I had in my openhab.log the recurring message
2025-09-27 09:49:59.561 [WARN ] [nternal.javasound.JavaSoundAudioSink] - Cannot determine master volume level - assuming 100%
linked with a DSL action:
playSound("enhancedjavasound", "a.mp3", new PercentType(100))
on a non-Mac system. After debugging it by changing bundles/org.openhab.core.audio/src/main/java/org/openhab/core/audio/internal/javasound/JavaSoundAudioSink.java:
@@ -238,7 +238,10 @@ public class JavaSoundAudioSink extends AudioSinkAsync {
Mixer.Info[] infos = AudioSystem.getMixerInfo();
for (Mixer.Info info : infos) {
Mixer mixer = AudioSystem.getMixer(info);
+ logger.error("LOOPING info=" + info.toString() + " mixer=" + mixer.toString() + "source lines amount="
+ + mixer.getSourceLines().length + " target lines amount=" + mixer.getTargetLines().length);
if (mixer.isLineSupported(Port.Info.SPEAKER)) {
+ logger.error("LINE Info.SPEAKER is supported");
the logs said:
2025-09-26 09:30:16.339 [ERROR] [nternal.javasound.JavaSoundAudioSink] - LOOPING info=Port Headphones [hw:0], version 6.6.60-v7+ mixer=com.sun.media.sound.PortMixer@1cc7e13 source lines amount=0 target lines amount=0
2025-09-26 09:30:16.346 [ERROR] [nternal.javasound.JavaSoundAudioSink] - LOOPING info=Port vc4hdmi [hw:1], version 6.6.60-v7+ mixer=com.sun.media.sound.PortMixer@13c0ed7 source lines amount=0 target lines amount=0
2025-09-26 09:30:16.359 [ERROR] [nternal.javasound.JavaSoundAudioSink] - LOOPING info=Headphones [default], version 6.6.60-v7+ mixer=com.sun.media.sound.DirectAudioDevice@11bd1f2 source lines amount=0 target lines amount=0
2025-09-26 09:30:16.368 [ERROR] [nternal.javasound.JavaSoundAudioSink] - LOOPING info=Headphones [plughw:0,0], version 6.6.60-v7+ mixer=com.sun.media.sound.DirectAudioDevice@b4bb56 source lines amount=0 target lines amount=0
2025-09-26 09:30:16.375 [ERROR] [nternal.javasound.JavaSoundAudioSink] - LOOPING info=vc4hdmi [plughw:1,0], version 6.6.60-v7+ mixer=com.sun.media.sound.DirectAudioDevice@1614368 source lines amount=0 target lines amount=0
2025-09-26 09:30:16.377 [ERROR] [nternal.javasound.JavaSoundAudioSink] - A Cannot determine master volume level - assuming 100%
That is, enhancedjavasound has no “lines” where and none of the lines can act as Port.Info.SPEAKER.
So I just removed , new PercentType(100) from playSound("enhancedjavasound", …) and the warning disappearedtdi.