""" Musical Instrument Digital Interface (MIDI) audio file parser. Documentation: - Standard MIDI File Format, Dustin Caldwell (downloaded on wotsit.org) Author: Victor Stinner Creation: 27 december 2006 """ from hachoir_parser import Parser from hachoir_core.field import (FieldSet, Bits, ParserError, String, UInt32, UInt24, UInt16, UInt8, Enum, RawBits, RawBytes) from hachoir_core.endian import BIG_ENDIAN from hachoir_core.text_handler import textHandler, hexadecimal from hachoir_core.tools import createDict, humanDurationNanosec from hachoir_parser.common.tracker import NOTE_NAME MAX_FILESIZE = 10 * 1024 * 1024 class Integer(Bits): def __init__(self, parent, name, description=None): Bits.__init__(self, parent, name, 8, description) stream = parent.stream addr = self.absolute_address value = 0 while True: bits = stream.readBits(addr, 8, parent.endian) value = (value << 7) + (bits & 127) if not(bits & 128): break addr += 8 self._size += 8 if 32 < self._size: raise ParserError("Integer size is bigger than 32-bit") self.createValue = lambda: value def parseNote(parser): yield Enum(UInt8(parser, "note", "Note number"), NOTE_NAME) yield UInt8(parser, "velocity") def parseControl(parser): yield UInt8(parser, "control", "Controller number") yield UInt8(parser, "value", "New value") def parsePatch(parser): yield UInt8(parser, "program", "New program number") def parseChannel(parser, size=1): yield UInt8(parser, "channel", "Channel number") def parsePitch(parser): yield UInt8(parser, "bottom", "(least sig) 7 bits of value") yield UInt8(parser, "top", "(most sig) 7 bits of value") def parseText(parser, size): yield String(parser, "text", size) def parseSMPTEOffset(parser, size): yield RawBits(parser, "padding", 1) yield Enum(Bits(parser, "frame_rate", 2), {0:"24 fps", 1:"25 fps", 2:"30 fps (drop frame)", 3:"30 fps"}) yield Bits(parser, "hour", 5) yield UInt8(parser, "minute") yield UInt8(parser, "second") yield UInt8(parser, "frame") yield UInt8(parser, "subframe", "100 subframes per frame") def formatTempo(field): return humanDurationNanosec(field.value*1000) def parseTempo(parser, size): yield textHandler(UInt24(parser, "microsec_quarter", "Microseconds per quarter note"), formatTempo) def parseTimeSignature(parser, size): yield UInt8(parser, "numerator", "Numerator of time signature") yield UInt8(parser, "denominator", "denominator of time signature 2=quarter 3=eighth, etc.") yield UInt8(parser, "nb_tick", "Number of ticks in metronome click") yield UInt8(parser, "nb_32nd_note", "Number of 32nd notes to the quarter note") class Command(FieldSet): COMMAND = {} for channel in xrange(16): COMMAND[0x80+channel] = ("Note off (channel %u)" % channel, parseNote) COMMAND[0x90+channel] = ("Note on (channel %u)" % channel, parseNote) COMMAND[0xA0+channel] = ("Key after-touch (channel %u)" % channel, parseNote) COMMAND[0xB0+channel] = ("Control change (channel %u)" % channel, parseControl) COMMAND[0xC0+channel] = ("Program (patch) change (channel %u)" % channel, parsePatch) COMMAND[0xD0+channel] = ("Channel after-touch (channel %u)" % channel, parseChannel) COMMAND[0xE0+channel] = ("Pitch wheel change (channel %u)" % channel, parsePitch) COMMAND_DESC = createDict(COMMAND, 0) COMMAND_PARSER = createDict(COMMAND, 1) META_COMMAND_TEXT = 1 META_COMMAND_NAME = 3 META_COMMAND = { 0x00: ("Sets the track's sequence number", None), 0x01: ("Text event", parseText), 0x02: ("Copyright info", parseText), 0x03: ("Sequence or Track name", parseText), 0x04: ("Track instrument name", parseText), 0x05: ("Lyric", parseText), 0x06: ("Marker", parseText), 0x07: ("Cue point", parseText), 0x20: ("MIDI Channel Prefix", parseChannel), 0x2F: ("End of the track", None), 0x51: ("Set tempo", parseTempo), 0x54: ("SMPTE offset", parseSMPTEOffset), 0x58: ("Time Signature", parseTimeSignature), 0x59: ("Key signature", None), 0x7F: ("Sequencer specific information", None), } META_COMMAND_DESC = createDict(META_COMMAND, 0) META_COMMAND_PARSER = createDict(META_COMMAND, 1) def __init__(self, *args, **kwargs): if 'prev_command' in kwargs: self.prev_command = kwargs['prev_command'] del kwargs['prev_command'] else: self.prev_command = None self.command = None FieldSet.__init__(self, *args, **kwargs) def createFields(self): yield Integer(self, "time", "Delta time in ticks") next = self.stream.readBits(self.absolute_address+self.current_size, 8, self.root.endian) if next & 0x80 == 0: # "Running Status" command if self.prev_command is None: raise ParserError("Running Status command not preceded by another command.") self.command = self.prev_command.command else: yield Enum(textHandler(UInt8(self, "command"), hexadecimal), self.COMMAND_DESC) self.command = self["command"].value if self.command == 0xFF: yield Enum(textHandler(UInt8(self, "meta_command"), hexadecimal), self.META_COMMAND_DESC) yield UInt8(self, "data_len") size = self["data_len"].value if size: command = self["meta_command"].value if command in self.META_COMMAND_PARSER: parser = self.META_COMMAND_PARSER[command] else: parser = None if parser: for field in parser(self, size): yield field else: yield RawBytes(self, "data", size) else: if self.command not in self.COMMAND_PARSER: raise ParserError("Unknown command: %s" % self["command"].display) parser = self.COMMAND_PARSER[self.command] for field in parser(self): yield field def createDescription(self): if "meta_command" in self: return self["meta_command"].display else: return self.COMMAND_DESC[self.command] class Track(FieldSet): def __init__(self, *args): FieldSet.__init__(self, *args) self._size = (8 + self["size"].value) * 8 def createFields(self): yield String(self, "marker", 4, "Track marker (MTrk)", charset="ASCII") yield UInt32(self, "size") cur = None if True: while not self.eof: cur = Command(self, "command[]", prev_command=cur) yield cur else: size = self["size"].value if size: yield RawBytes(self, "raw", size) def createDescription(self): command = self["command[0]"] if "meta_command" in command \ and command["meta_command"].value in (Command.META_COMMAND_TEXT, Command.META_COMMAND_NAME) \ and "text" in command: return command["text"].value.strip("\r\n") else: return "" class Header(FieldSet): static_size = 10*8 FILE_FORMAT = { 0: "Single track", 1: "Multiple tracks, synchronous", 2: "Multiple tracks, asynchronous", } def createFields(self): yield UInt32(self, "size") yield Enum(UInt16(self, "file_format"), self.FILE_FORMAT) yield UInt16(self, "nb_track") yield UInt16(self, "delta_time", "Delta-time ticks per quarter note") def createDescription(self): return "%s; %s tracks" % ( self["file_format"].display, self["nb_track"].value) class MidiFile(Parser): MAGIC = "MThd" PARSER_TAGS = { "id": "midi", "category": "audio", "file_ext": ["mid", "midi"], "mime": (u"audio/mime", ), "magic": ((MAGIC, 0),), "min_size": 64, "description": "MIDI audio" } endian = BIG_ENDIAN def validate(self): if self.stream.readBytes(0, 4) != self.MAGIC: return "Invalid signature" if self["header/size"].value != 6: return "Invalid header size" return True def createFields(self): yield String(self, "signature", 4, r"MIDI signature (MThd)", charset="ASCII") yield Header(self, "header") while not self.eof: yield Track(self, "track[]") def createDescription(self): return "MIDI audio: %s" % self["header"].description def createContentSize(self): count = self["/header/nb_track"].value - 1 start = self["track[%u]" % count].absolute_address # Search "End of track" of last track end = self.stream.searchBytes("\xff\x2f\x00", start, MAX_FILESIZE*8) if end is not None: return end + 3*8 return None