2012-05-07 20:06, Arun Raghavan skrev: > On Mon, 2012-05-07 at 13:02 -0700, David Henningsson wrote: >> 2012-05-07 03:47, Tanu Kaskinen skrev: >>> On Mon, 2012-05-07 at 09:46 +0530, Arun Raghavan wrote: >>>> On Tue, 2012-05-01 at 20:09 +0300, Tanu Kaskinen wrote: >>>>> Changes in v2: >>>>> - Call the mapping a generic 4-channel input mapping >>>>> instead of a 4-channel mic array mapping. The mapping >>>>> will be used also by sound cards that have two stereo >>>>> input jacks, so in those cases talking about mic arrays >>>>> is wrong. >>>>> - Added a comment about using the "hw" device name. >>>>> >>>>> BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=45813 >>>>> --- >>>>> src/modules/alsa/alsa-mixer.c | 1 + >>>>> src/modules/alsa/mixer/profile-sets/default.conf | 9 +++++++++ >>>>> 2 files changed, 10 insertions(+) >>>>> >>>>> diff --git a/src/modules/alsa/alsa-mixer.c b/src/modules/alsa/alsa-mixer.c >>>>> index abb12ee..8b54f75 100644 >>>>> --- a/src/modules/alsa/alsa-mixer.c >>>>> +++ b/src/modules/alsa/alsa-mixer.c >>>>> @@ -3888,6 +3888,7 @@ static int mapping_verify(pa_alsa_mapping *m, const pa_channel_map *bonus) { >>>>> { "analog-surround-61", N_("Analog Surround 6.1") }, >>>>> { "analog-surround-70", N_("Analog Surround 7.0") }, >>>>> { "analog-surround-71", N_("Analog Surround 7.1") }, >>>>> + { "analog-4-channel-input", N_("Analog 4-channel Input") }, >>>> Since this is limited to some specific hardware, shouldn't we set up >>>> udev rules instead of always probing? >>> "All devices supporting 4-channel input" isn't very specific hardware >>> IMHO, >> I agree with Arun on this one. Besides, it is not obvious to me what the >> channel mapping should be either, and couldn't that vary between >> different 4-channel hardware? Is the aux* just causing all inputs to be >> added for whatever the client wants to have...? >> >>> and I doubt udev can be used to query the amount of supported >>> channels. >> Hmm...that raises a thought I didn't consider before. Why don't we do >> this in alsa-lib? If this varies between devices, we could create e g, >> for 4-channel mic hardware A, we set up a alsa-lib ttable to have >> "front" record two channels, the two left ones mixing in to the left and >> the two right ones mixing into the right. Or in what way do we actually >> use all four channels today? > The separate mics may eventually be useful for beamforming and > associated processing. Would your approach require changes to alsa-lib > again if we wanted to do that? If yes, it might be better to let > PulseAudio take care of this. The attached patch (untested!) would just add the possibility to do a four-to-two channel mixdown when you open front:%f (for the cards explicitly selected in the patch), so for four-channel beamforming you could still open hw:%f in four channel mode. // David -------------- next part -------------- A non-text attachment was scrubbed... Name: four-channel-mixdown-alsalib.patch Type: text/x-patch Size: 1584 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20120508/da419194/attachment.bin>
