make loop=True required for constant play, add test code

Author: timchinowsky

shared-module/audiocore/RawSample.c

@@ -56,7 +56,7 @@ void audioio_rawsample_reset_buffer(audioio_rawsample_obj_t *self,
     bool single_channel_output,
     uint8_t channel) {
 
-    self->buffer_index = 0;
+    // self->buffer_index = 0;
 }
 
 audioio_get_buffer_result_t audioio_rawsample_get_buffer(audioio_rawsample_obj_t *self,
@@ -82,7 +82,8 @@ audioio_get_buffer_result_t audioio_rawsample_get_buffer(audioio_rawsample_obj_t
             *buffer = self->buffer + self->len / 2 * self->buffer_index;
         }
         self->buffer_index = 1 - self->buffer_index;
-        return GET_BUFFER_MORE_DATA;
+        // return GET_BUFFER_MORE_DATA;
+        return GET_BUFFER_DONE;
     }
 }
 

tests/circuitpython-manual/live_audio/mix.py

@@ -0,0 +1,67 @@
+import audiocore
+import audiopwmio
+import audiomixer
+import board
+import array
+import time
+import math
+
+CHANNELS = 2
+RATE = 8000
+SAMPLE_TYPE = "H"
+OFFSET = 2**15 - 1
+BUFFER_SIZE = 640
+SINGLE_BUFFER = True
+LOOP = True
+
+# (frequency, amp_left, amp_right)
+VOICES = ((200, 1, 0), (400, 0, 1), (100, 1, 1))
+
+
+def play(
+    voices=VOICES,
+    channels=CHANNELS,
+    rate=RATE,
+    sample_type=SAMPLE_TYPE,
+    offset=OFFSET,
+    buffer_size=BUFFER_SIZE,
+    single_buffer=SINGLE_BUFFER,
+    loop=LOOP,
+):
+    waves = []
+    samples = []
+    for v in voices:
+        print(v)
+        sample_length = int(rate // v[0])
+        wave = array.array(sample_type, [offset] * sample_length * channels)
+        for i in range(0, sample_length):
+            if channels == 1:
+                wave[i] = int(
+                    math.sin(math.pi * 2 * i / sample_length) * v[1] * (2**15 - 1) + offset
+                )
+            else:
+                wave[2 * i] = int(
+                    math.sin(math.pi * 2 * i / sample_length) * v[1] * (2**15 - 1) + offset
+                )
+                wave[2 * i + 1] = int(
+                    math.sin(math.pi * 2 * i / sample_length) * v[2] * (2**15 - 1) + offset
+                )
+        waves.append(wave)
+        samples.append(
+            audiocore.RawSample(
+                wave, sample_rate=rate, channel_count=channels, single_buffer=single_buffer
+            )
+        )
+    mixer = audiomixer.Mixer(
+        voice_count=len(voices),
+        sample_rate=rate,
+        channel_count=channels,
+        bits_per_sample=16,
+        samples_signed=False,
+        buffer_size=buffer_size,
+    )
+    pwm = audiopwmio.PWMAudioOut(left_channel=board.D12, right_channel=board.D13)
+    pwm.play(mixer)
+    for i in range(len(samples)):
+        mixer.voice[i].play(samples[i], loop=loop)
+        mixer.voice[i].level = 0.5