App causes max volume

[Rayrsn]

Hi I have a problem with my AirPods Pro 2, whenever the app is running the volume of the airpods is set to max (the system volume doesn't change) and lowering or increasing the volume slider doesn't change anything but as soon as i kill the app and change the volume it goes back to normal behavior. I'll be very happy to provide any logs or anything else if needed.
My phone is rooted, and the magisk module is enabled and configured exactly the way the readme was describing it.

[kavishdevar]

Could you try disabling Personalized Volume? That sometimes causes volume levels to jump randomly.

[Rayrsn]

Already tried that, but nothing changed. I’ve also tried turning off all the settings, but I’m still experiencing the same issue

[kavishdevar]

Could you share a screen recording? This seems very unlikely that the app doesn't allow you the change the volume.

[Rayrsn]

in the screen recording the volume changes depending on the volume slider but on the AirPods itself the volume is stuck at max, this happens as soon as i open the app

[kavishdevar]

Sorry, I'm a bit confused. If I understand you correctly, you are unable to swipe across the stem and control the volume? If that's the case there is an option in the app for Volume Control, try toggling that.

[Rayrsn]

No, no, that's not what I'm having a problem with. The volume buttons on my phone and the swipe function work perfectly—they both change the volume slider of my phone. The issue is that changing the volume slider has no effect; the actual volume (the decibels I'm hearing) remains at the maximum. This issue is fixed by force-closing the application

[kavishdevar]

Hey! Sorry for the very late response — but, I was unable to reproduce this. Is it still happening?

[Rayrsn]

No worries, Yes it's still a problem with my Pro 2s

[NL-TCH]

Same on my pro 2, if you need any info please let me know

[gheinzer]

Hi, I'm currently experiencing the same problem, also with the AirPods Pro 2. As I currently don't have a rooted phone and am also not really planning to root my phone, I tested the Linux app on Debian 13. Works great, apart from this problem.

The problem occurred approximately every 2nd time using the AirPods.

These are the two firmware versions which my AirPods report after sending the handshake packet:

74.2256100190000002.303
74.2256100190000002.303

In an attempt to diagnose the issue, I started playing around with some Python scripts and found one possible solution. In my testing, the packet which sets the AirPods Pro 2-specific features seemed to cause the problem. When sending the following packet, which is also used by LibrePods, the problem occurs occasionally:

04 00 04 00 4d 00 ff 00 00 00 00 00 00 00

However, when I set both bit 3 and 5 of byte 7 to 0, the problem seems to be fixed (I tested it about 20 times):

04 00 04 00 4d 00 d7 00 00 00 00 00 00 00

This works with my Python script as well as with the Linux version of LibrePods. For reference, this is my Python script:

import socket
import time

sock = socket.socket(
    socket.AF_BLUETOOTH, # type: ignore
    socket.SOCK_STREAM,
    socket.BTPROTO_L2CAP # type: ignore
)
sock.connect(("20:15:82:F1:EF:73", 0x1001))

time.sleep(0.25) # All these sleeps are necessary for some reason
# Handshake
sock.send(b"\x00\x00\x04\x00\x01\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00")
time.sleep(0.1)

# Request notifications
sock.send(b"\x04\x00\x04\x00\x0F\x00\xff\xff\xff\xff")
time.sleep(0.1)

# Enables some features on the AirPods Pro 2
sock.send(b"\x04\x00\x04\x00\x4d\x00\xD7\x00\x00\x00\x00\x00\x00\x00")
# OR sock.send(b"\x04\x00\x04\x00\x4d\x00\xFF\x00\x00\x00\x00\x00\x00\x00")
time.sleep(0.1)

... and this is my diff for LibrePods:

diff --git a/linux/airpods_packets.h b/linux/airpods_packets.h
index cbef37b..2593345 100644
--- a/linux/airpods_packets.h
+++ b/linux/airpods_packets.h
@@ -121,7 +121,7 @@ namespace AirPodsPackets
     namespace Connection
     {
         static const QByteArray HANDSHAKE = QByteArray::fromHex("00000400010002000000000000000000");
-        static const QByteArray SET_SPECIFIC_FEATURES = QByteArray::fromHex("040004004d00ff00000000000000");
+        static const QByteArray SET_SPECIFIC_FEATURES = QByteArray::fromHex("040004004d00d700000000000000");
         static const QByteArray REQUEST_NOTIFICATIONS = QByteArray::fromHex("040004000f00ffffffffff");
         static const QByteArray AIRPODS_DISCONNECTED = QByteArray::fromHex("00010000");
     }
@@ -221,4 +221,4 @@ namespace AirPodsPackets
     }
 }
 
-#endif // AIRPODS_PACKETS_H
\ No newline at end of file
+#endif // AIRPODS_PACKETS_H

Another thing I seem to have found out by accident that I didn't already find in the documenation were some of the meanings of the bits:

Offset	Functionality
0	?
1	Conversation awareness
2	Adaptive transparency
3	Something to do with this problem
4	?
5	Something to do with this problem
6	?
7	?

I hope this is helpful. Please let me know if you need any further testing or information.

[kavishdevar]

thank you very much, @gheinzer! this probably is "adaptive volume"/"personalized volume" config. this seems to popup when an recent apple device has not been paired and the actual configurations for volume based on environment haven't been written to the airpods. After I had paired it with an apple device, the volume started jumping to some reasonable volume. this happens even when I have the "personalized volume" control command set to off.

[kavishdevar]

fixed with #192