because "synth.effects-groups" has a default value of 1).
> > However, if "synth.effects-groups" is set to 2,  two distinct internal instances pair (reverb + chorus) should be available on each distinct audio output (0 et 1).
>
> This also only applies only to the jack driver. Again AFAIK, for all
> other drivers (including alsa), the reverb and chorus signals are
> always rendered to the first (and only) stereo output, regardless of
> the setting of synth.effects-channels.
>
> Cheers
> Marcus
>
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