At Sun, 20 Apr 2008 02:00:51 +0200, Lennart Poettering wrote: > > On Tue, 15.04.08 12:17, Takashi Iwai (tiwai@xxxxxxx) wrote: > > > > Now the thing is, this mostly works fine, however on one of my > > > devices, a pair of external Logitech USB speakers (ID 046d:0a04 > > > Logitech, Inc. V20 portable speakers), the dB scale seems to be > > > totally bogus. According to ALSA volume ranges from -41 dB to > > > +3dB. However, Every setting > -41 dB makes audio awfully > > > loud. Really, really fucking loud that is. Disco loud. As loud that > > > the speakers start jump around centimeters due to the massive > > > vibrations. Setting the volume to 0dB with those speakers really makes > > > you fear you are trashing them. > > > > This is typically a problem of your usb hardware. The USB descriptor > > gives the dB level information and the usb-audio driver simply passes > > the given data as dB scale information. But, the hardware actually > > doesn't behave as it states. Unfortunately a frequent problem with > > cheap USB audio devices. > > > > So, it's definitely no universal ALSA problem. Please don't mix up. > > My understanding is that the dB values of this USB device are relative > to its maximum gain, and as such consistent in itself. Does the USB > spec define the reference level for the dB values? Not clearly. IIRC, it's against the line level... > If not there's probably nothing wrong with the USB device. However, > then I guess I am doomed with my task to find good defaults in a > generic way for mixer controls. I'm afraid so, too. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
