Re: MIDI::Realtime and sblive with linux

On Sat, 19 Jun 2004 11:27:33 -0400, [email protected] (Zentara)
wrote:

>I'm using kernel 2.4.22 and Alsa 1.0.4., and Perl 5.8.3
>
>So the soundcard.h problem dosn't appear anymore,
>but when I try to run the module's example code, I get
>the error:
>"Couldn't write to /dev/sequencer, bad file descriptor
>at (....)Realtime.pm line 201.

Well I did somemore digging into this, and got some results.
I put a die  on the sysopen in the Realtime.pm and found out that
/dev/sequencer dosn't exist in ALSA.  So I looked at how alsa's
midiplayer runs with strace, and it seems to write to /dev/snd/seq.

I tried to replace /dev/sequencer with /dev/amidi  and the sample
script runs without error, but there is no sound output from the
soundcard. However, I have a nearby FM radio which plays increased
"static" for the duration of the script.....so I'm guessing that the
script is writing to /dev/amidi.

Digging further, it seems likely that the alsa programming interface,
dosn't like the &SEQ_MIDIPUTC() map (which is from soundcard.ph).

So I will dig somemore, to see how to use that soundcard.ph function.


>Line 201 is in this sub:
>###############################################
>sub send_midi_bytes { 
>  my $self = shift; 
>   
>  my $device = $self->midi_device; 
> 
>  my $stuff = pack('C*',  
>                   (map {&SEQ_MIDIPUTC(), 
>                         $_,  
>                         $device, 
>                         0 
>                        } 
>                    @_ 
>                   ) 
>                  ); 
> 
>  my $bytes = syswrite(SEQ_FH, $stuff); 
> 
>  if (not $bytes) { 
>    die("Couldn't write to " 
>        . $self->dev  
>        . ": $!" 
>       ); 
>  } 
> 
>  return $bytes; 
>} 
>#########################################################
>
>The code I'm trying to run is:
>
>#!/usr/bin/perl
>use warnings;
>use strict;
>use MIDI::Realtime;
>
>my $midi = MIDI::Realtime->new();
>
># Play note 47 with maximum velocity on channel 1 
>$midi->note(47, 127, 1);
>
># Now have some fun with randomness 
>
>my @notes      = (37 .. 50);
># use all the channels (with extra drums) 
>my @channels   = (1 .. 16, 10, 10, 10);
>my @velocities = (70 .. 100);
>
>for (0 .. 127) {
>$midi->note($notes[rand(@notes)],
>$channels[rand(@channels)],
>$velocities[rand(@velocities)]
>);
>
># Wait for a tenth of a second 
>select(undef,undef,undef, 0.10);
>}
>__END__
>############################################
>
>
>So I'll dig somemore, but if anyone knows how to setup
>the right file descriptor, please edify us. :-)

-- 
I'm not really a human, but I play one on earth.
http://zentara.net/japh.html