Ubuntu

Total deciBel gain incorrectly reported

Reported by clubsoda on 2010-05-17
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
alsa-driver (Ubuntu)
Undecided
Daniel T Chen

Bug Description

Binary package hint: pulseaudio

This report relates to the gnome-volume-control panel applet, which reports the
total audio gain as a percentage and in deciBels whenever the user performs a
mouse-over.

The dB gain reported seems to assume that "all sliders at max" is the zero dB reference level. However, this is not always the case. For example, on my system,
Master ranges from -46.5dB to 0dB but
PCM ranges from -34.5dB to +12dB,
so if these are both set to maximum the total gain will be +12dB, not 0dB as indicated. This is important because if I use those maximum settings and play any audio which peaks above -12dB, the output will clip and sound distorted.
[i.e. For clean audio, sliders should be set to 0dB, not 100%].

This bug was initially reported against gnome-media here:-
https://bugzilla.gnome.org/show_bug.cgi?id=618551
However, a Gnome developer says the erroneous dB value shown in the tooltip comes from the pulse function pa_sw_volume_to_dB().

Cheers.

Daniel T Chen (crimsun) wrote :

This is not a pulse bug but a hardware one, and we may be able to work around it in the sound driver. Please use "apport-collect 581650" if you're running 10.04 LTS. (Otherwise, if you're using 9.10, please use "apport-collect -p alsa-base 581650".)

affects: pulseaudio (Ubuntu) → alsa-driver (Ubuntu)
Changed in alsa-driver (Ubuntu):
assignee: nobody → Daniel T Chen (crimsun)
status: New → Incomplete
clubsoda (clubsoda) wrote :

Hi Daniel,

Thanks for your reply.

I didn't want to believe this was a pulse bug but I'm even less inclined to believe ALSA could be wrong. I should have mentioned that alsamixer shows the correct dB values for each audio channel of this sound card and has been right for years. Of course, alsamixer doesn't display a "total gain", but if that was calculated as Master + PCM then it would be correct.

I'm reluctant to run an automatic tool which would "collect a lot of local information about (my) system" and post it to the web without me being able to check/edit it first. Sorry for the inconvenience but could I provide the info some other way?

For a start, from lspci -vvvnn

02:07.0 Multimedia audio controller [0401]: Ensoniq 5880B [AudioPCI] [1274:5880] (rev 02)
 Subsystem: Ensoniq Device [1274:8001]
 Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=slow >TAbort- <TAbort+ <MAbort+ >SERR- <PERR- INTx-
 Latency: 32 (3000ns min, 32000ns max)
 Interrupt: pin A routed to IRQ 11
 Region 0: I/O ports at b800 [size=64]
 Capabilities: [dc] Power Management version 1
  Flags: PMEClk- DSI+ D1- D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
  Status: D0 PME-Enable- DSel=0 DScale=0 PME-
 Kernel driver in use: ENS1371
 Kernel modules: snd-ens1371

Regards.

clubsoda (clubsoda) wrote :

Thanks for the tip.
Please see attached report.
The "ideal" mixer settings [Master at 0dB (100%), PCM at 0dB (74%)] replicate the error condition in which gnome-volume-control-applet incorrectly indicates -12dB as the total gain. Panel app should indicate 0dB instead.

Cheers.?field.comment=Thanks for the tip.
Please see attached report.
The "ideal" mixer settings [Master at 0dB (100%), PCM at 0dB (74%)] replicate the error condition in which gnome-volume-control-applet incorrectly indicates -12dB as the total gain. Panel app should indicate 0dB instead.

Cheers.?field.comment=Thanks for the tip.
Please see attached report.
The "ideal" mixer settings [Master at 0dB (100%), PCM at 0dB (74%)] replicate the error condition in which gnome-volume-control-applet incorrectly indicates -12dB as the total gain. Panel app should indicate 0dB instead.

Cheers.

clubsoda (clubsoda) wrote :

What a mess! ^^^^^^^^^^^^^^^^^^^^^^^^^
Seems to be no way for me to edit the above comment.
The comment duplication happened somehow when I attached the system info report file.

Daniel T Chen (crimsun) on 2010-06-11
Changed in alsa-driver (Ubuntu):
status: Incomplete → New
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