A module to parse/generate MediaDescription handles as used by QuickTime. Only
generic, video and audio implemented for now.
diff --git a/Mac/Lib/lib-toolbox/MediaDescr.py b/Mac/Lib/lib-toolbox/MediaDescr.py
new file mode 100644
index 0000000..3c73820
--- /dev/null
+++ b/Mac/Lib/lib-toolbox/MediaDescr.py
@@ -0,0 +1,97 @@
+# 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 = apply(struct.pack, tuple(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.