Sox (#48)

* update README to force python2
* add support for PRE_EMPHASIS detection; mark pre-emphasis as FLAGS PRE in .cue
* correct typo, s/ivar/type/ for pre_emphasis element in track table
* add SoxPeakTask, program/sox module, sox.peak_level()
* use sox peak detection in lieu of gstreamer

morituri/program/cdparanoia.py

@@ -492,6 +492,7 @@ class ReadVerifyTrackTask(log.Loggable, task.MultiSeparateTask):
             taglist=taglist, what=what))
         # make sure our encoding is accurate
         self.tasks.append(checksum.CRC32Task(tmpoutpath))
+        self.tasks.append(encode.SoxPeakTask(tmppath))
 
         self.checksum = None
 
@@ -502,7 +503,7 @@ class ReadVerifyTrackTask(log.Loggable, task.MultiSeparateTask):
             if not self.exception:
                 self.quality = max(self.tasks[0].quality,
                     self.tasks[2].quality)
-                self.peak = self.tasks[4].peak
+                self.peak = self.tasks[6].peak
                 self.debug('peak: %r', self.peak)
                 self.testspeed = self.tasks[0].speed
                 self.copyspeed = self.tasks[2].speed

morituri/program/sox.py

@@ -0,0 +1,16 @@
+import os
+import logging
+from subprocess import Popen, PIPE
+
+SOX = 'sox'
+
+def peak_level(track_path):
+	if not os.path.exists(track_path):
+		logging.warning("SoX peak detection failed: file not found")
+		return None
+	sox = Popen([SOX, track_path, "-n", "stat"], stderr=PIPE)
+	out, err = sox.communicate()
+	if sox.returncode:
+		logging.warning("SoX peak detection failed: " + s.returncode)
+		return None
+	return float(err.split('\n')[3].split()[2])	# Maximum amplitude: 0.123456