From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raymond Yau Subject: Re: wrong decibel data? Date: Mon, 14 Jun 2010 17:54:15 +0800 Message-ID: References: <4BFE7840.4070004@ladisch.de> <20100613135349.GB5818@tango.0pointer.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-vw0-f51.google.com (mail-vw0-f51.google.com [209.85.212.51]) by alsa0.perex.cz (Postfix) with ESMTP id 0681224686 for ; Mon, 14 Jun 2010 11:54:16 +0200 (CEST) Received: by vws8 with SMTP id 8so500058vws.38 for ; Mon, 14 Jun 2010 02:54:15 -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 2010/6/14 James Courtier-Dutton > On 14 June 2010 09:33, Colin Guthrie wrote: > > 'Twas brillig, and Raymond Yau at 14/06/10 01:25 did gyre and gimble: > >> if your sound card have ac97 codec ., you can use audacity to record the > >> output from hw:0,0 and you will see clipping occur when you set "PCM" > volume > >> above 0dB > > > > So the standard response is "don't do that then" :) > > > > That's why the base volume is shown to the user via GUIs so that they > > can gauge the best point on the slider to use. Currently there is no > > indication with alsa sliders at which point the 0dB "sweet spot" lies. > > > > What do you mean. > If you use "alsamixer", dB values are shown so it is easy to find the > 0dB "sweet spot". > I think it is pulse audio that hides this information when it combines > two alsa mixer controls into one pulseaudio control. > The base volume seem to be the software 0dB point , (no software gain/atten), but the user want the hardware 0dB point (no hardware gain/atten if the hardware can provide hardware gain This hardware 0dB point is extremely important when you want to record using line in and line out