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/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