From 122f3c401f23f84799802c7b9667bda222646487 Mon Sep 17 00:00:00 2001
From: "B. Watson" <yalhcru@gmail.com>
Date: Wed, 8 Apr 2015 03:18:53 -0400
Subject: initial commit

---
 calc_bitrate.pl | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100755 calc_bitrate.pl

(limited to 'calc_bitrate.pl')

diff --git a/calc_bitrate.pl b/calc_bitrate.pl
new file mode 100755
index 0000000..1acc829
--- /dev/null
+++ b/calc_bitrate.pl
@@ -0,0 +1,84 @@
+#!/usr/bin/perl -w
+
+$|++;
+
+$def{tracklen} = 0;
+$def{filesize} = 700;
+$def{audiorate} = 192;
+
+open(D, "<$ENV{HOME}/.calc_bitrate") && do {
+	while(<D>) {
+		chomp;
+		s/#.*//;
+		my ($k, $v) = split;
+		$v ||= "";
+		$def{$k} = $v if $k;
+	}
+	close D;
+};
+
+print "Length of input (seconds or hh:mm:ss, \"d\" to scan DVD) [$def{tracklen}]: ";
+chomp ($length = <>);
+
+$length = $def{tracklen} if $length eq "";
+
+if($length =~ /^[\d:]+$/) {
+	if($length =~ /(?:(\d?\d):)?(\d\d):(\d\d)/) {
+		my $newlength = $3 + 60 * $2 + 3600 * $1;
+		print "$length == $newlength seconds\n";
+		$length = $newlength;
+	}
+} elsif($length =~ /^d/i) {
+	open L, "lsdvd|" or die "Can't find lsdvd in PATH\n";
+	while(<L>) {
+		chomp;
+		next unless $_;
+		print $_, "\n";
+#Title: 01, Length: 02:56:48.066 Chapters: 19, Cells: 20, Audio streams: 01, Subpictures: 03
+		if(/^Title:\s*(\d+),\s*Length:\s*(\d?\d):(\d\d):(\d\d)(?:\.\d+)?\s*Chapters:\s*(\d+)/)
+		{
+			my $track = $1;
+			my $len = $4 + 60 * $3 + 3600 * $2;
+			my $chaps = $5;
+			$tracklens{$track+0} = $len;
+#			$trackchaps{$track+0} = $chaps;
+		}
+		$dtrack = $1 if /^Longest track: (\d+)/;
+	}
+
+	print "Select track [$dtrack]: ";
+	chomp ($track = <>);
+	$track = $dtrack unless $track;
+	$track += 0;
+	$length = $tracklens{$track};
+} else {
+	die "Invalid length\n";
+}
+
+print "Desired AVI size in megabytes [$def{filesize}]: ";
+chomp ($s = <>);
+$size = $s ? $s : $def{filesize};
+
+print "Audio bitrate [$def{audiorate}]: ";
+chomp ($b = <>);
+$abit = $b ? $b : $def{audiorate};
+
+open(D, ">$ENV{HOME}/.calc_bitrate") && do {
+	print D "audiorate $abit\n" if $abit;
+	print D "tracklen $length\n" if $length;
+	print D "filesize $size\n" if $size;
+};
+
+close D;
+
+# calculate total bitrate:
+$totalbits = $size * 1024 * 1024 * 8;
+$bits_sec = $totalbits / $length;
+$kbits_sec = $bits_sec / 1000;
+$vbit = $kbits_sec - $abit;
+
+# fudge factor:
+#$vbit *= 0.985;
+$vbit *= 0.992;
+
+print "Video bitrate for $length seconds \@ $size MB: $vbit\n";
-- 
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