in reply to building a "realtime" software synth

What exactly does not work?

I'm having very nice results with Audio::Play for playing sounds.

As for real time audio manipulation, I think you'd have to use PDL for anything complicated because of performance issues.

Also, (shameless plug here): Have you tried Audio::LADSPA? It uses ladspa plugins to do most of the real processing work, so it should be loads faster than pure perl. I'm not sure if any of the plugins can be compiled for win32, but it might be worth trying.

From the docs for Audio::LADSPA::Network 

           use Audio::LADSPA::Network;
           use Audio::LADSPA::Plugin::Play;

           my $net = Audio::LADSPA::Network->new();
           my $sine = $net->add_plugin( label => 'sine_fcac' );
           my $delay = $net->add_plugin( label => 'delay_5s' );
           my $play = $net->add_plugin('Audio::LADSPA::Plugin::Play');

           $net->connect($sine,'Output',$delay,'Input');
           $net->connect($delay,'Output',$play,'Input');

           $sine->set('Frequency (Hz)' => 440); # set freq
           $sine->set(Amplitude => 1);   # set amp

           $delay->set('Delay (Seconds)' => 1); # 1 sec delay
           $delay->set('Dry/Wet Balance' => 0.2); # balance - 0.2

           for ( 0 .. 100 ) {
               $net->run(100);
           }
           $sine->set(Amplitude => 0); #just delay from now
           for ( 0 .. 500 ) {
               $net->run(100);
           }

[download]
There are plugins available that do filtering, delays, reverbs, oscillators etc. For instance in the CMT library

Good luck
Joost.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

Replies are listed 'Best First'.
Re^2: building a "realtime" software synth
by b4e (Sexton) on Jul 20, 2004 at 15:26 UTC
    thanks for your quick reply.
    i've already tried to use Audio::LADSPA, but for some reason it does not work on my machine...
    maybe i was a bit too vague in my original question.
    what i want is that everytime a new sample is generated, ie every time 
            my $v2 = sin($counter/2*3.14) * 128 + 128;

        $data2 .= pack("c", $v2);

    [download]
    generates new data, this data should be played by the soundcard.
    this way, by including additional manipulations on $v2 using variables send to the subroutine by moving a scale-widget, the sound should change.
    i also would like to program the filters, fx, etc myself (that is, if i am able to do so...)
[reply]
[d/l]
      Hmmm. I know for a fact that Audio::Play (should you decide to use it) uses floats for sample data and most pcm output hardware uses 16-bit words per sample. Your code assumes its 8-bits.

      It's also probably more efficient to generate an @array of data first (say 100 samples) and then pack() it into a string and write it (Audio::Play can do this for you): 

      #!/usr/bin/perl -w
use strict;
use Audio::Play;
use Audio::Data;

my $player = Audio::Play->new();
while (1) {
    my $audio = Audio::Data->new( rate => 44100 );
    my @samples = map { sin ( 2 * 3.14 * $_ / 100 ) / 8 } 0 .. 99;  # 
+generate 100 samples as perl numbers
    $audio->data(@samples); # will pack() samples into floats
    $player->play($audio);
}

      [download]
      This works perfectly on my machine.

      Update:

      To clarify: you really don't want to calculate and then play each sample seperately. It's incredibly inefficient so even most C - based softsynths don't do that.

      What you want is a low latency between dragging a slider, and hearing the sound change. IMHO checking the slider state once for every 100 samples is enough:

      Say you're running at 44100 Hz (normal CD sample rate), then playing 100 samples takes 100/44100 =~ 0.0023 seconds. That's probably fast enough for anything except really exact keyboard input, provided you don't have to sync your ouput with audio streams generated from outside your machine.

      So, what you'd do is (pseudocode): 

      while (1) {
  check_for_input();
  update_parameters_for_new_input(); #possibly using heavy math
  generate_100_samples_as_fast_as_possible();
  push_samples_into_soundcard_buffer();
}

      [download]
      Hope this clarifies.
      Joost.
      "What should it profit a man, if he should win a flame war, yet lose his cool?"
[reply]
[d/l]
[select]
        this is basically excactly what i want.
        thanks!!

        apperently i overlooked the Audio::Play module while scanning through cpan...
        i am currently trying to install the Audio-1.029 module (which will hopefully work, since i had problems installing c-pan stuff fairly often...)
        is there any other way to get the Audio-1.029 module without having to do the makefile thing ? perfect would be all the files and some readme saying where to put them (i hope this question isn't too annoying...)
[reply]

In Section Seekers of Perl Wisdom