1 files changed, 50 insertions, 0 deletions

diff --git a/helpers/mixer.py b/helpers/mixer.py
new file mode 100644
index 0000000..9e8179a
--- /dev/null
+++ b/helpers/mixer.py
@@ -0,0 +1,50 @@
+import sounddevice as sd
+import audioop
+import time
+
+frame_rate   = 44100
+channels     = 2
+sample_width = 2
+
+class Mixer:
+    def __init__(self):
+        self.stream = sd.RawOutputStream(samplerate=frame_rate,
+                        channels=channels,
+                        dtype='int' + str(8*sample_width), # FIXME: ?
+                        latency="high",
+                        blocksize=5000,
+                        callback=self.play_callback,
+                        )
+        self.open_files = []
+
+    def add_file(self, music_file):
+        if music_file not in self.open_files:
+            self.open_files.append(music_file)
+        self.start()
+
+    def remove_file(self, music_file):
+        self.open_files.remove(music_file)
+        if len(self.open_files) == 0:
+            self.stop()
+
+    def stop(self):
+        self.stream.stop()
+
+    def start(self):
+        self.stream.start()
+
+    def play_callback(self, out_data, frame_count, time_info, status_flags):
+        out_data_length = len(out_data)
+        empty_data = b"\0" * out_data_length
+        data = b"\0" * out_data_length
+
+        for open_file in self.open_files:
+            file_data = open_file.play_callback(out_data_length, frame_count)
+
+            if data == empty_data:
+                data = file_data
+            elif file_data != empty_data:
+                data = audioop.add(data, file_data, sample_width)
+
+        out_data[:] = data
+