#!/usr/bin/perl

###
### Print the duration of an audio file in useful formats,
### including partial cdda frames (1/75 sec).
### Uses sndfile-info(1) to examine the audio file, so many
### sound formats are supported.
###

use Getopt::Std;

$sph    = 60 * 60;
$cdrate = 44100;   # scans per second
$cdfps  = 75;      # cdda frames per second
$cdscpf = $cdrate / $cdfps;  # scans per frame: 44100/75 = 588
$head_printed = 0;

@ARGV or die "No file or #samples specified";

getopts('v');

if (@ARGV[0] =~ /^\d+$/ and ! -f $ARGV[0]) {
    $scans = $ARGV[0];
    die "Bad scans value: $scans" unless $scans > 0;
    shift(@ARGV);
}
if (@ARGV and @ARGV[0] =~ /^\d+$/ and ! -f $ARGV[0]) {
    $rate = $ARGV[0];
    die "Bad data rate value: $rate" unless $rate > 0;
    shift(@ARGV);
}

$rate ||= $cdrate;

foreach my $arg (@ARGV) {

    my $quarg;

    $arg =~ s/%=20/ /g; # unquote spaces

    unless ( -f $arg and -r $arg) {
	warn "file '$arg' doesn't exist or not readable";
	next;
    }
    # quote funny chars in filename to protect from shell
    ($quarg = $arg) =~ s/([\W])/\\$1/g;

    open INFO, "sndfile-info $quarg|" or
	die "can't open file '$arg': $@";

    while (<INFO>) {
	if (/sample\s+rate/i) {
	    $rate = (split(/\s*\:\s*/))[1] || die "bad sample rate";
	    next;
	}
	if (/frames/i) {
	    $scans = (split(/\s*\:\s*/))[1] || die "bad scan count";
	    next;
	}
	if (/channels/i) {
	    $channels = (split(/\s*\:\s*/))[1] || die "bad channel count";
	    next;
	}
	if (/signal\s+max/i) {
	    $max = (split(/\s*\:\s*/))[1] || die "bad sample rate";
	    next;
	}
	if (/format not recognised/i) {
	    die "can't handle this type of sound file";
	}
    }

    unless ($rate and $scans) {
	warn "can't extract needed info from file '$arg'";
	next;
    }

    {
	use integer;

	# total whole seconds
	$isec = $scans / $rate;

	$h = $isec / $sph;

	# seconds, minutes beyond $h hours
	$isec %= $sph;
	$m    =  $isec / 60;

	# whole seconds beyond $m minutes
	$s = $isec %= 60;

	# milliseconds (ms) beyond $isec (scale #'s for int calc)
	$ms = (($scans * 10)/($rate/100)) % 1000;

	# whole cdda frames past whole second
	$cdf = ($scans % $rate) / $cdscpf;

	# partial cdda frames (0-587 samples)
	$xcdf = $scans % $cdscpf;
    }

    # seconds, 'n.m
    $fsec = sprintf("%.3f", $scans/$rate);
    # hh:mm:ss.sss
    $fhms = sprintf("%02d:%02d.%03d", ($h*60 + $m), $s, $ms);
    # cd audio mm:ss:cdf.fff
    $fcdf = $rate == $cdrate ?
	sprintf("%02d:%02d:%03d+%03d",
		($h*60 + $m), $s, $cdf, $xcdf, $cdfps) :
		sprintf("%02d:%02d:---+---",
			($h*60 + $m), $s, $cdf, $xcdf, $cdfps);
    print join("\t", 'seconds', 'hh:mm:s.s', 'mm:ss:cdf+s', 'file'), "\n"
	unless $head_printed++;
    print join("\t", $fsec, $fhms, $fcdf, $arg), "\n";

    if ($opt_v) {

	print "[$arg]\n";

	printf "%g seconds\n", $scans/$rate;

	printf "%02d:%02d.%03d  (m:s.ms)\n", ($h*60 + $m), $s, $ms;

	if ($rate == $cdrate) {
	    printf "%02d:%02d:%03d+%03d  (m:s:frames+samples @%gfps)\n",
	    ($h*60 + $m), $s, $cdf, $xcdf, $cdfps;

	    printf "%d+%03d  (frames+samples @%gfps)\n",
	    int ($scans/$cdscpf),$scans % $cdscpf, $cdfps;
	}
	# max audio level 0-32768 n.m dB
	printf "%s\n", $max;
    }
}