Martin Krzywinski - The Perl Journal - Canada's Michael Smith Genome Sciences Centre

I reformatted the CD-ROM contents. Some things may still be a little wonky — oh, why hello there <FONT> tag. Syntax highlighting is iffy. Please report any glaring issues.

listing 1

An IP Telephone in 74 Lines of PERL The Perl Journal, Fall 2000

Lincoln D. Stein (2000) An IP Telephone in 74 Lines of Perl. The Perl Journal, vol 5(3), issue #19, Fall 2000.

Make a new outgoing connection.

 0    #!/usr/bin/perl
 1    use strict;
 2    use IO::File;
 3    use IO::Socket;
 4    use constant BUFSIZE => 4000;
 5    use constant DSP     => '/dev/dsp';
 6    $SIG{CHLD} = sub { exit 0 };
 7    my $dest = shift || 'prego';
 8    my $port = shift || 2007;
 9    my $sock = IO::Socket::INET->new("$dest:$port") || die "Can't connect: $!";
 10   warn "Connected, go ahead...\n";
 11   my $dsp = IO::File->new(DSP, "r+") || die "Can't open DSP: $!";
 12   my $child = fork();
 13   die "Can't fork: $!" unless defined $child;
 14   my $data;
 15   if ($child) { # parent process
 16       print $dsp $data while sysread($sock, $data, BUFSIZE);
 17       kill TERM => $child;
 18   } else {
 19       print $sock $data while sysread($dsp, $data, BUFSIZE);
 20   }

listing 2

An IP Telephone in 74 Lines of PERL The Perl Journal, Fall 2000

Lincoln D. Stein (2000) An IP Telephone in 74 Lines of Perl. The Perl Journal, vol 5(3), issue #19, Fall 2000.

Accept incoming connections.

 0    #!/usr/bin/perl
 1    use strict;
 2    use IO::Socket;
 3    use IO::File;
 4    use constant DSP     => '/dev/dsp';
 5    use constant BUFSIZE => 4000;
 6    $SIG{CHLD} = sub { wait };
 7    my $port = shift || 2007;
 8    my $listen = IO::Socket::INET->new(LocalPort => $port,
 9                                       Listen => 5,
 10                                       Reuse => 1) 
                     || die "Can't listen: $!";
 11   while (1) {
 12       warn "waiting for a connection...\n";
 13       my $sock = $listen->accept;
 14       warn "accepting connection from ", $sock->peerhost, "\n";
 15       unless (my $dsp = IO::File->new(DSP, "r+")) {
 17           close $sock;
 18       } else {
 19           handle_connection($sock, $dsp);
 20       }
 21   }
 22   sub handle_connection {
 23       my ($sock, $dsp) = @_;
 24       my $child = fork();
 25       die "Can't fork: $!" unless defined $child;
 26       my $data;
 27       if ($child) { # parent process
 28           eval {
 29             local $SIG{INT} = sub {die};
 30             print $dsp $data while sysread($sock, $data, BUFSIZE);
 31           };
 32           close $sock;
 33           kill TERM => $child;
 34       } else {
 35           close $listen;
 36           print $sock $data while sysread($dsp, $data, BUFSIZE);
 37           exit;
 38       }
 39   }

listing 3

An IP Telephone in 74 Lines of PERL The Perl Journal, Fall 2000

Lincoln D. Stein (2000) An IP Telephone in 74 Lines of Perl. The Perl Journal, vol 5(3), issue #19, Fall 2000.

The `DSP.pm` module, which reads and writes MP3 data.

 0    package DSP;
 1    use strict;
 2    use IO::File;
 3    use Carp 'croak';
 4    use vars '%sizeof', '@ISA';
 5    @ISA = 'IO::Handle';
 6    BEGIN {
 7      use Config;
 8      %sizeof= ( int => $Config{intsize} );
 9      require "sys/soundcard.ph";
 10   }
 11   use constant DSP        => '/dev/dsp';
 12   use constant COMPRESS   => $Config{byteorder} eq '1234'
 13                              ? "lame -r -x -m m -b32 -s16 - - |"
 14                              : "lame -r    -m m -b32 -s16 - - |";
 15   use constant UNCOMPRESS => "| mpg123 -s -m -";
 16   sub new {
 17       my $class = shift;
 18       my $dsp = IO::File->new('/dev/dsp', 'r+') 
                      or croak "Can't open /dev/dsp: $!";
 19       croak "can't set samplesize: $!" 
            unless ioctl $dsp, SNDCTL_DSP_SAMPLESIZE, pack("I", 16);
 20       croak "can't set speed: $!"      
            unless ioctl $dsp, SNDCTL_DSP_SPEED, pack("I", 16000);
 21       croak "can't set mono: $!"       
            unless ioctl $dsp, SNDCTL_DSP_STEREO, pack("I", 0);
 22       return bless $dsp, $class;
 23   }
 24   # read from encode to get MP3 from microphone
 25   sub compress {
 26       my $self = shift;
 27       open(S, "<&STDIN");
 28       STDIN->fdopen($self, "r") or die "Can't reopen STDIN on DSP: $!";
 29       my $encode = IO::File->new(COMPRESS) or croak "Can't open lame: $!";
 30       open(STDIN, "<&S");
 31       return $encode;
 32   }
 33   # write to decode to get sound from MP3
 34   sub uncompress {
 35       my $self = shift;
 36       open(S, ">&STDOUT");
 37       STDOUT->fdopen($self, "w") or die "Can't reopen STDOUT on DSP: $!";
 38       my $uncompress = IO::File->new(UNCOMPRESS) 
            or die "Can't open mpg123: $!";
 39       $uncompress->autoflush(1);
 40       open(STDOUT, ">&S");
 41       return $uncompress;
 42   }
 43   1;

listing 4

An IP Telephone in 74 Lines of PERL The Perl Journal, Fall 2000

Lincoln D. Stein (2000) An IP Telephone in 74 Lines of Perl. The Perl Journal, vol 5(3), issue #19, Fall 2000.

`mp3_send.pl` initiates MP3-encoded telephone calls.

 0    #!/usr/bin/perl
 1    # file mp3_send.pl
 2    use strict;
 3    use DSP;
 4    use IO::Socket;
 5    use constant BUFSIZE => 1024;
 6    $SIG{CHLD} = sub { exit 0 };
 7    my $dest = shift || 'prego';
 8    my $port = shift || 2007;
 9    my $sock = IO::Socket::INET->new("$dest:$port") 
        || die "Can't connect: $!";
 10   my $dsp = new DSP;
 11   my $child = fork();
 12   die "Can't fork: $!" unless defined $child;
 13   my $data;
 14   if ($child) { # parent process
 15       my $uncompress = $dsp->uncompress;
 16       print $uncompress $data while sysread($sock, $data, BUFSIZE);
 17       kill TERM => $child;
 18   } else {
 19       my $compress = $dsp->compress;
 20       print $sock $data while sysread($compress, $data, BUFSIZE);
 21   }

listing 5

An IP Telephone in 74 Lines of PERL The Perl Journal, Fall 2000

Lincoln D. Stein (2000) An IP Telephone in 74 Lines of Perl. The Perl Journal, vol 5(3), issue #19, Fall 2000.

`mp3_recv.pl` accepts MP3-encoded telephone calls.

 0    #!/usr/bin/perl
 1    # file: mp3_recv.pl
 2    use strict;
 3    use DSP;
 4    use IO::Socket;
 5    use constant BUFSIZE => 1024;
 6    $SIG{CHLD} = sub { wait; };
 7    my $dest = shift || 'prego';
 8    my $port = shift || 2007;
 9    my $listen = IO::Socket::INET->new(LocalPort => $port,
 10                                      Listen => 5,
 11                                       Reuse => 1) || die "Can't listen: $!";
 12   while (1) {
 13       warn "waiting for a connection...\n";
 14       my $sock = $listen->accept;
 15       warn "accepting connection from ", $sock->peerhost,"\n";
 16       unless (my $dsp = new DSP) {
 17           warn "DSP unavailable.  Hanging up.\n";
 18           close $sock;
 19       } else {
 20           handle_connection($sock, $dsp);
 21       }
 22   }
 23   sub handle_connection {
 24       my ($sock, $dsp) = @_;
 25       my $child = fork();
 26       die "Can't fork: $!" unless defined $child;
 27       my $data;
 28       if ($child) { # parent process
 29           eval {
 30             local $SIG{INT} = sub {die};
 31             my $uncompress = $dsp->uncompress;
 32             print $uncompress $data while sysread($sock, $data, BUFSIZE);
 33           };
 34           close $sock;
 35           kill TERM => $child;
 36       } else {
 37           close $listen;
 38           my $compress = $dsp->compress;
 39           print $sock $data while sysread($compress, $data, BUFSIZE);
 40           exit;
 41       }
 42   }

The Perl Journal

Volumes 1–6 (1996–2002)

An IP Telephone in 74 Lines of Perl

Lincoln D. Stein

The Simple Version

Adding an MP3 Encoder

Summary

listing 1

Make a new outgoing connection.

listing 2

Accept incoming connections.

listing 3

The `DSP.pm` module, which reads and writes MP3 data.

listing 4

`mp3_send.pl` initiates MP3-encoded telephone calls.

listing 5

`mp3_recv.pl` accepts MP3-encoded telephone calls.

The Perl Journal

Volumes 1–6 (1996–2002)

An IP Telephone in 74 Lines of Perl

Lincoln D. Stein

The Simple Version

Adding an MP3 Encoder

Summary

listing 1

Make a new outgoing connection.

listing 2

Accept incoming connections.

listing 3

The DSP.pm module, which reads and writes MP3 data.

listing 4

mp3_send.pl initiates MP3-encoded telephone calls.

listing 5

mp3_recv.pl accepts MP3-encoded telephone calls.

The `DSP.pm` module, which reads and writes MP3 data.

`mp3_send.pl` initiates MP3-encoded telephone calls.

`mp3_recv.pl` accepts MP3-encoded telephone calls.