Created attachment 381586 [details]
pacmd ls

1 sink(s) available.
  * index: 0
        name: <alsa_output.pci-0000_00_1b.0.analog-stereo>
        driver: <module-alsa-card.c>
        flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY FLAT_VOLUME DYNAMIC_LATENCY
        state: RUNNING
        suspend cause: 
        priority: 9959
        volume: 0:  27% 1:  27%
                0: -34.50 dB 1: -34.50 dB
                balance 0.00
        base volume:  27%
                     -34.50 dB
        volume steps: 65537

Created attachment 381587 [details]
amixer -c0

Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 43
  Mono:
  Front Left: Playback 43 [100%] [0.00dB] [on]
  Front Right: Playback 43 [100%] [0.00dB] [on]
Simple mixer control 'PCM',0
  Capabilities: pvolume pswitch penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 43
  Mono:
  Front Left: Playback 20 [47%] [0.00dB] [on]
  Front Right: Playback 20 [47%] [0.00dB] [on]

PA puts 0dB always to max amplification, ALSA does not specify where 0dB is. That causes the scales to be shifted on some cards.

Also read:

http://pulseaudio.org/wiki/PulseAudioStoleMyVolumes

(In reply to comment #3)
> PA puts 0dB always to max amplification, ALSA does not specify where 0dB is.

If ALSA doesn't specify what 0 dB is and pulseaudio depends on ALSA then it's value is also meaningless. Pulseaudio redefined a undefined but usable default with "maximum ear damage".

The core of the problem is that anything past the ALSA value of 0 dB is unusable on both PCM and Master channels. There have been other bug reports (540099, 542124) which suggest that. This causes most of the available volume range to be either too loud (15% to 27% in my case) or distorted and clipped AND too loud (from 27% upwards in my case).

This basically boils down to these scenarios:
a) Master or PCM > 0 dB causes clips
b) Master and PCM > 0 dB is excessively loud AND clips 

> That causes the scales to be shifted on some cards.
> 
> Also read:
> 
> http://pulseaudio.org/wiki/PulseAudioStoleMyVolumes  

Other than a calibration tool, I think maybe a check box that would peg the maximum (100%) volume to the ALSA equivalent of 0 dB or whatever 'Base' stands for, would effectively fix this.

(In reply to comment #4)
> (In reply to comment #3)
> > PA puts 0dB always to max amplification, ALSA does not specify where 0dB is.
> 
> If ALSA doesn't specify what 0 dB is and pulseaudio depends on ALSA then it's
> value is also meaningless. Pulseaudio redefined a undefined but usable default
> with "maximum ear damage".

ALSA has a range from x to y dB. PA now shifts that so that the range is from x-y to 0dB, making 0dB the top end of the scale and meaning max amplification. That happens to be exactly how all stereos handle this, if you every had a look.

> The core of the problem is that anything past the ALSA value of 0 dB is
> unusable on both PCM and Master channels. There have been other bug reports
> (540099, 542124) which suggest that. This causes most of the available volume
> range to be either too loud (15% to 27% in my case) or distorted and clipped
> AND too loud (from 27% upwards in my case).

That's why newer g-v-c shows the "base" volume on the slider which is where max amp is with no clipping. If you leave the slider below that everything is fine.

> > That causes the scales to be shifted on some cards.
> > 
> > Also read:
> > 
> > http://pulseaudio.org/wiki/PulseAudioStoleMyVolumes  
> 
> Other than a calibration tool, I think maybe a check box that would peg the
> maximum (100%) volume to the ALSA equivalent of 0 dB or whatever 'Base' stands
> for, would effectively fix this.  

I am sorry, but I don't think this would be a good UI. But please file a bug for this against g-v-c.

(In reply to comment #5)
> (In reply to comment #4)
> > (In reply to comment #3)
> That's why newer g-v-c shows the "base" volume on the slider which is where max
> amp is with no clipping. If you leave the slider below that everything is fine.

My version doesn't (gnome-media-2.28.1-3.fc12.x86_64) indicate where the 'Base' volume is on the slider. It only shows 100%. I can't tell where the 'Base' volume is.

Now I've noticed something funny: g-v-c shows and available range of over 100% but pavucontrol doesn't. Both pavucontrol's and g-v-c's sliders are synchronised properly but I can select a "volume" of over 100% in g-v-c. Pavucontrol's available range ends at 100% but the value beside the slider goes over 100% when I change it in g-v-c.

Yes, pavucontrol limits its range more restricively than g-v-c does.

g-v-c unfortunately shows the base volume only for recording, not for playback. Will reassign this bug to g-v-c now, so that this is added, too.

Hmm, will file this as upstream.

(In reply to comment #7)
> Yes, pavucontrol limits its range more restricively than g-v-c does.

Just to note that explicitly: g-v-c is right in showing the scale up to 150%, since digital amp is often quite useful.

*** Bug 542437 has been marked as a duplicate of this bug. ***

https://bugzilla.gnome.org/show_bug.cgi?id=606325

(In reply to comment #5)
> (In reply to comment #4)
> > (In reply to comment #3)
> > > PA puts 0dB always to max amplification, ALSA does not specify where 0dB is.
> > 
> > If ALSA doesn't specify what 0 dB is and pulseaudio depends on ALSA then it's
> > value is also meaningless. Pulseaudio redefined a undefined but usable default
> > with "maximum ear damage".
> 
> ALSA has a range from x to y dB. PA now shifts that so that the range is from
> x-y to 0dB, making 0dB the top end of the scale and meaning max amplification.
> That happens to be exactly how all stereos handle this, if you every had a
> look.

There's something that occurred to me. Wouldn't it mean that the ALSA values follow the same scheme? i.e. 0 dB means max amplification. This would explain why values above 0 dB cause clipping.

Even if values a little above 0 dB don't cause clipping this would, at least in my case, make the whole volume range usable. Currently, only a third is usable and that gives me 3 values:
  0% mute
 17% medium
 30% loud and clipped
>30% unusable

(In reply to comment #9)
> Just to note that explicitly: g-v-c is right in showing the scale up to 150%,
since digital amp is often quite useful.    
It would be useful if the input to that digital amp wasn't clipped to all hell.

(In reply to comment #12)

> There's something that occurred to me. Wouldn't it mean that the ALSA values
> follow the same scheme? i.e. 0 dB means max amplification. This would explain
> why values above 0 dB cause clipping.

ALSA does not define what 0dB means. Some drivers set 0dB to max amp, others to max amp with no clipping. Others set it so that it reflects some "sane" output level, i.e. some defined output voltage. Others do the same but pick a different output voltage, since there is no standard for it. For even others 0dB means "not amplified".

So, there is really no defined meaning what 0dB refers to. PA now shifts that all so that 0dB is always max hw amplification. But because 0dB often actually *does* have a meaning, but which is very much card dependant we do export that value and call it "base".

> 
> Even if values a little above 0 dB don't cause clipping this would, at least in
> my case, make the whole volume range usable. Currently, only a third is usable
> and that gives me 3 values:
>   0% mute
>  17% medium
>  30% loud and clipped
> >30% unusable

3 values? There should be enough selection between 0-30%?

So are you complaining that too much of the full scale is already in the clipping range?

> 
> (In reply to comment #9)
> > Just to note that explicitly: g-v-c is right in showing the scale up to 150%,
> since digital amp is often quite useful.    
> It would be useful if the input to that digital amp wasn't clipped to all hell.    

If you ever played a DVD you might have noticed that they usually are recorded at a very low volume level and digital amp often does *not* result in clipping and distortion. For those cases we do allow it.

(In reply to comment #13)
> (In reply to comment #12)
> 
> ALSA does not define what 0dB means. Some drivers set 0dB to max amp, others to
> max amp with no clipping. Others set it so that it reflects some "sane" output
> level, i.e. some defined output voltage. Others do the same but pick a
> different output voltage, since there is no standard for it. For even others
> 0dB means "not amplified".
> 
> So, there is really no defined meaning what 0dB refers to. PA now shifts that
> all so that 0dB is always max hw amplification. But because 0dB often actually
> *does* have a meaning, but which is very much card dependant we do export that
> value and call it "base".
> 

It would be nice if the volume controls limited themselves automatically to the usable range, since composite volume control took that control from me. 


> > Even if values a little above 0 dB don't cause clipping this would, at least in
> > my case, make the whole volume range usable. Currently, only a third is usable
> > and that gives me 3 values:
> >   0% mute
> >  17% medium
> >  30% loud and clipped
> > >30% unusable
> 
> 3 values? There should be enough selection between 0-30%?
> 
> So are you complaining that too much of the full scale is already in the
> clipping range?

Yes. Over 70% percent of the range is clipped, as I've mentioned several times before.

> > (In reply to comment #9)
> > > Just to note that explicitly: g-v-c is right in showing the scale up to 150%,
> > since digital amp is often quite useful.    
> > It would be useful if the input to that digital amp wasn't clipped to all hell.    
> 
> If you ever played a DVD you might have noticed that they usually are recorded
> at a very low volume level and digital amp often does *not* result in clipping
> and distortion. For those cases we do allow it.    

You also allow it for cases where it _does_ result in clipping.