fix for mpeg based wavs

lib/nu_wav.rb

@@ -178,8 +178,7 @@ def self.from_mpeg(file_name)
       wave = WaveFile.new
 
       # data chunk
-      data = DataChunk.new
-      data.data = file.read
+      data = DataChunk.new_from_file(file)
       wave.chunks[:data] = data
 
       # fmt chunk
@@ -599,6 +598,14 @@ def self.parse(id, size, file)
 
       return chunk
     end
+
+    def self.new_from_file(file)
+      tmp_data = Tempfile.open('data_chunk')
+      tmp_data.binmode
+      File.copy(file.path, tmp_data.path)
+      tmp_data.rewind
+      self.new('data', File.size(file.path), tmp_data)
+    end
 
     def initialize(id=nil, size=nil, tmp_data_file=nil)
       @id, @size, @tmp_data_file = id, size, tmp_data_file

test/test_nu_wav.rb

@@ -1,6 +1,7 @@
 require 'helper'
 require 'nu_wav'
 require 'tempfile'
+require 'ftools'
 
 class TestNuWav < Test::Unit::TestCase
   include NuWav
@@ -85,6 +86,12 @@ def test_parse_wav_with_bwf_and_cart_chunk
     puts "end of test: #{memory_usage/1024} mb"
   end
 
+  def test_from_mpeg
+    w = WaveFile.from_mpeg(File.expand_path(File.dirname(__FILE__) + '/files/test.mp2'))
+    w.to_file('test_from_mpeg.wav')
+    w.write_data_file('test_from_mpeg.mp2')
+  end
+
   def unpad(str)
     str.gsub(/\0*$/, '')
   end