code cleanup

-changed module name to correct naming convention
-remove some unused imports

python_apps/media-monitor/airtimefilemonitor/replaygain.py

@@ -0,0 +1,81 @@
+from subprocess import Popen, PIPE
+import re
+import os
+import sys
+
+def get_process_output(command):
+    """
+    Run subprocess and return stdout
+    """
+    p = Popen(command, shell=True, stdout=PIPE)
+    return p.communicate()[0].strip()
+
+def run_process(command):
+    """
+    Run subprocess and return "return code"
+    """
+    p = Popen(command, shell=True)
+    return os.waitpid(p.pid, 0)[1]
+
+def get_mime_type(file_path):
+    """
+    Attempts to get the mime type but will return prematurely if the process
+    takes longer than 5 seconds. Note that this function should only be called 
+    for files which do not have a mp3/ogg/flac extension.
+    """
+
+    return get_process_output("timeout 5 file -b --mime-type %s" % file_path)
+
+def calculate_replay_gain(file_path):
+    """
+    This function accepts files of type mp3/ogg/flac and returns a calculated ReplayGain value in dB.
+    If the value cannot be calculated for some reason, then we default to 0 (Unity Gain).
+    
+    TODO:
+    Currently some of the subprocesses called will actually insert metadata into the file itself,
+    which we do *not* want as this changes the file's hash. Need to make a copy of the file before
+    we run this function.
+    
+    http://wiki.hydrogenaudio.org/index.php?title=ReplayGain_1.0_specification
+    """
+
+    search = None
+    if re.search(r'mp3$', file_path, re.IGNORECASE) or get_mime_type(file_path) == "audio/mpeg":
+        if run_process("which mp3gain > /dev/null") == 0:
+            out = get_process_output('mp3gain -q "%s" 2> /dev/null' % file_path)
+            search = re.search(r'Recommended "Track" dB change: (.*)', out)
+        else:
+            print "mp3gain not found"
+            #Log warning
+    elif re.search(r'ogg$', file_path, re.IGNORECASE) or get_mime_type(file_path) == "application/ogg":
+        if run_process("which vorbisgain > /dev/null  && which ogginfo > /dev/null") == 0:
+            run_process('vorbisgain -q -f "%s" 2>/dev/null >/dev/null' % file_path)
+            out = get_process_output('ogginfo "%s"' % file_path)
+            search = re.search(r'REPLAYGAIN_TRACK_GAIN=(.*) dB', out)
+        else:
+            print "vorbisgain/ogginfo not found"
+            #Log warning
+    elif re.search(r'flac$', file_path, re.IGNORECASE) or get_mime_type(file_path) == "audio/x-flac":
+        if run_process("which metaflac > /dev/null") == 0:
+            out = get_process_output('metaflac --show-tag=REPLAYGAIN_TRACK_GAIN "%s"' % file_path)
+            search = re.search(r'REPLAYGAIN_TRACK_GAIN=(.*) dB', out)
+        else:
+            print "metaflac not found"
+            #Log warning
+    else:
+        pass
+        #Log unknown file type.
+
+    replay_gain = 0
+    if search:
+        matches = search.groups()
+        if len(matches) == 1:
+            replay_gain = matches[0]
+
+    return replay_gain
+
+
+# Example of running from command line:
+# python replay_gain.py /path/to/filename.mp3
+if __name__ == "__main__":
+    print calculate_replay_gain(sys.argv[1])