141 lines
4.4 KiB
Python
141 lines
4.4 KiB
Python
# -*- coding: utf-8 -*-
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from contextlib import contextmanager
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from media.monitor.pure import truncate_to_length, toposort
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import mutagen
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class MetadataAbsent(Exception):
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def __init__(self, name): self.name = name
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def __str__(self): return "Could not obtain element '%s'" % self.name
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class MetadataElement(object):
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def __init__(self,name):
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self.name = name
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# "Sane" defaults
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self.__deps = set()
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self.__normalizer = lambda x: x
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self.__optional = True
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self.__default = None
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self.__is_normalized = lambda _ : True
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self.__max_length = -1
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def max_length(self,l):
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self.__max_length = l
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def optional(self, setting):
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self.__optional = setting
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def is_optional(self):
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return self.__optional
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def depends(self, *deps):
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self.__deps = set(deps)
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def dependencies(self):
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return self.__deps
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def translate(self, f):
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self.__translator = f
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def is_normalized(self, f):
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self.__is_normalized = f
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def normalize(self, f):
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self.__normalizer = f
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def default(self,v):
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self.__default = v
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def get_default(self):
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if hasattr(self.__default, '__call__'): return self.__default()
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else: return self.__default
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def has_default(self):
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return self.__default is not None
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def path(self):
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return self.__path
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def __slice_deps(self, d):
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return dict( (k,v) for k,v in d.iteritems() if k in self.__deps)
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def __str__(self):
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return "%s(%s)" % (self.name, ' '.join(list(self.__deps)))
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def read_value(self, path, original, running={}):
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# If value is present and normalized then we don't touch it
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if self.name in original:
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v = original[self.name]
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if self.__is_normalized(v): return v
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else: return self.__normalizer(v)
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# A dictionary slice with all the dependencies and their values
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dep_slice_orig = self.__slice_deps(original)
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dep_slice_running = self.__slice_deps(running)
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full_deps = dict( dep_slice_orig.items()
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+ dep_slice_running.items() )
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# check if any dependencies are absent
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if len(full_deps) != len(self.__deps) or len(self.__deps) == 0:
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# If we have a default value then use that. Otherwise throw an
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# exception
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if self.has_default(): return self.get_default()
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else: raise MetadataAbsent(self.name)
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# We have all dependencies. Now for actual for parsing
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r = self.__normalizer( self.__translator(full_deps) )
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if self.__max_length != -1:
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r = truncate_to_length(r, self.__max_length)
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return r
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def normalize_mutagen(path):
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"""
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Consumes a path and reads the metadata using mutagen. normalizes some of
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the metadata that isn't read through the mutagen hash
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"""
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m = mutagen.File(path, easy=True)
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md = {}
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for k,v in m.iteritems():
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if type(v) is list: md[k] = v[0]
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else: md[k] = v
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# populate special metadata values
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md['length'] = getattr(m.info, u'length', 0.0)
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md['bitrate'] = getattr(m.info, 'bitrate', u'')
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md['sample_rate'] = getattr(m.info, 'sample_rate', 0)
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md['mime'] = m.mime[0] if len(m.mime) > 0 else u''
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md['path'] = path
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return md
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class MetadataReader(object):
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def __init__(self):
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self.clear()
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def register_metadata(self,m):
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self.__mdata_name_map[m.name] = m
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d = dict( (name,m.dependencies()) for name,m in
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self.__mdata_name_map.iteritems() )
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new_list = list( toposort(d) )
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self.__metadata = [ self.__mdata_name_map[name] for name in new_list
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if name in self.__mdata_name_map]
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def clear(self):
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self.__mdata_name_map = {}
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self.__metadata = []
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def read(self, path, muta_hash):
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normalized_metadata = {}
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for mdata in self.__metadata:
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try:
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normalized_metadata[mdata.name] = mdata.read_value(
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path, muta_hash, normalized_metadata)
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except MetadataAbsent:
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if not mdata.is_optional(): raise
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return normalized_metadata
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global_reader = MetadataReader()
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@contextmanager
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def metadata(name):
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t = MetadataElement(name)
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yield t
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global_reader.register_metadata(t)
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