From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Adam M. Costello" Date: Wed, 23 Feb 2000 00:10:44 +0000 Subject: Where are my 32 mixer levels? (SB16) Message-Id: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sound@vger.kernel.org After poking around various sound documents and driver source code, it looks like my SoundBlaster (a "Creative ViBRA16C PnP" according to pnpdump) is supposed to have 32 different PCM volume levels, but in fact there are only 8. Levels 0..11 are all silent, then there is a jump from 11 to 12. Levels 12..14 are all the same, then there is another jump from 24 to 25, then 37/38, 49/50, 62/63, 75/76, 88/89. I'm using aumix -w to set the level, under Linux 2.2.14. I have the following aliases set in modutils.conf: alias char-major-14 soundcore # basic sound capabilities alias sound-slot-0 sb # main sound card hardware driver alias sound-service-0-0 sound # mixer taken care of by sound.o alias sound-service-0-2 sb # uart support part of sb alias sound-service-0-3 sound # /dev/dsp & /dev/audio support in sound.o alias sound-service-0-6 sound # /dev/sndstat support in sound.o Does anyone knows whether I'm really supposed to have 32 different levels, and if so, what might be going wrong? Also, does anyone know what this 0..100 scale is supposed to mean? By doing listening experiments where I compare the effect of aumix -w to the effect of multiplying the audio samples by a constant, I've determined that the seven non-silent levels have output amplitudes roughly in the proportion 1:2:4:7:10:16:23, which is bizarre. The first two jumps are +6 dB, the next is about +5 dB, and the last three are about +3.5 dB. I'd really like to understand what the mixer levels mean, so that if I pipe my sound through a filter that scales down the samples to avoid overflow, I can compensate for it by increasing the mixer level the proper amount. Can anyone offer any clues? Thanks, AMC