re-add replay gain to old media-monitor

python_apps/media-monitor/airtimefilemonitor/replaygain.py

@@ -0,0 +1,107 @@
+from subprocess import Popen, PIPE
+import re
+import os
+import sys
+import shutil
+import tempfile
+
+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 duplicate_file(file_path):
+    """
+    Makes a duplicate of the file and returns the path of this duplicate file.
+    """
+    fsrc = open(file_path, 'r')
+    fdst = tempfile.NamedTemporaryFile(delete=False)
+
+    print "Copying %s to %s" % (file_path, fdst.name)
+
+    shutil.copyfileobj(fsrc, fdst)
+
+    fsrc.close()
+    fdst.close()
+
+    return fdst.name
+
+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).
+       
+    http://wiki.hydrogenaudio.org/index.php?title=ReplayGain_1.0_specification
+    """
+
+    try:
+        """
+        Making a duplicate is required because the ReplayGain extraction utilities we use
+        make unwanted modifications to the file. 
+        """
+
+        search = None
+        temp_file_path = duplicate_file(file_path)
+
+        if re.search(r'mp3$', temp_file_path, re.IGNORECASE) or get_mime_type(temp_file_path) == "audio/mpeg":
+            if run_process("which mp3gain > /dev/null") == 0:
+                out = get_process_output('mp3gain -q "%s" 2> /dev/null' % temp_file_path)
+                search = re.search(r'Recommended "Track" dB change: (.*)', out)
+            else:
+                print "mp3gain not found"
+                #Log warning
+        elif re.search(r'ogg$', temp_file_path, re.IGNORECASE) or get_mime_type(temp_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' % temp_file_path)
+                out = get_process_output('ogginfo "%s"' % temp_file_path)
+                search = re.search(r'REPLAYGAIN_TRACK_GAIN=(.*) dB', out)
+            else:
+                print "vorbisgain/ogginfo not found"
+                #Log warning
+        elif re.search(r'flac$', temp_file_path, re.IGNORECASE) or get_mime_type(temp_file_path) == "audio/x-flac":
+            if run_process("which metaflac > /dev/null") == 0:
+                out = get_process_output('metaflac --show-tag=REPLAYGAIN_TRACK_GAIN "%s"' % temp_file_path)
+                search = re.search(r'REPLAYGAIN_TRACK_GAIN=(.*) dB', out)
+            else:
+                print "metaflac not found"
+                #Log warning
+        else:
+            pass
+            #Log unknown file type.
+
+        #no longer need the temp, file simply remove it.
+        os.remove(temp_file_path)
+    except Exception, e:
+        print e
+
+    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])