music_sampler/mixer.py

   1 import sounddevice as sd
   2 import audioop
   3 import time
   4
   5 from .helpers import Config, error_print
   6
   7 sample_width = Config.sample_width
   8
   9 def sample_width_to_dtype():
  10     if sample_width == 1 or sample_width == 2 or sample_width == 4:
  11         return 'int' + str(8*sample_width)
  12     else:
  13         error_print("Unknown sample width, setting default value 2.")
  14         Config.sample_width = 2
  15         return 'int16'
  16
  17 def _latency(latency):
  18     if latency == "high" or latency == "low":
  19         return latency
  20     else:
  21         return float(latency)
  22
  23 class Mixer:
  24     def __init__(self):
  25         self.stream = sd.RawOutputStream(
  26                 samplerate=Config.frame_rate,
  27                 channels=Config.channels,
  28                 dtype=sample_width_to_dtype(),
  29                 latency=_latency(Config.latency),
  30                 blocksize=Config.blocksize,
  31                 callback=self.play_callback)
  32         self.open_files = []
  33
  34     def add_file(self, music_file):
  35         if music_file not in self.open_files:
  36             self.open_files.append(music_file)
  37         self.start()
  38
  39     def remove_file(self, music_file):
  40         if music_file in self.open_files:
  41             self.open_files.remove(music_file)
  42         if len(self.open_files) == 0:
  43             self.stop()
  44
  45     def stop(self):
  46         self.stream.stop()
  47
  48     def start(self):
  49         self.stream.start()
  50
  51     def play_callback(self, out_data, frame_count, time_info, status_flags):
  52         out_data_length = len(out_data)
  53         empty_data = b"\0" * out_data_length
  54         data = b"\0" * out_data_length
  55
  56         for open_file in self.open_files:
  57             file_data = open_file.play_callback(out_data_length, frame_count)
  58
  59             if data == empty_data:
  60                 data = file_data
  61             elif file_data != empty_data:
  62                 data = audioop.add(data, file_data, sample_width)
  63
  64         out_data[:] = data
  65