Re: how do i enable the volume balance slider for each stereo channel?
Re: how do i enable the volume balance slider for each stereo channel?
- Subject: Re: how do i enable the volume balance slider for each stereo channel?
- From: Gagan Sidhu via Coreaudio-api <email@hidden>
- Date: Fri, 6 Dec 2024 19:24:13 -0700
hi bw,
actually my case is a PCI(-E) device driver where there are a maximum of four
streams, each with their own L/R channel that i’d like to add a balancer for.
it sounds nontrivial though. i guess i shoudln’t be surprised by this.
i wish there was an example i could use. of any kind, really.
Thanks,
Gagan
> On Dec 6, 2024, at 7:20 PM, brianw <email@hidden> wrote:
>
> I suggest looking at the arrangement of streams, channels, and properties for
> another audio interface where the balance slider appears (and is not grayed
> out).
>
> For general CoreAudio drivers, the channels can be grouped into streams of 1,
> 2, or more channels. I'd be curious whether balance only appears on streams
> with two channels, or if it appears in more configurations.
>
> In your case, it seems you have a USB audio device, so the mapping from USB
> to CoreAudio is determined by the USB Descriptors. Again, looking at some
> other audio interface that support balance should tell you what you need.
>
> Of course, once you find out the configuration that works for other
> interfaces, it may not necessarily be appropriate for your device.
>
> I've seen multichannel interfaces - eight to ten channels - where every
> channel has its own stream (they're all mono streams) or where the channels
> were grouped into an eight-channel stream (for the main outputs) plus a
> two-channel stream (for the headphones). I cannot recall whether balance
> appeared for any of these.
>
> Besides the streams and channels, looks at the properties for those aspects,
> and the values returned for those properties. You might need to use something
> like AUHAL or write your own tool to query everything on an interface that
> supports balance. That's one way to find out what you need. Of course, with a
> USB device, you'll need to know which Descriptors correspond to the CoreAudio
> properties.
>
> Brian Willoughby
>
>
> On Dec 6, 2024, at 5:42 PM, Gagan Sidhu wrote:
>> i thought this would have been taken care of by the API, but i guess i would
>> need to tell it the pins/gpio/whatever about which one is let and right.
>>
>> does anyone have good examples i could work off to add this feature? it
>> doesn’t seem that apple’s documentation or USB audio driver shows how this
>> is done.
>>
>> https://github.com/i3roly/C-Media/issues/3
>>
>> Thanks,
>> Gagan
>
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