How about this command-line structure:

perl foo.pl --channel="1,forever" --channel="2,1:20" \
  --channel="3,2:50" --channel="7,forever"
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which is handled by this code:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
use Getopt::Long;
my @channels;
GetOptions('channel=s' => \@channels);
print Dumper(\@channels);
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You just have to parse the data out of @channels...