[LAD] forward: jack session api in perl, python, ruby, and lua

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To: <linux-audio-dev@...>
Cc: Ed Sweeney <ed@...>
Date: Sunday, March 18, 2012 - 11:40 pm

I am forwarding a mail and sample code from Ed Sweeney
(with permission).

He'd appreciate any comments.

---------------------------------------------------------------------
Joel,

Programming jack is fun.

Check out the attached, it is jack's simple_session_client.c in perl.

I don't know how to test the savequit session events but support for
them is coded and the sample processing totally works. I rewrote
metro.c metronome in perl too, works.

I have generated API libs for perl, python, ruby, and lua. Each of
them has a reworked simple_client that works. Ruby has a bug with the
metronome I haven't been able to find yet.

I'm sure there are lots of bugs and wrong design choices and poorly
chosen names but it is a start!

The build system is messy. I'll put a tarball on a server and tar up
a binary installable perl module today. If this looks like it will be
usable, I'll put it on github.

-- simple_client.pl --

#!/usr/bin/perl
use jackscript;
use strict;
use warnings;
use Cwd 'abs_path';

my $jc;

if (defined($ARGV[0])) {
print("restarting with uuid $ARGV[0]\n");
$jc = jackscript::JsClient->new("simpler", $ARGV[0], $jackscript::JackSessionID);
} else {
$jc = jackscript::JsClient->new("simpler", undef, $jackscript::JackNullOption);
}

my $in = $jc->registerPort("input", $jackscript::JackPortIsInput);

my $out = $jc->registerPort("output", $jackscript::JackPortIsOutput);

$jc->activate();

my $done = undef;
until($done) {

my $jsevent = $jc->getEvent(-1);

if ($jsevent->getType() == $jackscript::PROCESS) {

my $inbuffer = $in->getBuffer();

my $outbuffer = $out->getBuffer();

my $nframes = $outbuffer->length();

for (my $i = 0; $i < $nframes; $i++) { #copy input to putput

my $s = $inbuffer->getf($i);

$outbuffer->setf($i,$s);

}

} elsif ($jsevent->getType() == $jackscript::SAMPLE_RATE_CHANGE) {

my $sr = $jc->getSampleRate();
print("sample rate change event: sample rate is now $sr\n");

} elsif ($jsevent->getType() == $jackscript::SHUTDOWN) {

print("jack shutdown event\n");
$done = "done!";

} elsif ($jsevent->getType() == $jackscript::SESSION) {

my $dir = $jsevent->getSessionDir();
my $uuid = $jsevent->getUuid();
my $se_type = $jsevent->getSessionEventType();
my $setypeTxt = $se_type == $jackscript::JackSessionSave ? "save" : "quit";

print("session notification: path $dir, uuid $uuid, type: $setypeTxt\n");

if ($se_type == $jackscript::JackSessionSaveAndQuit) {
$done = "done!";
}

my $script_path = abs_path($0);
my $cmd = "perl $script_path $uuid";
$jsevent->setCommandLine($cmd); #tell jackd how to restart us

} else {
die("unknown event type\n");
}

$jsevent->complete();
}

print("simple_client.pl ended\n");

--
Joel Roth

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