[pulseaudio-discuss] [RFC PATCH 0/3] alsa: Support for only-multichannel devices

Raymond Yau superquad.vortex2 at gmail.com
Mon Jul 28 16:32:47 PDT 2014

>>  >
>>  >  * Exact-channels can be set to false to allow devices to be opened
>>  >    any channel count instead of just the one specified in the channel
>> map.
>> Do these kind of devices need more than one profile if they have same
>> channel Min and channel Max and both are larger than two ?
> This seems to be the common case that we're trying to handle here, and it
will end up with the profiles "off", "generic input" "generic output" and
"generic output + generic input".
>> How can user capture stereo from a FireWire device which only support 6
>> channels
> With this patch set, PA will setup a default channel map. I e, recording
stereo will mean recording from the first two channels.
>> capture as pulseaudio downmix 6 channels to stereo for playback
>> stream?
>> Can pulseaudio provide a control to select  stereo capture from first
>> Jack, second jack .... ?
> You'll need module-remap-source for that.

Will this change affect the 4 ch capture device ?

How do user select stereo or 4ch capture ?


USB Mixer: usb_id=0x14152000, ctrlif=1, ctlerr=0
Card: OmniVision Technologies, Inc. USB Camera-B4.04.27.1 at
usb-0000:00:1d.7-4, high
  Unit: 3
    Control: name="Mic Capture Volume", index=0
    Info: id=3, control=2, cmask=0xf, channels=4, type="S16"
    Volume: min=0, max=1, dBmin=0, dBmax=0

>> The problems are non standard volume control names
> The firewire drivers currently don't implement volume controls the normal
ALSA mixer way.
> For some other cards (PCI, USB), you're right that the names are
sometimes non standard. Please fix that in ALSA. :-)

Do pulseaudio really support 4 ch capture ?
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