From 3e09ac0c10c95bb24a08af62393b4f761e2743d0 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Sat, 24 Aug 2013 09:54:45 +0000
Subject: initial commit

---
 lib/dtas/source/mp3.rb | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 lib/dtas/source/mp3.rb

(limited to 'lib/dtas/source/mp3.rb')

diff --git a/lib/dtas/source/mp3.rb b/lib/dtas/source/mp3.rb
new file mode 100644
index 0000000..b013bee
--- /dev/null
+++ b/lib/dtas/source/mp3.rb
@@ -0,0 +1,38 @@
+# -*- encoding: binary -*-
+# :stopdoc:
+# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net>
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+require_relative '../process'
+
+module DTAS::Source::Mp3
+  include DTAS::Process
+  # we use dBFS = 1.0 as scale (not 32768)
+  def __mp3gain_peak(str)
+    sprintf("%0.8g", str.to_f / 32768.0)
+  end
+
+  # massage mp3gain(1) output
+  def mp3gain_comments
+    tmp = {}
+    case @infile
+    when String
+      @infile =~ /\.mp[g23]\z/i or return
+      qx(%W(mp3gain -s c #@infile)).split(/\n/).each do |line|
+        case line
+        when /^Recommended "(Track|Album)" dB change:\s*(\S+)/
+          tmp["REPLAYGAIN_#{$1.upcase}_GAIN"] = $2
+        when /^Max PCM sample at current gain: (\S+)/
+          tmp["REPLAYGAIN_TRACK_PEAK"] = __mp3gain_peak($1)
+        when /^Max Album PCM sample at current gain: (\S+)/
+          tmp["REPLAYGAIN_ALBUM_PEAK"] = __mp3gain_peak($1)
+        end
+      end
+      tmp
+    else
+      raise TypeError, "unsupported type: #{@infile.inspect}"
+    end
+  rescue => e
+    $DEBUG and
+        warn("mp3gain(#{@infile.inspect}) failed: #{e.message} (#{e.class})")
+  end
+end
-- 
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