2010/6/16 Colin Guthrie <gmane@xxxxxxxxxxxxxx> > 'Twas brillig, and Raymond Yau at 15/06/10 23:29 did gyre and gimble: > > 2010/6/16 Colin Guthrie <gmane@xxxxxxxxxxxxxx> > > > >> 'Twas brillig, and Raymond Yau at 15/06/10 00:43 did gyre and gimble: > >>> +12dB(400%) is even larger than the software gain 150% of PA > >> > >> Software gain of PA 150% = ~+11dB, so not as different as you imply. > >> > >> I've explained the cubic mapping already, so please don't use arbitrary, > >> differently calculated percentages when comparing things. It's like > >> comparing apples to oranges. > >> > >> Col > >> > >> > > When I changed the volume slider of the gnome sound applet ( select > > perference ) in Fedora 13 to maximum (i.e. PA 150% ) > > > > Seem to be bug in amixer and alsamixer > > > > alsamixer also change to 150% but press any key change back to 100% > > The fact that any key changes it back to 100% is kinda expected. It's > not designed to handle values >100% so it makes sense that it clamps it. > Annoying, but it makes sense. > The bug is alsa-lib allow alsa-pulse plugin to set the value 98304 which is outside 0 - 65536. > > > The volume range is only from 0 to 65536 > > > > why did alsa-lib allow alsa-pulse plugin to set it outside the range , > > alsamixer and amixer also display 150% ? > > > > amixer -D pulse > > Simple mixer control 'Master',0 > > Capabilities: pvolume pswitch pswitch-joined > > Playback channels: Front Left - Front Right > > Limits: Playback 0 - 65536 > > Mono: > > Front Left: Playback 98304 [150%] [on] > > Front Right: Playback 98304 [150%] [on] > > > While I agree this could be thought of as a bug, it's actually the > nicest possible display for a system that has no concept of volumes > 100%. > it is not related to 100% , the mixer application use snd_mixer_selem_get_playback_volume_range() to get min and max to calculate the number of possible step in creating the slider since the mixer application can only set the volume between min and max by snd_mixer_selem_set_playback_volume() The percentage is calculated by dividing the value by (max - min) Please study ALSA 's simpler api interface http://www.alsa-project.org/alsa-doc/alsa-lib/group___simple_mixer.html So this is a bug in alsa-lib which mislead the PA developers _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
