217 lines
7.7 KiB
Python
217 lines
7.7 KiB
Python
"""
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Musical Instrument Digital Interface (MIDI) audio file parser.
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Documentation:
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- Standard MIDI File Format, Dustin Caldwell (downloaded on wotsit.org)
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Author: Victor Stinner
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Creation: 27 december 2006
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"""
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from lib.hachoir_parser import Parser
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from lib.hachoir_core.field import (FieldSet, Bits, ParserError,
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String, UInt32, UInt24, UInt16, UInt8, Enum, RawBytes)
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from lib.hachoir_core.endian import BIG_ENDIAN
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from lib.hachoir_core.text_handler import textHandler, hexadecimal
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from lib.hachoir_core.tools import createDict, humanDurationNanosec
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from lib.hachoir_parser.common.tracker import NOTE_NAME
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MAX_FILESIZE = 10 * 1024 * 1024
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class Integer(Bits):
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def __init__(self, parent, name, description=None):
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Bits.__init__(self, parent, name, 8, description)
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stream = parent.stream
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addr = self.absolute_address
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value = 0
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while True:
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bits = stream.readBits(addr, 8, parent.endian)
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value = (value << 7) + (bits & 127)
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if not(bits & 128):
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break
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addr += 8
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self._size += 8
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if 32 < self._size:
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raise ParserError("Integer size is bigger than 32-bit")
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self.createValue = lambda: value
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def parseNote(parser):
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yield Enum(UInt8(parser, "note", "Note number"), NOTE_NAME)
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yield UInt8(parser, "velocity")
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def parseControl(parser):
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yield UInt8(parser, "control", "Controller number")
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yield UInt8(parser, "value", "New value")
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def parsePatch(parser):
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yield UInt8(parser, "program", "New program number")
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def parseChannel(parser):
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yield UInt8(parser, "channel", "Channel number")
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def parsePitch(parser):
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yield UInt8(parser, "bottom", "(least sig) 7 bits of value")
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yield UInt8(parser, "top", "(most sig) 7 bits of value")
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def parseText(parser, size):
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yield String(parser, "text", size)
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def formatTempo(field):
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return humanDurationNanosec(field.value*1000)
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def parseTempo(parser, size):
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yield textHandler(UInt24(parser, "microsec_quarter", "Microseconds per quarter note"), formatTempo)
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def parseTimeSignature(parser, size):
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yield UInt8(parser, "numerator", "Numerator of time signature")
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yield UInt8(parser, "denominator", "denominator of time signature 2=quarter 3=eighth, etc.")
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yield UInt8(parser, "nb_tick", "Number of ticks in metronome click")
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yield UInt8(parser, "nb_32nd_note", "Number of 32nd notes to the quarter note")
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class Command(FieldSet):
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COMMAND = {}
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for channel in xrange(16):
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COMMAND[0x80+channel] = ("Note off (channel %u)" % channel, parseNote)
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COMMAND[0x90+channel] = ("Note on (channel %u)" % channel, parseNote)
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COMMAND[0xA0+channel] = ("Key after-touch (channel %u)" % channel, parseNote)
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COMMAND[0xB0+channel] = ("Control change (channel %u)" % channel, parseControl)
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COMMAND[0xC0+channel] = ("Program (patch) change (channel %u)" % channel, parsePatch)
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COMMAND[0xD0+channel] = ("Channel after-touch (channel %u)" % channel, parseChannel)
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COMMAND[0xE0+channel] = ("Pitch wheel change (channel %u)" % channel, parsePitch)
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COMMAND_DESC = createDict(COMMAND, 0)
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COMMAND_PARSER = createDict(COMMAND, 1)
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META_COMMAND_TEXT = 1
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META_COMMAND_NAME = 3
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META_COMMAND = {
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0x00: ("Sets the track's sequence number", None),
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0x01: ("Text event", parseText),
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0x02: ("Copyright info", parseText),
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0x03: ("Sequence or Track name", parseText),
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0x04: ("Track instrument name", parseText),
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0x05: ("Lyric", parseText),
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0x06: ("Marker", parseText),
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0x07: ("Cue point", parseText),
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0x2F: ("End of the track", None),
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0x51: ("Set tempo", parseTempo),
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0x58: ("Time Signature", parseTimeSignature),
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0x59: ("Key signature", None),
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0x7F: ("Sequencer specific information", None),
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}
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META_COMMAND_DESC = createDict(META_COMMAND, 0)
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META_COMMAND_PARSER = createDict(META_COMMAND, 1)
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def createFields(self):
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yield Integer(self, "time", "Delta time in ticks")
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yield Enum(textHandler(UInt8(self, "command"), hexadecimal), self.COMMAND_DESC)
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command = self["command"].value
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if command == 0xFF:
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yield Enum(textHandler(UInt8(self, "meta_command"), hexadecimal), self.META_COMMAND_DESC)
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yield UInt8(self, "data_len")
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size = self["data_len"].value
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if size:
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command = self["meta_command"].value
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if command in self.META_COMMAND_PARSER:
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parser = self.META_COMMAND_PARSER[command]
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else:
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parser = None
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if parser:
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for field in parser(self, size):
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yield field
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else:
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yield RawBytes(self, "data", size)
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else:
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if command not in self.COMMAND_PARSER:
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raise ParserError("Unknown command: %s" % self["command"].display)
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parser = self.COMMAND_PARSER[command]
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for field in parser(self):
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yield field
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def createDescription(self):
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if "meta_command" in self:
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return self["meta_command"].display
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else:
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return self["command"].display
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class Track(FieldSet):
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def __init__(self, *args):
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FieldSet.__init__(self, *args)
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self._size = (8 + self["size"].value) * 8
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def createFields(self):
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yield String(self, "marker", 4, "Track marker (MTrk)", charset="ASCII")
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yield UInt32(self, "size")
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if True:
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while not self.eof:
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yield Command(self, "command[]")
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else:
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size = self["size"].value
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if size:
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yield RawBytes(self, "raw", size)
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def createDescription(self):
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command = self["command[0]"]
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if "meta_command" in command \
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and command["meta_command"].value in (Command.META_COMMAND_TEXT, Command.META_COMMAND_NAME) \
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and "text" in command:
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return command["text"].value.strip("\r\n")
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else:
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return ""
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class Header(FieldSet):
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static_size = 10*8
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FILE_FORMAT = {
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0: "Single track",
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1: "Multiple tracks, synchronous",
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2: "Multiple tracks, asynchronous",
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}
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def createFields(self):
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yield UInt32(self, "size")
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yield Enum(UInt16(self, "file_format"), self.FILE_FORMAT)
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yield UInt16(self, "nb_track")
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yield UInt16(self, "delta_time", "Delta-time ticks per quarter note")
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def createDescription(self):
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return "%s; %s tracks" % (
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self["file_format"].display, self["nb_track"].value)
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class MidiFile(Parser):
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MAGIC = "MThd"
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PARSER_TAGS = {
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"id": "midi",
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"category": "audio",
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"file_ext": ["mid", "midi"],
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"mime": (u"audio/mime", ),
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"magic": ((MAGIC, 0),),
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"min_size": 64,
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"description": "MIDI audio"
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}
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endian = BIG_ENDIAN
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def validate(self):
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if self.stream.readBytes(0, 4) != self.MAGIC:
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return "Invalid signature"
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if self["header/size"].value != 6:
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return "Invalid header size"
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return True
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def createFields(self):
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yield String(self, "signature", 4, r"MIDI signature (MThd)", charset="ASCII")
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yield Header(self, "header")
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while not self.eof:
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yield Track(self, "track[]")
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def createDescription(self):
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return "MIDI audio: %s" % self["header"].description
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def createContentSize(self):
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count = self["/header/nb_track"].value - 1
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start = self["track[%u]" % count].absolute_address
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# Search "End of track" of last track
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end = self.stream.searchBytes("\xff\x2f\x00", start, MAX_FILESIZE*8)
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if end is not None:
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return end + 3*8
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return None
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