""" FLAC (audio) parser Documentation: * http://flac.sourceforge.net/format.html Author: Esteban Loiseau <baal AT tuxfamily.org> Creation date: 2008-04-09 """ from hachoir.parser import Parser from hachoir.field import FieldSet, String, Bit, Bits, UInt16, UInt24, RawBytes, Enum, NullBytes from hachoir.stream import BIG_ENDIAN, LITTLE_ENDIAN from hachoir.core.tools import createDict from hachoir.parser.container.ogg import parseVorbisComment class VorbisComment(FieldSet): endian = LITTLE_ENDIAN createFields = parseVorbisComment class StreamInfo(FieldSet): static_size = 34 * 8 def createFields(self): yield UInt16(self, "min_block_size", "The minimum block size (in samples) used in the stream") yield UInt16(self, "max_block_size", "The maximum block size (in samples) used in the stream") yield UInt24(self, "min_frame_size", "The minimum frame size (in bytes) used in the stream") yield UInt24(self, "max_frame_size", "The maximum frame size (in bytes) used in the stream") yield Bits(self, "sample_hertz", 20, "Sample rate in Hertz") yield Bits(self, "nb_channel", 3, "Number of channels minus one") yield Bits(self, "bits_per_sample", 5, "Bits per sample minus one") yield Bits(self, "total_samples", 36, "Total samples in stream") yield RawBytes(self, "md5sum", 16, "MD5 signature of the unencoded audio data") class SeekPoint(FieldSet): def createFields(self): yield Bits(self, "sample_number", 64, "Sample number") yield Bits(self, "offset", 64, "Offset in bytes") yield Bits(self, "nb_sample", 16) class SeekTable(FieldSet): def createFields(self): while not self.eof: yield SeekPoint(self, "point[]") class MetadataBlock(FieldSet): "Metadata block field: http://flac.sourceforge.net/format.html#metadata_block" BLOCK_TYPES = { 0: ("stream_info", "Stream info", StreamInfo), 1: ("padding[]", "Padding", None), 2: ("application[]", "Application", None), 3: ("seek_table", "Seek table", SeekTable), 4: ("comment", "Vorbis comment", VorbisComment), 5: ("cue_sheet[]", "Cue sheet", None), 6: ("picture[]", "Picture", None), } BLOCK_TYPE_DESC = createDict(BLOCK_TYPES, 1) def __init__(self, *args, **kw): FieldSet.__init__(self, *args, **kw) self._size = 32 + self["metadata_length"].value * 8 try: key = self["block_type"].value self._name, self._description, self.handler = self.BLOCK_TYPES[key] except KeyError: self.handler = None def createFields(self): yield Bit(self, "last_metadata_block", "True if this is the last metadata block") yield Enum(Bits(self, "block_type", 7, "Metadata block header type"), self.BLOCK_TYPE_DESC) yield UInt24(self, "metadata_length", "Length of following metadata in bytes (doesn't include this header)") block_type = self["block_type"].value size = self["metadata_length"].value if not size: return try: handler = self.BLOCK_TYPES[block_type][2] except KeyError: handler = None if handler: yield handler(self, "content", size=size * 8) elif self["block_type"].value == 1: yield NullBytes(self, "padding", size) else: yield RawBytes(self, "rawdata", size) class Metadata(FieldSet): def createFields(self): while not self.eof: field = MetadataBlock(self, "metadata_block[]") yield field if field["last_metadata_block"].value: break class Frame(FieldSet): SAMPLE_RATES = { 0: "get from STREAMINFO metadata block", 1: "88.2kHz", 2: "176.4kHz", 3: "192kHz", 4: "8kHz", 5: "16kHz", 6: "22.05kHz", 7: "24kHz", 8: "32kHz", 9: "44.1kHz", 10: "48kHz", 11: "96kHz", 12: "get 8 bit sample rate (in kHz) from end of header", 13: "get 16 bit sample rate (in Hz) from end of header", 14: "get 16 bit sample rate (in tens of Hz) from end of header", } def createFields(self): yield Bits(self, "sync", 14, "Sync code: 11111111111110") yield Bit(self, "reserved[]") yield Bit(self, "blocking_strategy") yield Bits(self, "block_size", 4) yield Enum(Bits(self, "sample_rate", 4), self.SAMPLE_RATES) yield Bits(self, "channel_assign", 4) yield Bits(self, "sample_size", 3) yield Bit(self, "reserved[]") # FIXME: Finish frame header parser class Frames(FieldSet): def createFields(self): while not self.eof: yield Frame(self, "frame[]") # FIXME: Parse all frames return class FlacParser(Parser): "Parse FLAC audio files: FLAC is a lossless audio codec" MAGIC = b"fLaC\x00" PARSER_TAGS = { "id": "flac", "category": "audio", "file_ext": ("flac",), "mime": ("audio/x-flac",), "magic": ((MAGIC, 0),), "min_size": 4 * 8, "description": "FLAC audio", } endian = BIG_ENDIAN def validate(self): if self.stream.readBytes(0, len(self.MAGIC)) != self.MAGIC: return "Invalid magic string" return True def createFields(self): yield String(self, "signature", 4, charset="ASCII", description="FLAC signature: fLaC string") yield Metadata(self, "metadata") yield Frames(self, "frames")