helpers/mixer.py

   1 import sounddevice as sd
   2 import audioop
   3 import time
   4
   5 from . import Config
   6
   7 sample_width = Config.sample_width
   8 def sample_width_to_dtype(sample_width):
   9     if sample_width == 1 or sample_width == 2 or sample_width == 4:
  10         return 'int' + str(8*sample_width)
  11     else:
  12         raise "Unknown sample width"
  13
  14 def _latency(latency):
  15     if latency == "high" or latency == "low":
  16         return latency
  17     else:
  18         return float(latency)
  19
  20 class Mixer:
  21     def __init__(self):
  22         self.stream = sd.RawOutputStream(samplerate=Config.frame_rate,
  23                         channels=Config.channels,
  24                         dtype=sample_width_to_dtype(Config.sample_width),
  25                         latency=_latency(Config.latency),
  26                         blocksize=Config.blocksize,
  27                         callback=self.play_callback,
  28                         )
  29         self.open_files = []
  30
  31     def add_file(self, music_file):
  32         if music_file not in self.open_files:
  33             self.open_files.append(music_file)
  34         self.start()
  35
  36     def remove_file(self, music_file):
  37         self.open_files.remove(music_file)
  38         if len(self.open_files) == 0:
  39             self.stop()
  40
  41     def stop(self):
  42         self.stream.stop()
  43
  44     def start(self):
  45         self.stream.start()
  46
  47     def play_callback(self, out_data, frame_count, time_info, status_flags):
  48         out_data_length = len(out_data)
  49         empty_data = b"\0" * out_data_length
  50         data = b"\0" * out_data_length
  51
  52         for open_file in self.open_files:
  53             file_data = open_file.play_callback(out_data_length, frame_count)
  54
  55             if data == empty_data:
  56                 data = file_data
  57             elif file_data != empty_data:
  58                 data = audioop.add(data, file_data, sample_width)
  59
  60         out_data[:] = data
  61