115 lines
4.2 KiB
Python
115 lines
4.2 KiB
Python
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import ctypes
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from itertools import chain
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from . import flac
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from .audio_file import AudioFile
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from .pyogg_error import PyOggError
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def _to_char_p(string):
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try:
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return ctypes.c_char_p(string.encode("utf-8"))
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except:
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return ctypes.c_char_p(string)
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def _resize_array(array, new_size):
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return (array._type_*new_size).from_address(ctypes.addressof(array))
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class FlacFile(AudioFile):
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def write_callback(self, decoder, frame, buffer, client_data):
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multi_channel_buf = _resize_array(buffer.contents, self.channels)
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arr_size = frame.contents.header.blocksize
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if frame.contents.header.channels >= 2:
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arrays = []
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for i in range(frame.contents.header.channels):
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arr = ctypes.cast(multi_channel_buf[i], ctypes.POINTER(flac.FLAC__int32*arr_size)).contents
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arrays.append(arr[:])
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arr = list(chain.from_iterable(zip(*arrays)))
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self.buffer[self.buffer_pos : self.buffer_pos + len(arr)] = arr[:]
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self.buffer_pos += len(arr)
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else:
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arr = ctypes.cast(multi_channel_buf[0], ctypes.POINTER(flac.FLAC__int32*arr_size)).contents
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self.buffer[self.buffer_pos : self.buffer_pos + arr_size] = arr[:]
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self.buffer_pos += arr_size
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return 0
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def metadata_callback(self,decoder, metadata, client_data):
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if not self.buffer:
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self.total_samples = metadata.contents.data.stream_info.total_samples
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self.channels = metadata.contents.data.stream_info.channels
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Buffer = flac.FLAC__int16*(self.total_samples * self.channels)
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self.buffer = Buffer()
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self.frequency = metadata.contents.data.stream_info.sample_rate
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def error_callback(self,decoder, status, client_data):
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raise PyOggError("An error occured during the process of decoding. Status enum: {}".format(flac.FLAC__StreamDecoderErrorStatusEnum[status]))
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def __init__(self, path):
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self.decoder = flac.FLAC__stream_decoder_new()
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self.client_data = ctypes.c_void_p()
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#: Number of channels in audio file.
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self.channels = None
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#: Number of samples per second (per channel). For
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# example, 44100.
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self.frequency = None
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self.total_samples = None
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#: Raw PCM data from audio file.
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self.buffer = None
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self.buffer_pos = 0
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write_callback_ = flac.FLAC__StreamDecoderWriteCallback(self.write_callback)
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metadata_callback_ = flac.FLAC__StreamDecoderMetadataCallback(self.metadata_callback)
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error_callback_ = flac.FLAC__StreamDecoderErrorCallback(self.error_callback)
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init_status = flac.FLAC__stream_decoder_init_file(
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self.decoder,
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_to_char_p(path), # This will have an issue with Unicode filenames
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write_callback_,
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metadata_callback_,
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error_callback_,
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self.client_data
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)
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if init_status: # error
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error = flac.FLAC__StreamDecoderInitStatusEnum[init_status]
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raise PyOggError(
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"An error occured when trying to open '{}': {}".format(path, error)
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)
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metadata_status = (flac.FLAC__stream_decoder_process_until_end_of_metadata(self.decoder))
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if not metadata_status: # error
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raise PyOggError("An error occured when trying to decode the metadata of {}".format(path))
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stream_status = (flac.FLAC__stream_decoder_process_until_end_of_stream(self.decoder))
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if not stream_status: # error
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raise PyOggError("An error occured when trying to decode the audio stream of {}".format(path))
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flac.FLAC__stream_decoder_finish(self.decoder)
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#: Length of buffer
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self.buffer_length = len(self.buffer)
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self.bytes_per_sample = ctypes.sizeof(flac.FLAC__int16) # See definition of Buffer in metadata_callback()
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# Cast buffer to one-dimensional array of chars
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CharBuffer = (
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ctypes.c_byte *
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(self.bytes_per_sample * len(self.buffer))
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)
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self.buffer = CharBuffer.from_buffer(self.buffer)
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# FLAC audio is always signed. See
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# https://xiph.org/flac/api/group__flac__stream__decoder.html#gaf98a4f9e2cac5747da6018c3dfc8dde1
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self.signed = True
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