Source code for audiodiff

#! /usr/bin/env python

   This module contains functions for comparing audio files.

import chunk
import filecmp
import hashlib
import os
import subprocess

    import mutagenwrapper
except ImportError:
    mutagenwrapper = None

__version__ = '0.3.0'

#: Supported audio formats (extensions)
AUDIO_FORMATS = ['wav', 'flac', 'm4a', 'mp3']

#: Default FFmpeg path
FFMPEG_BIN = 'ffmpeg'

[docs]def equal(name1, name2, ffmpeg_bin=None): """Compares two files and returns ``True`` if they are considered equal. For audio files, they are equal if their uncompressed audio streams and tags (as reported by mutagenwrapper, except for ``encodedby`` which is ignored) are equal. For non-audio files, they must have the same content to be equal. """ if is_supported_format(name1) and is_supported_format(name2): return audio_equal(name1, name2, ffmpeg_bin) and tags_equal(name1, name2) else: return filecmp.cmp(name1, name2, False)
[docs]def audio_equal(name1, name2, ffmpeg_bin=None): """Compares two audio files and returns ``True`` if they have the same audio streams. """ return checksum(name1, ffmpeg_bin) == checksum(name2, ffmpeg_bin)
[docs]def tags_equal(name1, name2): """Compares two audio files and returns ``True`` if they have the same tags reported by mutagenwrapper. """ return tags(name1) == tags(name2)
[docs]def checksum(name, ffmpeg_bin=None): """Returns an SHA1 checksum of the uncompressed PCM (signed 24-bit little-endian) data stream of the audio file. Note that the checksums for the same file may differ across different platforms if the file format is lossy, due to floating point problems and different implementations of decoders. """ if ffmpeg_bin is None: ffmpeg_bin = ffmpeg_path() args = [ ffmpeg_bin, '-i', name, '-vn', '-f', 's24le', '-', ] # Check if the file is readable and raise an appropriate exception if not with open(name) as f: with open(os.devnull, 'wb') as fnull: proc = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE) sha1sum = _compute_sha1(proc.stdout) proc.wait() try: if sha1sum is None: raise ExternalLibraryError( return sha1sum finally: proc.stdout.close() proc.stderr.close()
def _compute_sha1(f): hasher = hashlib.sha1() empty = True while True: data = * 128) if not data: break empty = False hasher.update(data) if empty: return None return hasher.hexdigest()
[docs]def tags(name): """Returns tags in the audio file as a :class:`dict`. Its return value is the same as ``mutagenwrapper.read_tags``, except that single valued items (lists with length 1) are unwrapped and ``encodedby`` tag is removed. To read unmodified, but still normalized tags, use ``mutagenwrapper.read_tags``. For raw tags, use the ``mutagen`` library. """ if mutagenwrapper is None: raise ImportError('mutagenwrapper is required to read tags') if not is_supported_format(name): raise UnsupportedFileError(name + ' is not a supported audio file') if get_extension(name) == 'wav': return {} return dict((key, _unwrap(value)) for key, value in mutagenwrapper.read_tags(name).iteritems() if key != 'encodedby')
def _unwrap(x): n = len(x) if n == 0: return None elif n == 1: return x[0] else: return x
[docs]def get_extension(path): """ Returns the file extension of the specified path. Example:: >>> get_extension('a.pdf') 'pdf' >>> get_extension('') 'coffee' >>> get_extension('c') '' >>> get_extension('d/e.txt') 'txt' """ parts = os.path.basename(path).rsplit('.', 1) return parts[1] if len(parts) > 1 else ''
[docs]def is_supported_format(path): """Returns True if the specified path has an extension that is one of the supported formats. """ return get_extension(path) in AUDIO_FORMATS
[docs]def ffmpeg_path(): """Returns the path to FFmpeg binary.""" return os.environ.get('FFMPEG_BIN', FFMPEG_BIN)
[docs]class AudiodiffException(Exception): """The root class of all audiodiff-related exceptions."""
[docs]class UnsupportedFileError(AudiodiffException): """Raised when you pass a non-audio file to a function that expects audio files. """
[docs]class ExternalLibraryError(AudiodiffException): """Raised when there is an error during running FFmpeg."""