mirror of
https://github.com/liberatedsystems/openCom-Companion.git
synced 2024-11-29 08:40:36 +01:00
408 lines
15 KiB
Python
408 lines
15 KiB
Python
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import copy
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import ctypes
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from typing import Optional, ByteString, List, Tuple, Callable
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import warnings
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from . import opus
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from .opus_encoder import OpusEncoder
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from .pyogg_error import PyOggError
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class OpusBufferedEncoder(OpusEncoder):
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# TODO: This could be made more efficient. We don't need a
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# deque. Instead, we need only sufficient PCM storage for one
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# whole packet. We know the size of the packet thanks to
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# set_frame_size().
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def __init__(self) -> None:
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super().__init__()
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self._frame_size_ms: Optional[float] = None
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self._frame_size_bytes: Optional[int] = None
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# Buffer contains the bytes required for the next
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# frame.
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self._buffer: Optional[ctypes.Array] = None
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# Location of the next free byte in the buffer
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self._buffer_index = 0
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def set_frame_size(self, frame_size: float) -> None:
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""" Set the desired frame duration (in milliseconds).
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Valid options are 2.5, 5, 10, 20, 40, or 60ms.
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"""
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# Ensure the frame size is valid. Compare frame size in
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# units of 0.1ms to avoid floating point comparison
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if int(frame_size*10) not in [25, 50, 100, 200, 400, 600]:
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raise PyOggError(
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"Frame size ({:f}) not one of ".format(frame_size)+
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"the acceptable values"
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)
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self._frame_size_ms = frame_size
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self._calc_frame_size()
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def set_sampling_frequency(self, samples_per_second: int) -> None:
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super().set_sampling_frequency(samples_per_second)
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self._calc_frame_size()
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def buffered_encode(self,
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pcm_bytes: memoryview,
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flush: bool = False,
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callback: Callable[[memoryview,int,bool],None] = None
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) -> List[Tuple[memoryview, int, bool]]:
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"""Gets encoded packets and their number of samples.
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This method returns a list, where each item in the list is
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a tuple. The first item in the tuple is an Opus-encoded
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frame stored as a bytes-object. The second item in the
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tuple is the number of samples encoded (excluding
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silence).
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If `callback` is supplied then this method will instead
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return an empty list but call the callback for every
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Opus-encoded frame that would have been returned as a
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list. This option has the desireable property of
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eliminating the copying of the encoded packets, which is
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required in order to form a list. The callback should
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take two arguments, the encoded frame (a Python bytes
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object) and the number of samples encoded per channel (an
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int). The user must either process or copy the data as
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the data may be overwritten once the callback terminates.
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"""
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# If there's no work to do return immediately
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if len(pcm_bytes) == 0 and flush == False:
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return [] # no work to do
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# Sanity checks
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if self._frame_size_ms is None:
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raise PyOggError("Frame size must be set before encoding")
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assert self._frame_size_bytes is not None
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assert self._channels is not None
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assert self._buffer is not None
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assert self._buffer_index is not None
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# Local variable initialisation
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results = []
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pcm_index = 0
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pcm_len = len(pcm_bytes)
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# 'Cast' memoryview of PCM to ctypes Array
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Buffer = ctypes.c_ubyte * len(pcm_bytes)
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try:
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pcm_ctypes = Buffer.from_buffer(pcm_bytes)
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except TypeError:
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warnings.warn(
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"Because PCM was read-only, an extra memory "+
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"copy was required; consider storing PCM in "+
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"writable memory (for example, bytearray "+
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"rather than bytes)."
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)
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pcm_ctypes = Buffer.from_buffer(pcm_bytes)
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# Either store the encoded packet to return at the end of the
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# method or immediately call the callback with the encoded
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# packet.
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def store_or_callback(encoded_packet: memoryview,
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samples: int,
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end_of_stream: bool = False) -> None:
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if callback is None:
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# Store the result
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results.append((
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encoded_packet,
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samples,
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end_of_stream
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))
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else:
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# Call the callback
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callback(
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encoded_packet,
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samples,
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end_of_stream
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)
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# Fill the remainder of the buffer with silence and encode it.
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# The associated number of samples are only that of actual
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# data, not the added silence.
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def flush_buffer() -> None:
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# Sanity checks to satisfy mypy
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assert self._buffer_index is not None
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assert self._channels is not None
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assert self._buffer is not None
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# If the buffer is already empty, we have no work to do
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if self._buffer_index == 0:
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return
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# Store the number of samples currently in the buffer
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samples = (
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self._buffer_index
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// self._channels
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// ctypes.sizeof(opus.opus_int16)
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)
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# Fill the buffer with silence
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ctypes.memset(
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# destination
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ctypes.byref(self._buffer, self._buffer_index),
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# value
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0,
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# count
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len(self._buffer) - self._buffer_index
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)
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# Encode the PCM
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# As at 2020-11-05, mypy is unaware that ctype Arrays
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# support the buffer protocol.
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encoded_packet = self.encode(memoryview(self._buffer)) # type: ignore
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# Either store the encoded packet or call the
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# callback
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store_or_callback(encoded_packet, samples, True)
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# Copy the data remaining from the provided PCM into the
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# buffer. Flush if required.
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def copy_insufficient_data() -> None:
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# Sanity checks to satisfy mypy
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assert self._buffer is not None
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# Calculate remaining data
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remaining_data = len(pcm_bytes) - pcm_index
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# Copy the data into the buffer.
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ctypes.memmove(
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# destination
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ctypes.byref(self._buffer, self._buffer_index),
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# source
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ctypes.byref(pcm_ctypes, pcm_index),
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# count
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remaining_data
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)
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self._buffer_index += remaining_data
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# If we've been asked to flush the buffer then do so
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if flush:
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flush_buffer()
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# Loop through the provided PCM and the current buffer,
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# encoding as we have full packets.
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while True:
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# There are two possibilities at this point: either we
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# have previously unencoded data still in the buffer or we
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# do not
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if self._buffer_index == 0:
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# We do not have unencoded data
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# We are free to progress through the PCM that has
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# been provided encoding frames without copying any
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# bytes. Once there is insufficient data remaining
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# for a complete frame, that data should be copied
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# into the buffer and we have finished.
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if pcm_len - pcm_index > self._frame_size_bytes:
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# We have enough data remaining in the provided
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# PCM to encode more than an entire frame without
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# copying any data. Unfortunately, splicing a
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# ctypes array copies the array. To avoid the
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# copy we use memoryview see
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# https://mattgwwalker.wordpress.com/2020/12/12/python-ctypes-slicing/
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frame_data = memoryview(pcm_bytes)[
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pcm_index:pcm_index+self._frame_size_bytes
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]
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# Update the PCM index
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pcm_index += self._frame_size_bytes
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# Store number of samples (per channel) of actual
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# data
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samples = (
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len(frame_data)
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// self._channels
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// ctypes.sizeof(opus.opus_int16)
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)
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# Encode the PCM
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encoded_packet = super().encode(frame_data)
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# Either store the encoded packet or call the
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# callback
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store_or_callback(encoded_packet, samples)
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else:
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# We do not have enough data to fill a frame while
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# still having data left over. Copy the data into
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# the buffer.
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copy_insufficient_data()
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return results
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else:
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# We have unencoded data.
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# Copy the provided PCM into the buffer (up until the
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# buffer is full). If we can fill it, then we can
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# encode the filled buffer and continue. If we can't
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# fill it then we've finished.
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data_required = len(self._buffer) - self._buffer_index
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if pcm_len > data_required:
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# We have sufficient data to fill the buffer and
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# have data left over. Copy data into the buffer.
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assert pcm_index == 0
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remaining = len(self._buffer) - self._buffer_index
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ctypes.memmove(
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# destination
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ctypes.byref(self._buffer, self._buffer_index),
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# source
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pcm_ctypes,
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# count
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remaining
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)
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pcm_index += remaining
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self._buffer_index += remaining
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assert self._buffer_index == len(self._buffer)
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# Encode the PCM
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encoded_packet = super().encode(
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# Memoryviews of ctypes do work, even though
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# mypy complains.
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memoryview(self._buffer) # type: ignore
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)
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# Store number of samples (per channel) of actual
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# data
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samples = (
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self._buffer_index
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// self._channels
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// ctypes.sizeof(opus.opus_int16)
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)
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# We've now processed the buffer
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self._buffer_index = 0
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# Either store the encoded packet or call the
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# callback
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store_or_callback(encoded_packet, samples)
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else:
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# We have insufficient data to fill the buffer
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# while still having data left over. Copy the
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# data into the buffer.
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copy_insufficient_data()
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return results
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def _calc_frame_size(self):
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"""Calculates the number of bytes in a frame.
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If the frame size (in milliseconds) and the number of
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samples per seconds have already been specified, then the
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frame size in bytes is set. Otherwise, this method does
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nothing.
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The frame size is measured in bytes required to store the
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sample.
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"""
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if (self._frame_size_ms is None
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or self._samples_per_second is None):
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return
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self._frame_size_bytes = (
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self._frame_size_ms
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* self._samples_per_second
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// 1000
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* ctypes.sizeof(opus.opus_int16)
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* self._channels
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)
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# Allocate space for the buffer
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Buffer = ctypes.c_ubyte * self._frame_size_bytes
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self._buffer = Buffer()
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def _get_next_frame(self, add_silence=False):
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"""Gets the next Opus-encoded frame.
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Returns a tuple where the first item is the Opus-encoded
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frame and the second item is the number of encoded samples
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(per channel).
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Returns None if insufficient data is available.
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"""
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next_frame = bytes()
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samples = 0
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# Ensure frame size has been specified
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if self._frame_size_bytes is None:
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raise PyOggError(
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"Desired frame size hasn't been set. Perhaps "+
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"encode() was called before set_frame_size() "+
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"and set_sampling_frequency()?"
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)
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# Check if there's insufficient data in the buffer to fill
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# a frame.
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if self._frame_size_bytes > self._buffer_size:
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if len(self._buffer) == 0:
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# No data at all in buffer
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return None
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if add_silence:
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# Get all remaining data
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while len(self._buffer) != 0:
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next_frame += self._buffer.popleft()
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self._buffer_size = 0
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# Store number of samples (per channel) of actual
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# data
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samples = (
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len(next_frame)
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// self._channels
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// ctypes.sizeof(opus.opus_int16)
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)
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# Fill remainder of frame with silence
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bytes_remaining = self._frame_size_bytes - len(next_frame)
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next_frame += b'\x00' * bytes_remaining
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return (next_frame, samples)
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else:
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# Insufficient data to fill a frame and we're not
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# adding silence
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return None
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bytes_remaining = self._frame_size_bytes
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while bytes_remaining > 0:
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if len(self._buffer[0]) <= bytes_remaining:
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# Take the whole first item
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buffer_ = self._buffer.popleft()
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next_frame += buffer_
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bytes_remaining -= len(buffer_)
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self._buffer_size -= len(buffer_)
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else:
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# Take only part of the buffer
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# TODO: This could be more efficiently
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# implemented. Rather than appending back the
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# remaining data, we could just update an index
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# saying where we were up to in regards to the
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# first entry of the buffer.
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buffer_ = self._buffer.popleft()
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next_frame += buffer_[:bytes_remaining]
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self._buffer_size -= bytes_remaining
|
||
|
|
# And put the unused part back into the buffer
|
||
|
|
self._buffer.appendleft(buffer_[bytes_remaining:])
|
||
|
|
bytes_remaining = 0
|
||
|
|
|
||
|
|
# Calculate number of samples (per channel)
|
||
|
|
samples = (
|
||
|
|
len(next_frame)
|
||
|
|
// self._channels
|
||
|
|
// ctypes.sizeof(opus.opus_int16)
|
||
|
|
)
|
||
|
|
|
||
|
|
return (next_frame, samples)
|