#!/usr/bin/env perl

use warnings;
use strict;

sub conv_stream
{
    my ($stream_ref) = @_;

    my $first = shift @$stream_ref;
    my $count = ( vec $first, 3, 2 ) || 1;
    # edit: I was using unpack and oct above

    # edit: No need to overwrite the "count" if first bits are 00 or 01
    if ( $count > 1 ) { ( vec $first, 3, 2 ) = 0; }

    my $next = join q{}, splice @$stream_ref, 0, ($count-1);
    my $pad  = (chr 0) x (4-$count);

    return unpack 'N', $pad . $first . $next;
}

# I'm not quite sure I have the right bit ordering...
my @stream = map { pack 'B8', $_ }
    ( '01010101', # 85
      '10101010', '10101010', # 10922
      '11001100', '11001100', '11001100' ); # 838860

print conv_stream( \@stream ), "\n" while ( @stream );