128 lines
3.8 KiB
Python
128 lines
3.8 KiB
Python
import ctypes
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from . import ogg
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from . import opus
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from .pyogg_error import PyOggError
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class OpusFileStream:
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def __init__(self, path):
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"""Opens an OggOpus file as a stream.
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path should be a string giving the filename of the file to
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open. Unicode file names may not work correctly.
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An exception will be raised if the file cannot be opened
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correctly.
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"""
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error = ctypes.c_int()
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self.of = opus.op_open_file(ogg.to_char_p(path), ctypes.pointer(error))
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if error.value != 0:
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self.of = None
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raise PyOggError("file couldn't be opened or doesn't exist. Error code : {}".format(error.value))
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#: Number of channels in audio file
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self.channels = opus.op_channel_count(self.of, -1)
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#: Total PCM Length
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self.pcm_size = opus.op_pcm_total(self.of, -1)
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#: Number of samples per second (per channel)
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self.frequency = 48000
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# The buffer size should be (per channel) large enough to
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# hold 120ms (the largest possible Opus frame) at 48kHz.
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# See https://opus-codec.org/docs/opusfile_api-0.7/group__stream__decoding.html#ga963c917749335e29bb2b698c1cb20a10
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self.buffer_size = self.frequency // 1000 * 120 * self.channels
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self.Buf = opus.opus_int16 * self.buffer_size
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self._buf = self.Buf()
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self.buffer_ptr = ctypes.cast(
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ctypes.pointer(self._buf),
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opus.opus_int16_p
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)
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#: Bytes per sample
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self.bytes_per_sample = ctypes.sizeof(opus.opus_int16)
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def __del__(self):
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if self.of is not None:
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opus.op_free(self.of)
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def get_buffer(self):
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"""Obtains the next frame of PCM samples.
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Returns an array of signed 16-bit integers. If the file
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is in stereo, the left and right channels are interleaved.
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Returns None when all data has been read.
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The array that is returned should be either processed or
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copied before the next call to :meth:`~get_buffer` or
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:meth:`~get_buffer_as_array` as the array's memory is reused for
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each call.
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"""
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# Read the next frame
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samples_read = opus.op_read(
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self.of,
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self.buffer_ptr,
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self.buffer_size,
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None
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)
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# Check for errors
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if samples_read < 0:
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raise PyOggError(
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"Failed to read OpusFileStream. Error {:d}".format(samples_read)
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)
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# Check if we've reached the end of the stream
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if samples_read == 0:
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return None
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# Cast the pointer to opus_int16 to an array of the
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# correct size
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result_ptr = ctypes.cast(
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self.buffer_ptr,
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ctypes.POINTER(opus.opus_int16 * (samples_read*self.channels))
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)
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# Convert the array to Python bytes
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return bytes(result_ptr.contents)
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def get_buffer_as_array(self):
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"""Provides the buffer as a NumPy array.
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Note that the underlying data type is 16-bit signed
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integers.
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Does not copy the underlying data, so the returned array
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should either be processed or copied before the next call
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to :meth:`~get_buffer` or :meth:`~get_buffer_as_array`.
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"""
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import numpy # type: ignore
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# Read the next samples from the stream
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buf = self.get_buffer()
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# Check if we've come to the end of the stream
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if buf is None:
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return None
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# Convert the bytes buffer to a NumPy array
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array = numpy.frombuffer(
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buf,
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dtype=numpy.int16
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)
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# Reshape the array
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return array.reshape(
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(len(buf)
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// self.bytes_per_sample
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// self.channels,
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self.channels)
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)
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