Automatically detect output audio nodes

Rather then hardcoding the output node names detect them on startup.
This assumes there will be at least 2 nodes ofcourse otherwise it will
crash later

Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>

scripts/test-case-1-run.py

@@ -8,13 +8,14 @@ import sys
 import time
 
 
-def pw_dump(name):
+def pw_dump(name = None ):
     cmd_pw_dump = ["pw-dump"]
     p = subprocess.run(cmd_pw_dump, stdout=subprocess.PIPE)
     my_pw_dump = json.loads(p.stdout)
 
-    with open(name, "w") as f:
-      json.dump(my_pw_dump, f, indent=2)
+    if name != None:
+        with open(name, "w") as f:
+            json.dump(my_pw_dump, f, indent=2)
 
     return my_pw_dump
 
@@ -284,14 +285,24 @@ def start_moving_sink(my_sink_name, my_wav, my_cards, my_id_used=None):
         break
 
 
+def find_outputs():
+    dump = pw_dump()
+    outputs = []
+    for obj in dump:
+        if obj["type"] != "PipeWire:Interface:Node":
+            continue
+        if obj["info"]["props"].get("media.class") != "Audio/Sink":
+            continue
+        outputs.append(obj["info"]["props"]["node.name"])
+    return outputs
+
 if __name__ == "__main__":
     print("Run test-case 1")
 
     # To avoid interference from previous run
     kill_my_sinks()
 
-    my_sound_cards = ["alsa_output.usb-0d8c_USB_Sound_Device-00.analog-stereo",
-                      "alsa_output.platform-sound.stereo-fallback"]
+    my_sound_cards = find_outputs()
 
     # Make sound with USB sound card
     my_jackplay_id_used_A = start_sink("my-sink-A", "test300.wav", my_sound_cards[0])