From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raymond Yau Subject: Re: wrong decibel data? Date: Sat, 17 Apr 2010 08:40:13 +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-pz0-f202.google.com (mail-pz0-f202.google.com [209.85.222.202]) by alsa0.perex.cz (Postfix) with ESMTP id 94A121037EC for ; Sat, 17 Apr 2010 02:40:15 +0200 (CEST) Received: by pzk40 with SMTP id 40so2349742pzk.23 for ; Fri, 16 Apr 2010 17:40:14 -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? > if you had read studied the bug report "On my Compaq R3070 laptop setting Master and Master Mono controls to 0 does not result in no sound out. I still get audio at a low level." The user only set Master and Master mono controls to 0. http://www.analog.com/en/audiovideo-products/audio-codecs/ad1981b/products/= product.html Refer to Figure 1 THe functional BLock Diagram , you should notice that there is another volume control in the audio path from DAC to LINE_OUT The Master Volume and Master mono control have dB range from -46.5dB to 0dB But the PCM Out volume control has dB range of -34.5dB to +12 dB That is you have to sum the atten of the hardware volume controls in the audio path