On Fri, 2011-12-30 at 16:01 +0000, Dave Williams wrote: > > > > Actually, if my reasoning above makes sense, there's no need to > > implement anything. Just remove the lfe-on-mono path from the mappings > > in profile-sets/default.conf that don't have lfe in their channel map. > > > > Can someone say why lfe-on-mono would be needed on mappings without > > separate lfe channel? > > > > > I have an example of just such a case: A Dell Inspiron 9300. There is no > lfe PCM channel, but there is a 'Master Mono' control that controls the > subwoofer level (I guess the separation is done in the analogue domain > after the DACs). > > For this computer, the 'Master' level control and 'Master Mono' level > control need to be set to (approximately) the same level to get > reasonable sound out of it. Thanks for reporting this. Now I see the point of the lfe-on-mono path. > At present I'm having to take volume control out of the hands of > pulse, as I can't persuade it to do this (I've been playing with the > analog-output-lfe-on-mono.conf path that ships with debian to no avail). > What appears to be happening is the volume chain constructed by pulse > looks like: > PCM -- Master Mono -- Master > > when it should be more like: > PCM -- Master > \- Master Mono > > The upshot being that the sub gets cranked up to max before the main > speaker levels even start to rise when controlling volume through pulse. > > There is a lot of talk on forums (e.g. ubuntu launchpad) about this > being an ALSA issue. It isn't - ALSA is reporting perfectly reasonable > dB levels. Pulse is just making a mess of working out the audio path. Sounds like a Pulseaudio bug then. I won't investigate this now, so I filed a bug: https://bugs.freedesktop.org/show_bug.cgi?id=45331 -- Tanu
