Re: [fluid-dev] fluid_sequencer_send_at ignoring time when not using an audio driver

[Raja Mukherji]

On Sun 17 Jun 2012 13:02:39 IST, Pedro Lopez-Cabanillas wrote:
> On Thursday 14 June 2012, Raja Mukherji wrote:
> > I'm not sure if I'm doing something wrong but it seems as though
> > fluid_sequencer_send_at is ignoring the time parameter.
> >
> > I'm trying to use fluid_synth_write_float to render music to a buffer
> > that I can then encode and stream to a browser. Hence realtime
> > rendering is not important, rather rendering as fast as possible is
> > desired.
> > I've created a sequencer using new_fluid_sequencer2(0) so it's not
> > using the system timer. I'm trying to render in 3 second blocks
> > (arbitrary for now, I've tried smaller and longer blocks). For each
> > block, I create and send all the events for that block. Then I call
> > fluid_synth_write_float. It seems that the tick value of the sequencer
> > does not change in a manner consistent with the call to
> > fluid_synth_write_float so I am adjusting the times for all events in
> > a block by the value returned by fluid_sequencer_get_tick and using
> > relative times (so the last parameter to fluid_sequencer_send_at is
> > false). I have tried using absolute times too, with no difference.
>
> I can't reproduce your problem. Attached is a slightly version of our
> fluidsynth_metronome program that is distributed in the doc/ folder of
> FluidSynth:
> http://fluidsynth.sourceforge.net/api/fluidsynth__metronome.c-example.html
>
> Instead of using an audio driver, this modified program renders 10 bars of
> the metronome pattern to a wav disk file. It uses absolute tick times, like
> the original sample program. The result has all beats where they should be.
>
> Regards,
> Pedro

Thanks for your reply. I had originally used this this method with the 
sequencer callback and it worked fine, as it does in your example. The 
problem is that this method does suit the rest of the application which 
is processing events for any number of synths and for lv2 and other 
filters (basically a modular synth application). So I'm not using 
fluid_sequencer_register_client and a callback to add new events, 
instead I'm adding events using fluid_sequencer_send_at and then 
directly calling fluid_synth_write_float in effectively one large loop.

The code for the loop is spread over several files, but I've attached 
pseudo-code showing the effective loop.

I have found a working solution for now, by writing my own simple 
sequencer (which interleaves calls to fluid_synth_write_float with 
direct calls to fluid_synth_noteon, fluid_synth_noteoff, etc).

Regards,
Raja

renderloop.c
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