from subprocess import Popen, PIPE import re import os import sys import shutil import tempfile import logging logger = logging.getLogger() def get_process_output(command): """ Run subprocess and return stdout """ #logger.debug(command) 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) #logger.info("Copying %s to %s" % (file_path, fdst.name)) shutil.copyfileobj(fsrc, fdst) fsrc.close() fdst.close() return fdst.name def get_file_type(file_path): file_type = None if re.search(r'mp3$', file_path, re.IGNORECASE): file_type = 'mp3' elif re.search(r'og(g|a)$', file_path, re.IGNORECASE): file_type = 'vorbis' elif re.search(r'flac$', file_path, re.IGNORECASE): file_type = 'flac' else: mime_type = get_mime_type(file_path) == "audio/mpeg" if 'mpeg' in mime_type: file_type = 'mp3' elif 'ogg' in mime_type: file_type = 'vorbis' elif 'flac' in mime_type: file_type = 'flac' return file_type 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) file_type = get_file_type(file_path) if file_type: if file_type == 'mp3': 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: logger.warn("mp3gain not found") elif file_type == 'vorbis': 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: logger.warn("vorbisgain/ogginfo not found") elif file_type == '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: logger.warn("metaflac not found") else: pass #no longer need the temp, file simply remove it. os.remove(temp_file_path) except Exception, e: logger.error(str(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])