| 1 | # Parsers/generators for QuickTime media descriptions
|
|---|
| 2 | import struct
|
|---|
| 3 |
|
|---|
| 4 | Error = 'MediaDescr.Error'
|
|---|
| 5 |
|
|---|
| 6 | class _MediaDescriptionCodec:
|
|---|
| 7 | def __init__(self, trunc, size, names, fmt):
|
|---|
| 8 | self.trunc = trunc
|
|---|
| 9 | self.size = size
|
|---|
| 10 | self.names = names
|
|---|
| 11 | self.fmt = fmt
|
|---|
| 12 |
|
|---|
| 13 | def decode(self, data):
|
|---|
| 14 | if self.trunc:
|
|---|
| 15 | data = data[:self.size]
|
|---|
| 16 | values = struct.unpack(self.fmt, data)
|
|---|
| 17 | if len(values) != len(self.names):
|
|---|
| 18 | raise Error, ('Format length does not match number of names', descr)
|
|---|
| 19 | rv = {}
|
|---|
| 20 | for i in range(len(values)):
|
|---|
| 21 | name = self.names[i]
|
|---|
| 22 | value = values[i]
|
|---|
| 23 | if type(name) == type(()):
|
|---|
| 24 | name, cod, dec = name
|
|---|
| 25 | value = dec(value)
|
|---|
| 26 | rv[name] = value
|
|---|
| 27 | return rv
|
|---|
| 28 |
|
|---|
| 29 | def encode(dict):
|
|---|
| 30 | list = [self.fmt]
|
|---|
| 31 | for name in self.names:
|
|---|
| 32 | if type(name) == type(()):
|
|---|
| 33 | name, cod, dec = name
|
|---|
| 34 | else:
|
|---|
| 35 | cod = dec = None
|
|---|
| 36 | value = dict[name]
|
|---|
| 37 | if cod:
|
|---|
| 38 | value = cod(value)
|
|---|
| 39 | list.append(value)
|
|---|
| 40 | rv = struct.pack(*list)
|
|---|
| 41 | return rv
|
|---|
| 42 |
|
|---|
| 43 | # Helper functions
|
|---|
| 44 | def _tofixed(float):
|
|---|
| 45 | hi = int(float)
|
|---|
| 46 | lo = int(float*0x10000) & 0xffff
|
|---|
| 47 | return (hi<<16)|lo
|
|---|
| 48 |
|
|---|
| 49 | def _fromfixed(fixed):
|
|---|
| 50 | hi = (fixed >> 16) & 0xffff
|
|---|
| 51 | lo = (fixed & 0xffff)
|
|---|
| 52 | return hi + (lo / float(0x10000))
|
|---|
| 53 |
|
|---|
| 54 | def _tostr31(str):
|
|---|
| 55 | return chr(len(str)) + str + '\0'*(31-len(str))
|
|---|
| 56 |
|
|---|
| 57 | def _fromstr31(str31):
|
|---|
| 58 | return str31[1:1+ord(str31[0])]
|
|---|
| 59 |
|
|---|
| 60 | SampleDescription = _MediaDescriptionCodec(
|
|---|
| 61 | 1, # May be longer, truncate
|
|---|
| 62 | 16, # size
|
|---|
| 63 | ('descSize', 'dataFormat', 'resvd1', 'resvd2', 'dataRefIndex'), # Attributes
|
|---|
| 64 | "l4slhh" # Format
|
|---|
| 65 | )
|
|---|
| 66 |
|
|---|
| 67 | SoundDescription = _MediaDescriptionCodec(
|
|---|
| 68 | 1,
|
|---|
| 69 | 36,
|
|---|
| 70 | ('descSize', 'dataFormat', 'resvd1', 'resvd2', 'dataRefIndex',
|
|---|
| 71 | 'version', 'revlevel', 'vendor', 'numChannels', 'sampleSize',
|
|---|
| 72 | 'compressionID', 'packetSize', ('sampleRate', _tofixed, _fromfixed)),
|
|---|
| 73 | "l4slhhhh4shhhhl" # Format
|
|---|
| 74 | )
|
|---|
| 75 |
|
|---|
| 76 | SoundDescriptionV1 = _MediaDescriptionCodec(
|
|---|
| 77 | 1,
|
|---|
| 78 | 52,
|
|---|
| 79 | ('descSize', 'dataFormat', 'resvd1', 'resvd2', 'dataRefIndex',
|
|---|
| 80 | 'version', 'revlevel', 'vendor', 'numChannels', 'sampleSize',
|
|---|
| 81 | 'compressionID', 'packetSize', ('sampleRate', _tofixed, _fromfixed), 'samplesPerPacket',
|
|---|
| 82 | 'bytesPerPacket', 'bytesPerFrame', 'bytesPerSample'),
|
|---|
| 83 | "l4slhhhh4shhhhlllll" # Format
|
|---|
| 84 | )
|
|---|
| 85 |
|
|---|
| 86 | ImageDescription = _MediaDescriptionCodec(
|
|---|
| 87 | 1, # May be longer, truncate
|
|---|
| 88 | 86, # size
|
|---|
| 89 | ('idSize', 'cType', 'resvd1', 'resvd2', 'dataRefIndex', 'version',
|
|---|
| 90 | 'revisionLevel', 'vendor', 'temporalQuality', 'spatialQuality',
|
|---|
| 91 | 'width', 'height', ('hRes', _tofixed, _fromfixed), ('vRes', _tofixed, _fromfixed),
|
|---|
| 92 | 'dataSize', 'frameCount', ('name', _tostr31, _fromstr31),
|
|---|
| 93 | 'depth', 'clutID'),
|
|---|
| 94 | 'l4slhhhh4sllhhlllh32shh',
|
|---|
| 95 | )
|
|---|
| 96 |
|
|---|
| 97 | # XXXX Others, like TextDescription and such, remain to be done.
|
|---|
