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flv.py
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flv.py
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from construct import *
def UBInt24(name):
"""unsigned, big endian 24-bit integer"""
return BitField(name, 24)
def UBInt24m (name):
"""This function utilizes a patched version of pyconstruct, which provides UBInt24() """
return BitStruct(name, UBInt24(name))
videodata = Struct("VideoData")
audiodata = Struct("AudioData")
flv_tagtype = Enum(Byte("FLV TagType"),
Audio = 8,
Video = 9,
Script_Data = 18,
)
scriptdata_prop = Struct("ScriptdataProperty",
PascalString("Name", UBInt16("length")),
UBInt8("Type"),
Switch("Body", lambda ctx: ctx["Type"],
{
0 : BFloat64("Value"),
2 : PascalString("Value", UBInt16("length")),
8 : LazyBound("next", lambda: scriptdata_ecmaarray),
},
default = Pass
)
)
scriptdata_ecmaarray = Struct("ScriptdataArray",
UBInt32("Length"),
MetaRepeater(lambda ctx: ctx["Length"], scriptdata_prop),
UBInt8("ObjectTerminator1"),
UBInt8("ObjectTerminator2"),
UBInt8("ObjectTerminator3"),
)
scriptdata = Struct("ScriptData",
UBInt8("NameType"),
PascalString("Name", UBInt16("length")),
UBInt8("ArrayType"),
Embed(scriptdata_ecmaarray)
)
flv_tag = Struct("Tag",
BitStruct("TypeRes",
BitField("Reserved", 2),
Flag("Filter"),
BitField("TagType", 5)
),
UBInt24m("BodySize"),
UBInt24m("Timestamp"),
UBInt8("TimestampExtended"),
UBInt24m("StreamID"),
Switch("Tag", lambda ctx: ctx["TypeRes"]["TagType"],
{
8 : audiodata,
9 : videodata,
18 : scriptdata,
},
default = Pass
)
)
flv_header = Struct("FLV Header",
String("Signature", 3),
UBInt8("Version"),
UBInt8("TypeFlags"),
UBInt32("DataOffset"),
UBInt32("PreviousTagSize")
)
flv_tag_full = Struct("FLV Tag full",
Embed(flv_tag),
UBInt32("PreviousTagSize")
)
flv = Struct("FLV",
flv_header,
MetaRepeater(1, flv_tag_full)
)