From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raymond Yau Subject: Re: wrong decibel data? Date: Sat, 10 Apr 2010 08:11:36 +0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mail-pw0-f51.google.com (mail-pw0-f51.google.com [209.85.160.51]) by alsa0.perex.cz (Postfix) with ESMTP id DC7D91037F1 for ; Sat, 10 Apr 2010 02:11:37 +0200 (CEST) Received: by pwj8 with SMTP id 8so2216754pwj.38 for ; Fri, 09 Apr 2010 17:11:36 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: ALSA Development Mailing List List-Id: alsa-devel@alsa-project.org 2010/4/9 Nicolo' Chieffo > On Fri, Apr 9, 2010 at 1:11 AM, Raymond Yau > wrote: > > Mute Capable (1 bit) reports if the respective amplifier is capable of > > muting. Muting implies a =96infinity gain (no sound passes), but the ac= tual > > performance is determined by the hardware. > > > > http://thread.gmane.org/gmane.linux.alsa.devel/39262/focus=3D16100 > > I think you missed the point, I'll explain again. > I'm not complaining that at 0% the audio is not mute, as the bug you > linked. > > >>> Clemens Ladisch (developer) 2004-11-09 09:26 > >>> The AD1981B's datasheet says that the maximum attenuation is 46.5 = dB > >>> (which conforms to the AC'97 specification). > >>> To mute, use Mute. > > In fact my problem is that at 0% I get mute, but I shouldn't (as > reported by that developer), since the max attenuation is not -inf, > but -48 dB. > So if you prefer, you could see this issue from a different point of > view: at -48 dB the audio should be still audible, but it's not. > > so you have to decide where the issue resides (but definitely not in > pulseaudio) > a) it is ok that the audio is mute at 0% (in this case you have to > declare -inf dB) > b) the audio level is really -48 dB (in this case the volume shouldn't > be cut off completely, but simply quite low) > Which one do you prefer? > http://en.wikipedia.org/wiki/Decibel In electronics, the decibel is often used to express power or amplitude ratios (gains), in preference to arithmetic ratios or percentages. One advantage is that the total decibel gain of a series of components (such as amplifers and attenuators) can be calculated simply by summing the decibel gains of the individual components.