Greetings fellow monks.

I am writing a small little ditty that grabs an audio stream from one machine (using Audio Hijack Pro, if you're curious), pipes it over the network to a listening daemon which then plays said audio over a stereo. I'm working over an 802.11b network (higher latency than Ethernet).

My question arises from poor results I've been seeing. I can't figure out how to buffer a couple seconds of audio so that the bursty, lagged nature of the 802.11b transmission doesn't lead to buffer underruns in aplay. Right now I'm seeing an underrun every second or so. Nasty.

On the client side (sender), I've got a basic:

my $buf;
while ( read(STDIN, $buf, 128) ) {
    print SOCKET, $buf;
}

[download]

On the server side (receiver), I've currently got this:

# open up our pipe and turn off the default buffering
open AUDIO_OUT, "|/usr/bin/aplay -f S32_BE -r22050 -c2 --buffer-time=5
+00000 -" or die "aplay pipe broken\n";
select(AUDIO_OUT);
$| = 1;
select(STDOUT);

my $stream;
# these 2 lines are an attempt to fill up aplay's buffer
# it doesn't appear to work at all
read(CLIENT, $stream, 512);
print AUDIO_OUT $stream;

# read the stream and dump it out to aplay
while ( defined( $stream = <CLIENT> ) ) {
    print AUDIO_OUT $stream;
}

[download]

I've seen some disucssion here about sysread() vs. read(), but I can't seem to figure out how I would dump the audio to AUDIO_OUT without print() (you're not supposed to mix buffered functions with unbuffered ones).

Any help would be greatly appreciated! Chris H.

In reply to Audio Stream Buffer by reds

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