2010/6/16 Colin Guthrie <gmane@xxxxxxxxxxxxxx>
> 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 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%.
>
> That said, the correct fix would be a nice mechanism for marking the
> 100% mark. e.g. specifying the limits as a triplet, lower, normal (aka
> 100%) and max.
>
> AFAIK, no such system is currently in place.
>
> An alternative would be to scale the alsa volume control to the full
> range, e.g. make 0 - 98304[1] the range it accepts. But this sucks as
> the percentage shown in alsa is not the same as the percentage shown in
> other GUIs.
>
> In a practical sense, the current setup is probably less problematic
> than the latter suggestion.
>
> Col
>
> [1] FWIW, this precice value will likely change. I've not yet actioned
> it but it's likely to be fixed at +11dB which IIRC is slightly above
> 150%. 11dB is just a figure that we felt was "sensible" with regards to
> GUI consistency and I'll try and push this out ot all the UIs I can.
>
>
>
You have made a big mistake , please study the source code of alsamixer and
amixer
Simple mixer control 'PCM',0
Capabilities: pvolume pswitch pswitch-joined
Playback channels: Front Left - Front Right
Limits: Playback 0 - 31
Mono:
Front Left: Playback 31 [100%] [12.00dB] [on]
Front Right: Playback 31 [100%] [12.00dB] [on]
control.39 {
comment.access 'read write'
comment.type INTEGER
comment.count 2
comment.range '0 - 31'
comment.dbmin -3450
comment.dbmax 1200
iface MIXER
name 'PCM Playback Volume'
value.0 31
value.1 31
}
---------------------------------------------------------------------
Simple mixer control 'PCM',0
Capabilities: pvolume pswitch pswitch-joined
Playback channels: Front Left - Front Right
Limits: Playback 0 - 31
Mono:
Front Left: Playback 23 [74%] [0.00dB] [on]
Front Right: Playback 23 [74%] [0.00dB] [on]
control.39 {
comment.access 'read write'
comment.type INTEGER
comment.count 2
comment.range '0 - 31'
comment.dbmin -3450
comment.dbmax 1200
iface MIXER
name 'PCM Playback Volume'
value.0 23
value.1 23
}
The percentage displayed below the vertical slider in alsamixer and the
percentage after the dB values are the percentage of the current step / the
total number of step
so you cannot get any percentage > 100% in alsamixer and amixer
snd_mixer_selem_get_playback_volume_range() of PCM return min =0 and max=
31
at 0dB the percentage is 23/32 about 74% since 0dB is step 23 in step 0
-34.5dB , step31 is 12dB (the difference between step is 1.5dB
This percentage in alsamixer and amixer is not those volume scale which you
described BASE_VOLUME or PA_NORM
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