/Lib/plat-mac/Carbon/MediaDescr.py
http://unladen-swallow.googlecode.com/ · Python · 97 lines · 81 code · 13 blank · 3 comment · 8 complexity · 8934ed5aec262aef615fb0bb94fc9fea MD5 · raw file
- # Parsers/generators for QuickTime media descriptions
- import struct
- Error = 'MediaDescr.Error'
- class _MediaDescriptionCodec:
- def __init__(self, trunc, size, names, fmt):
- self.trunc = trunc
- self.size = size
- self.names = names
- self.fmt = fmt
- def decode(self, data):
- if self.trunc:
- data = data[:self.size]
- values = struct.unpack(self.fmt, data)
- if len(values) != len(self.names):
- raise Error, ('Format length does not match number of names', descr)
- rv = {}
- for i in range(len(values)):
- name = self.names[i]
- value = values[i]
- if type(name) == type(()):
- name, cod, dec = name
- value = dec(value)
- rv[name] = value
- return rv
- def encode(dict):
- list = [self.fmt]
- for name in self.names:
- if type(name) == type(()):
- name, cod, dec = name
- else:
- cod = dec = None
- value = dict[name]
- if cod:
- value = cod(value)
- list.append(value)
- rv = struct.pack(*list)
- return rv
- # Helper functions
- def _tofixed(float):
- hi = int(float)
- lo = int(float*0x10000) & 0xffff
- return (hi<<16)|lo
- def _fromfixed(fixed):
- hi = (fixed >> 16) & 0xffff
- lo = (fixed & 0xffff)
- return hi + (lo / float(0x10000))
- def _tostr31(str):
- return chr(len(str)) + str + '\0'*(31-len(str))
- def _fromstr31(str31):
- return str31[1:1+ord(str31[0])]
- SampleDescription = _MediaDescriptionCodec(
- 1, # May be longer, truncate
- 16, # size
- ('descSize', 'dataFormat', 'resvd1', 'resvd2', 'dataRefIndex'), # Attributes
- "l4slhh" # Format
- )
- SoundDescription = _MediaDescriptionCodec(
- 1,
- 36,
- ('descSize', 'dataFormat', 'resvd1', 'resvd2', 'dataRefIndex',
- 'version', 'revlevel', 'vendor', 'numChannels', 'sampleSize',
- 'compressionID', 'packetSize', ('sampleRate', _tofixed, _fromfixed)),
- "l4slhhhh4shhhhl" # Format
- )
- SoundDescriptionV1 = _MediaDescriptionCodec(
- 1,
- 52,
- ('descSize', 'dataFormat', 'resvd1', 'resvd2', 'dataRefIndex',
- 'version', 'revlevel', 'vendor', 'numChannels', 'sampleSize',
- 'compressionID', 'packetSize', ('sampleRate', _tofixed, _fromfixed), 'samplesPerPacket',
- 'bytesPerPacket', 'bytesPerFrame', 'bytesPerSample'),
- "l4slhhhh4shhhhlllll" # Format
- )
- ImageDescription = _MediaDescriptionCodec(
- 1, # May be longer, truncate
- 86, # size
- ('idSize', 'cType', 'resvd1', 'resvd2', 'dataRefIndex', 'version',
- 'revisionLevel', 'vendor', 'temporalQuality', 'spatialQuality',
- 'width', 'height', ('hRes', _tofixed, _fromfixed), ('vRes', _tofixed, _fromfixed),
- 'dataSize', 'frameCount', ('name', _tostr31, _fromstr31),
- 'depth', 'clutID'),
- 'l4slhhhh4sllhhlllh32shh',
- )
- # XXXX Others, like TextDescription and such, remain to be done.