From owner-freebsd-usb@freebsd.org Mon Oct 10 17:38:20 2016 Return-Path: Delivered-To: freebsd-usb@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id B96E3C0C86B for ; Mon, 10 Oct 2016 17:38:20 +0000 (UTC) (envelope-from hps@selasky.org) Received: from mail.turbocat.net (mail.turbocat.net [IPv6:2a01:4f8:d16:4514::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 848143C3 for ; Mon, 10 Oct 2016 17:38:20 +0000 (UTC) (envelope-from hps@selasky.org) Received: from laptop015.home.selasky.org (unknown [62.141.129.119]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.turbocat.net (Postfix) with ESMTPSA id 282F31FE022; Mon, 10 Oct 2016 19:38:10 +0200 (CEST) Subject: Re: snd_uaudio multichannel problems To: =?UTF-8?Q?Goran_Meki=c4=87?= , freebsd-usb@freebsd.org References: <20161010173118.4lff7phfx2zqm6wz@hal9000.meka.no-ip.org> From: Hans Petter Selasky Message-ID: <660971d2-0857-97b8-e047-b9853609b425@selasky.org> Date: Mon, 10 Oct 2016 19:43:07 +0200 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <20161010173118.4lff7phfx2zqm6wz@hal9000.meka.no-ip.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Oct 2016 17:38:20 -0000 On 10/10/16 19:31, Goran Mekić wrote: > Hello, > > I own 2 18ch audio interfaces, and both have the same symptoms described in https://lists.freebsd.org/pipermail/freebsd-questions/2016-October/273960.html. Since I wrote that mail, I did a little research. My hypotesis is that audio is 9 times faster as driver is handling 18 channels like they are 2. Also, if something for stereo stream is sent to all outputs, you expect to get some small and very high pitched output on all out jack, and I do. Also, playing with http://manuals.opensound.com/developer/singen.c.html revealed to me that if SNDCTL_DSP_CHANNELS is set to number different than the number of actual channels in a working stack (laptop and it's internal audio interface, in my case), you get difference in pitch and volume. > > I didn't poke snd_uaudio code, yet, as I didn't do any kernel development before, but I'm affraid the number of kernel developers with multichannel audio interfaces is quite low, so I don't mind getting my hands dirty, but I'd love to get some advice before I attack this problem. Thank you! > > Regards, > meka > Hi, Up to 127 channels are supported using USB audio. Which version of FreeBSD are you using? What does dmesg say about your audio device. Channel numbers above 8, are only supported through bitperfect modes. Then you'll need something like virtual_oss, to subdivide the audio device into several 2-channel or 1-channel DSP devices. svn --username anonsvn --password anonsvn \ checkout svn://svn.turbocat.net/i4b/trunk/virtual_oss cd virtual_oss make all install man virtual_oss --HPS