_libsoundio.py

"""libsoundio interface for sound output."""

# Authors: Dan McCloy <[email protected]>
#          Eric Larson <[email protected]>
#
# License: BSD (3-clause)

import ctypes

import numpy as np

# https://github.com/andrewrk/libsoundio

# Todo:
# - loop=True
# - backends
# - options file
# - fix threading weirdness


class SoundPlayer(object):

    def __init__(self, data, fs, loop=False,
                 backend=None, block_size=4096):
        self._data = np.clip(data.T, -1, 1).astype(np.float32)
        # if backend is None:
        #     from pysoundio import SoundIoBackendAlsa
        #     backend = SoundIoBackendAlsa
        self._backend = backend
        self._fs = fs
        self._block_size = block_size
        self._n_samples, self._n_channels = self._data.shape
        assert self._n_channels in (1, 2)
        self._ec_duration = self._n_samples / float(fs)
        # don't actually start it
        self._open_stream()
        self.playing = False

    def _open_stream(self):
        from pysoundio import (PySoundIo, SoundIoFormatFloat32LE,
                               SoundIoOutStream)
        self._offset = 0
        self._pysoundio = PySoundIo(backend=self._backend)
        self._started = False
        temp = self._pysoundio._start_output_stream
        self._pysoundio._start_output_stream = lambda: None
        self._pysoundio.start_output_stream(
            device_id=None, channels=self._n_channels,
            sample_rate=self._fs, block_size=self._block_size,
            dtype=SoundIoFormatFloat32LE,
            write_callback=self._callback)
        self._pysoundio._start_output_stream = temp
        stream = ctypes.cast(self._pysoundio.output['stream'],
                             ctypes.POINTER(SoundIoOutStream))
        print('Opening stream with latency %0.1fms'
              % (1000 * stream.contents.software_latency,))

    def play(self):
        if not self._started:
            self._pysoundio._start_output_stream()
            self._started = True
            self.playing = True
        else:
            self._pysoundio.pause_output_stream(False)

    def pause(self):
        self._pysoundio.pause_output_stream(True)
        self.playing = False

    def stop(self):
        self.pause()
        self._close_stream()
        self._open_stream()

    def _close_stream(self):
        if self._pysoundio is not None:
            self._pysoundio.close()
            self._pysoundio = None
            self._offset = 0

    def _callback(self, data, length):
        dlen = min(length, self._n_samples - self._offset)
        if dlen > 0:
            data[:] = self._data[self._offset:self._offset + dlen].data
            self._offset += dlen

    def delete(self):
        self.__del__()

    def __del__(self):
        self.stop()