From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Gareus Subject: Focusrite Scarlett 18i6 mixer Date: Fri, 18 Jan 2013 05:05:15 +0100 Message-ID: <50F8C9FB.3010200@gareus.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mo-p00-ob.rzone.de (mo-p00-ob.rzone.de [81.169.146.162]) by alsa0.perex.cz (Postfix) with ESMTP id DD401261658 for ; Fri, 18 Jan 2013 05:05:22 +0100 (CET) Received: from [10.8.0.6] (rg42.org [85.214.110.134]) by smtp.strato.de (joses mo29) (RZmta 31.12 AUTH) with ESMTPA id u07fbcp0I3Kez8 for ; Fri, 18 Jan 2013 05:05:21 +0100 (CET) List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Hi, I've started to reverse engineer the 18i6 mixer protocol and came up with a proof-of-concept test script which includes documentation: https://github.com/x42/scarlettmixer Except for a few fixed controls and switches, the 18i6's mixer and router is [likely] too complex to be exposed via ALSA's mixer interface. AFAICT it'll require a dedicated control application - like hdspmixer - in order to make full use of it. The current proof-of-concept uses pyUSB to send URB control messages and therefore requires root access. It will also not work while the device is in use (by snd-usb-audio). A dedicated ioctl interface - similar to SNDRV_HDSP_ - should be added to ALSA. However, it is yet unclear to me how much of the protocol should be moved to kernel-space. Anyway, the script can be used to configure the device, save settings to it and subsequently use those settings with snd-usb-audio and Martin's patch. Thoughts, comments? robin PS. the same protocol may apply to other Focusrite Scalett USB2 devices such as the 8i6 - some of the factory-reset traces hint at that, but I would not know.