Codec Zero sound card

.asoundrc

@@ -1,17 +1,13 @@
-pcm.my_sound_device {
-	type hw
-	card USB
-#	card PCH
-#	card Headphones
-	device 0
+#pcm.!default {
+#        type hw
+#        card Zero
+##        card USB
+#}
+
+pcm.hw0mix {
+    type dmix
+    ipc_key 1939 # must be unique
+    slave { pcm "hw:Zero" }
 }
 
-pcm.my_sound_device_with_converter {
-	type plug
-	slave {
-		pcm my_sound_device
-		format S16_LE
-	        channels 2
-		rate 48000
-	}
-}
+pcm.!default hw0mix

dog-trainer.py

@@ -4,16 +4,13 @@ from datetime import datetime
 import subprocess
 import sys
 
-# PLAY_DEVICE = "default"  # Playback/recording through the PulseAudio sound server
-# REC_DEVICE = "default"  # Playback/recording through the PulseAudio sound server
-
-PLAY_DEVICE = "my_sound_device_with_converter"  # as defined in '~/.asoundrc'
-REC_DEVICE = "my_sound_device"  # as defined in '~/.asoundrc'
+PLAY_DEVICE = "default"  # as defined in '~/.asoundrc'
+REC_DEVICE = "plughw:Zero"  # as listed by 'arecord -L'
 
 MAX_RECORDING_TIME = 30  # limit recordings to only e.g. 30 seconds long
-TRIM_RECORDING_END = 0.8  # remove the clicking noise from the end of recordings
+TRIM_RECORDING_END = 0.6  # remove the clicking noise from the end of recordings
 RECORD_BUTTON_PRESS_TIME = 2  # pressing and holding a button longer then e.g. 2 seconds triggers recording otherwise playing
-PINS = [17, 23]  # listen to changes on this GPIOs e.g. [4, 17, 23, 0, 5, 6]
+PINS = [17, 22, 27]  # listen to changes on this GPIOs e.g. [4, 17, 23, 0, 5, 6]
 GPIO.setmode(GPIO.BCM)  # use BCM pin layout
 GPIO.setwarnings(False)
 
@@ -40,8 +37,7 @@ def terminate_recording(proc, pin):
             "-of",
             "default=noprint_wrappers=1:nokey=1",
             f"recording_temp_{pin}.wav",
-        ],
-        stdout=subprocess.PIPE,
+        ], check=True, stdout=subprocess.PIPE,
     ).stdout.decode("utf-8")
     subprocess.call(
         [
@@ -66,7 +62,8 @@ def terminate_recording(proc, pin):
 
 
 def play(file):
-    subprocess.call(["aplay", "-D", PLAY_DEVICE, file])
+    print(f"Playing {file}")
+    subprocess.run(["aplay", f"-D{PLAY_DEVICE}", file], check=True)
 
 
 def play_sound(pin):
@@ -86,20 +83,17 @@ def record_sound(pin):
     proc = subprocess.Popen(
         [
             "arecord",
-            "-D",
-            REC_DEVICE,
-            "-f",
-            "S16_LE",
-            "-r",
-            "16000",
-            "-c",
-            "1",
-            "-d",
-            f"{MAX_RECORDING_TIME}",
+            f"-D{REC_DEVICE}",
+            "-fS16_LE",
+            "-r48000",
+            "-c2",
+            f"-d{MAX_RECORDING_TIME}",
             f"recording_temp_{pin}.wav",
         ]
     )
     print(f"Recording in progress (max {MAX_RECORDING_TIME} seconds)...")
+    time.sleep(0.5)
+    play_beep()
     wait_for_button_release_or_timeout(pin, MAX_RECORDING_TIME)
     print("GPIO went HIGH - terminating recording")
     play_beep()
@@ -121,7 +115,6 @@ def handle_pin(pin):
 
     if time.time() - timeout_start >= RECORD_BUTTON_PRESS_TIME:
         # Pin was LOW for longer time; recording
-        play_beep()
         record_sound(pin)
     else:
         # Pin was LOW for shorter time; playing

dog-trainer.service

@@ -1,6 +1,7 @@
 [Unit]
 Description=Dog Trainer
-After=sound.target
+After=sound-init.service
+Requires=sound-init.service
 
 [Service]
 Type=simple

sound-init.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=Sound Initialization Service
+PartOf=dog-trainer.service
+
+[Service]
+Type=simple
+User=pi
+Group=pi
+ExecStart=/bin/sh -c 'cat /dev/zero | aplay -Ddefault -fS16_LE -c2 -r 48000'
+Restart=always
+RestartSec=3
+
+[Install]
+WantedBy=multi-user.target