mirror of
https://github.com/iluvcapra/wavinfo.git
synced 2026-01-01 09:20:40 +00:00
77 lines
2.2 KiB
Python
77 lines
2.2 KiB
Python
# from optparse import Option
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import struct
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from .rf64_parser import parse_rf64, RF64Context
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from typing import NamedTuple, Union, List, Optional
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class WavInfoEOFError(EOFError):
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def __init__(self, identifier, chunk_start):
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self.identifier = identifier
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self.chunk_start = chunk_start
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class ListChunkDescriptor(NamedTuple):
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signature: bytes
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children: List[Union['ChunkDescriptor', 'ListChunkDescriptor']]
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class ChunkDescriptor(NamedTuple):
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ident: bytes
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start: int
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length: int
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rf64_context: Optional[RF64Context]
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def read_data(self, from_stream) -> bytes:
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from_stream.seek(self.start)
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return from_stream.read(self.length)
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def parse_list_chunk(stream, length, rf64_context=None):
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start = stream.tell()
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signature = stream.read(4)
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children = []
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while stream.tell() - start + 8 < length:
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child_chunk = parse_chunk(stream, rf64_context=rf64_context)
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children.append(child_chunk)
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stream.seek(start + length)
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return ListChunkDescriptor(signature=signature, children=children)
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def parse_chunk(stream, rf64_context=None):
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header_start = stream.tell()
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ident = stream.read(4)
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size_bytes = stream.read(4)
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if len(ident) != 4 or len(size_bytes) != 4:
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raise WavInfoEOFError(identifier=ident, chunk_start=header_start)
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data_size = struct.unpack('<I', size_bytes)[0]
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if data_size == 0xFFFFFFFF:
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if rf64_context is None and ident in {b'RF64', b'BW64'}:
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rf64_context = parse_rf64(stream=stream, signature=ident)
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assert rf64_context is not None, \
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"Sentinel data size 0xFFFFFFFF found outside of RF64 context"
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data_size = rf64_context.bigchunk_table[ident]
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displacement = data_size
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if displacement % 2:
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displacement += 1
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if ident in {b'RIFF', b'LIST', b'RF64', b'BW64', b'list'}:
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return parse_list_chunk(stream=stream, length=data_size,
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rf64_context=rf64_context)
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else:
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data_start = stream.tell()
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stream.seek(displacement, 1)
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return ChunkDescriptor(ident=ident,
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start=data_start,
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length=data_size,
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rf64_context=rf64_context)
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