From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: [PATCH] Adds dB gain to alsa-driver, alsa-lib. Date: Thu, 15 Dec 2005 19:06:37 +0000 Message-ID: <43A1BEBD.4010304@superbug.co.uk> References: <43A1B744.2050703@superbug.co.uk> <1134673103.12086.144.camel@mindpipe> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1134673103.12086.144.camel@mindpipe> Sender: alsa-devel-admin@lists.sourceforge.net Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Lee Revell Cc: alsa-devel List-Id: alsa-devel@alsa-project.org Lee Revell wrote: > On Thu, 2005-12-15 at 18:34 +0000, James Courtier-Dutton wrote: > >>Hi, >> >>I have implemented dB gain reporting for ALSA mixer controls. >>By applying the attached patches to alsa-driver and alsa-lib, one will >>then see dB values appear in alsamixer. (I added support to alsamixer a >>long time ago) >> >>Currently, only the snd-ca0106 sound card reports the values. >> >>If the method is agreed upon, I will extend it to many more sound cards. > > > Can you briefly explain the process for adding this feature to an > existing driver (IOW say you have no docs just a vendor-obfuscated or > RE'd driver, how do you determine db_scale)? > > Lee > There is no point in RE the windows driver, because windows does not display dB values. You do it simply by measurements. You calibrate a line-in from a sound card that has documentation. Then connect it to the suspect sound card's output and measure it. Same for mic/line in. I will be implementing this dB support on creative cards first, as I have some details for them. We have docs for all AC97 controls. So hopefully that won't leave many other controls to do. Please note, my last patch has a few errors in it, so that it does not always supress the dB display with unsupported cards. I have fixed this in my own tree, but I would like full feedback first. Which sound card do you have? James ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click