From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: [RFC] TLV entry for linear volume Date: Wed, 23 Aug 2006 16:07:02 +0100 Message-ID: <44EC6F16.6090807@superbug.co.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@lists.sourceforge.net Errors-To: alsa-devel-bounces@lists.sourceforge.net To: Takashi Iwai Cc: alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org Takashi Iwai wrote: > Hi, > > some codecs and dsp chips use linear volumes instead of logarithmic > one. The patch below adds a new TLV type for such a volume type. > In alsa-lib, it's converted to dB on the fly. > > If no one has objection, I'll push it together with AC97-TLV and > other similar patches after 1.0.12 release. > > > Takashi > I have not had time to look at the AC97-TLV, but if it works, I can't see why I would object. I have never come across a sound card with linear volumes. Could you identify a few of them, and also better explain the formula you are using for the conversion to dB gain. *db_gain = (long)(100.0 * 20.0 * log10((double)(volume - rec->min) / (double)(max - min))); So, 0 dB is when (volume - rec->min) / (max - min) == 1 So, for +6 dB gain, the volume will need to be higher than max? Does this sound right? In that case, maybe "max" is not a good name for it because volume can be greater than max. James ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642