Bug 113630

Summary:	Preset for "DRC" settings results in low volume sound output
Product:	[openSUSE] SUSE LINUX 10.0	Reporter:	Joerg Reuter <jreuter>
Component:	Sound	Assignee:	Takashi Iwai <tiwai>
Status:	RESOLVED FIXED	QA Contact:	E-mail List <qa-bugs>
Severity:	Normal
Priority:	P5 - None
Version:	Beta 3
Target Milestone:	---
Hardware:	PowerPC
OS:	All
Whiteboard:
Found By:	SUSE Technical Services	Services Priority:
Business Priority:		Blocker:	---
Marketing QA Status:	---	IT Deployment:	---

Description Joerg Reuter 2005-08-28 11:48:19 UTC

The snd_powermac driver has two controls for "DRC": "DRC on/off" and "DRC
Range". Granted, I don't know what that means. However, the default after
installation is DRC enabled and DRC Range set to 0, which results in very low
volume output until either "DRC" gets "muted" or "DRC Range" set to a high
value. I'd suggest to set this to a reasonable value when initializing the driver.

Comment 1 Takashi Iwai 2005-08-29 09:48:25 UTC

DRC means dynamic range compression.
It's set on as default to prevent crashing your amplifier or headphone by too
loud tones at the first time.

It's OK to me to change the default drc range value.  Please let me know the
value you think safe on all devices and still reasonablly high enough (since I
have no ppc hardware here).

Comment 2 Joerg Reuter 2005-08-29 18:23:53 UTC

I've played a bit with this stuff now. 60% is okay with the built in speakers, 
BeyerDynamic DT431 headphones and Sony MDR-EX71 earplugs. However, I noticed
something else strange: DRC gets disabled automatically as soon as I plug in
headphones and enabled again when I unplug them. Kind of defeats the purpose,
shouldn't it be the other way around? (Playing with the other toggles does not
change that...)

Comment 3 Takashi Iwai 2005-08-30 12:56:32 UTC

Hmm, right, DRC is automatically off when headphone/line-out is plugged in.
So, this control is apparently for only internal speakers although toggling
on/off enables the DRC again.  It's confusing.
I'll disable this auto-toggling feature and raise the default.
Could you show the output of
    amixer get "DRC Range"
??

Comment 4 Joerg Reuter 2005-08-30 19:53:21 UTC

Sure:

Simple mixer control 'DRC Range',0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 239
  Mono: 145 [61%]

BTW, enabling DRC with the headphones plugged in will have the expected effect
on the headphones as well. The auto toggling results in a somewhat reasonable
volume on the internal speakers once you've adjusted DRC Range, but when you
plug in the headphones your ears are gonne fall off... On the other hand, while
having the internal speakers on maximum volume sure sounds terrible it won't
damage your equipment or sense of hearing. That's why I think that DRC toggling
was simply the wrong way around. On the other hand, maybe it is TiBook specific
and later PowerBooks or iBooks have this reversed, indeed... Disabling
auto-toggling would be a good idea in the case, indeed. MacOS X does not seem to
use auto-toggling either, as far as I can tell.

Comment 5 Takashi Iwai 2005-09-01 15:57:19 UTC

OK, then the question is whether we need DRC on per default or not.

This is surely good for internal speakers, so turning on as default would make
sense if we assume that the default is with internal speaker.

Comment 6 Joerg Reuter 2005-09-01 18:42:33 UTC

Either option is fine with me: enabled and pre-set with 145, or disabled. Since
the default volume and mixer settings are pretty safe anyway I'd say disabling
DRC won't hurt.

Comment 7 Takashi Iwai 2005-09-02 16:57:34 UTC

The patch is on kernel CVS now.