System mute more testing.
System mute more testing.
- Subject: System mute more testing.
- From: Gordon Rankin <email@hidden>
- Date: Tue, 10 Feb 2009 10:48:46 -0500
- Organization: Wavelength Audio, ltd.
Gang,
Ok I tried two other USB Audio devices with the same enumeration and
they both work. So I imagine there is something wrong with my
enumeration that is causing the system that is telling the system to use
volume on the left channel only instead of Master Channel Mute.
> What I don't understand is why OSX is Muting as a function of
> volume. If it sees the Master Channel Mute it should use that for
> Mute and not set the Mute as a function of Volume = MIN as it seems
> to be doing for the Left channel. Then if you uncheck the mute it
> resets the Left channel equal to the previous on setting.
>
> I am going to post that on the USB list as well as I get that also.
My understanding of these Audio Controls is that they should NOT be
handled by the OS at all ... they are passed down to the device over
the control pipe, and the device has to handle them in an appropriate
manner.
-- a
---------------------------------------
Andy Peters
Electronics Engineer
5511 E Rosewood St
Tucson, AZ 85711
(520) 907-2262
email@hidden
Andy,
This is correct and that is what I am doing. The I2C code (to the dac
chip) is handled by the endpoint 0 and changes the volume and mute
according to what commands are sent down the pipe. After the endpoint is
enumerated by the host computer the host then asks what the MIN, CURRENT
and MAX volume is for each channel. This is how the OS knows what to
send for those. With MUTE it is merely on or off. To change the volume
or balance the OS knows what to send for each channel and does so.
I just have to figure out what it is that is making the OS deal with
this other than the Master Channel.
I will take this over to the USB list.
Thanks all!
Gordon
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