Dne 24. 02. 21 v 12:43 Takashi Iwai napsal(a):
So far, a user control is merely storing the value, let read/write via the control API. That's all, and nothing wrong can happen just by that. Now if it interacts with other subsystem...
A more serious concern is rather the fragility of the setup; for enabling the mute LED control, you'd have to create a new user-space control, the function of the control has to be ignored by some application and some not, etc. This has to be done on each machine
You're using "ignore", but as I explained before, the user space switch will be used in the whole chain:
capture stream -> alsa-lib mute switch / silence PCM stream -> PA mute switch / silence PCM stream
So PA can use this switch like the traditional hardware mute switch.
Does it mean PA would work as of now without any change? Or does it need patching?
Yes, no PA modifications are required with my mechanism. The PA will just see the new user space control - mute switch - created in alsa-lib - which will be synced the internal PA path mute state like for the hardware mute switch. I also think that handling LEDs independently (outside the upper layers like PA) is more flexible.
Jaroslav