At Tue, 5 Sep 2006 18:46:16 -0700, Richard Fish wrote: > > Greetings, > > On my Dell Inspiron e1705 with a Sigmatel stac9200, there is a > "subwoofer" that is attached to a separate speaker pin widget. The > "Master" control only controls the 4 main speakers. > > This patch should enable the subwoofer on similarly equipped laptops, > by creating the LFE mixer controls, although at present it is coded to > be very specific to the 9200. > > It assumes that the first mono speaker pin with an amp is the > subwoofer, and I assume that no stac9200 implementation in the world > has both a Center/LFE line out _and_ an LFE speaker attached. Since > the 9200 is only a 2-channel codec to begin with, this seems > reasonable, but I've probably made other potentially incorrect > assumptions, so please review carefully. > > One problem with this patch, even if it works as intended, is that it > doesn't provide a very satisfying end-user experience, at least for > e1705 owners. The problem is that the LFE pin is almost completely > independant of the Master control, so to change the volume the user > must operate both controls, which will likely throw the audio balance > off. This can be avoided by using the PCM control, but PCM has no > mute switch. And muting Master does not mute LFE, although setting > Master to 0 does mute LFE. > > So I have another version of this patch that implements the actual LFE > channel volume as a function of the master and LFE volumes. It is > really, really fugly, but at least it provides nice behavior for the > user! It feels wrong to implement that kind of thing in the lowest > levels of the driver, but without a plugin mixer API (which I have no > clue where to start on that effort!), I don't see any other option. > > Since the alternative is so fugly, I am holding that back for now, > even though it is what I intend to use on my system. But if you are > at all interested in it, let me know and I'll clean it up a bit and > submit it. Let's merge this minimal change at first and confirm that it doesn't break other machines. I fixed the patch slightly to fit with coding style, and committed to HG tree now. I think it's fine to create a bundled volume control in the driver although a user-space solution would be more elegant. Some other codecs like AD198x already do similar tricks. But it'd be rather Dell specific, so possibly safer to sort it out with PCI vendor SSID check. > I'm not sure whether it was Sigmatel or (more likely) Dell who screwed > this up so badly, but somebody should take a beating over this. Indeed. IIRC, Intel Mac has also unsupported bass output, and possibly a similar trick would be needed... Thanks, Takashi ------------------------------------------------------------------------- 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 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
