helpers/mixer.py

   1 import sounddevice as sd
   2 import audioop
   3 import time
   4
   5 frame_rate   = 44100
   6 channels     = 2
   7 sample_width = 2
   8
   9 class Mixer:
  10     def __init__(self):
  11         self.stream = sd.RawOutputStream(samplerate=frame_rate,
  12                         channels=channels,
  13                         dtype='int' + str(8*sample_width), # FIXME: ?
  14                         latency="high",
  15                         blocksize=5000,
  16                         callback=self.play_callback,
  17                         )
  18         self.open_files = []
  19
  20     def add_file(self, music_file):
  21         if music_file not in self.open_files:
  22             self.open_files.append(music_file)
  23         self.start()
  24
  25     def remove_file(self, music_file):
  26         self.open_files.remove(music_file)
  27         if len(self.open_files) == 0:
  28             self.stop()
  29
  30     def stop(self):
  31         self.stream.stop()
  32
  33     def start(self):
  34         self.stream.start()
  35
  36     def play_callback(self, out_data, frame_count, time_info, status_flags):
  37         out_data_length = len(out_data)
  38         empty_data = b"\0" * out_data_length
  39         data = b"\0" * out_data_length
  40
  41         for open_file in self.open_files:
  42             file_data = open_file.play_callback(out_data_length, frame_count)
  43
  44             if data == empty_data:
  45                 data = file_data
  46             elif file_data != empty_data:
  47                 data = audioop.add(data, file_data, sample_width)
  48
  49         out_data[:] = data
  50