[wdmaudiodev] Audio 1.0 Windows volume slider

  • From: Akshaykeerti Sharma <asharma@xxxxxxxxxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 29 Aug 2017 13:41:50 -0500


Let me start by introducing myself, I am a embedded software engineer and have been trying to brave my way through the USB-Audio 1.0 class.

We designed a USB speaker using the USB audio class 1.0 spec and it seems to work pretty great till you set the bmaControls to allow the hardware to control the volume directly.

-- I am not sure if the windows audio driver is supposed to honor my request of SET_MAX/SET_MIN? I have it set to -127 to 128db and the scaling is absolutely confusing. Windows 10 returns to me a value between -60db to +60db whilst windows 7 returns a value between 60db-127db.

-- Setting the SET_MAX/SET_MIN to a custom value of say 0db - 1db (0-255) essentially locks the values at 0- 255 results in the output value scale being locked down to 0-255 but the windows volume slider scale still stuck at the defaults mentioned above.

--Now what I would desire(not sure if it is possible) is to have windows return to me a value of 0-255 or 0-100 without writing a custom driver and using the standard USB audio drivers. The second thing I would like to know is that is it possible to have consistent values being outputted from the volume slider across windows7 to windows10.

Here is a text file of the values the slider was giving me <https://pastebin.com/4j9MK90c>. On a side note, the usb-drivers seem to honor the bass/mid/treble sliders Set_Max/Set_Min I was using to debug some gains on the hardware.

Thank you for your time in reading this email.

Have a great rest of your week!



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