Fedora 11 nerfed my mixer

Lennart Poettering mzerqung at 0pointer.de
Fri Apr 24 14:18:44 UTC 2009

On Fri, 24.04.09 12:53, Bill Crawford (billcrawford1970 at gmail.com) wrote:

> > those magic keys, and then there is master, and then there is PCM. My
> > plan is to collapse them all into a single slider which is possible if
> > we have dB information about the sliders. The resulting slider would
> > be the multiplication of the seperate sliders. This would both
> > increase the range and the granularity of the overall volume slider
> > and also allows us to fix the mixer initialization issue a bit since
> > we would control both PCM and Master.
> ...this is not the right way to go.

You are wrong.

> Often, doing so with (say) a high-level CD input, will lead to clipping 
> somewhere in the hardware as soon as you add another signal. You have more than 
> one volume control for a reason.


Not sure if I get what you exactly want, but let me say three things: 

Firstly I believe that playing audio cds via the classic 'analog' path
is obsolete. CDs should be ripped sector by sector and played as PCM
streams to the sound card. Only that allows flexibly moving cd audio
between different sound cards and makes it possible to handle external
usb disk drives correctly.

Secondly, the logic to select the volumes for the various sliders is
going from the outermost slider to the innermost always coming closer
to the actual volume you want to achieve. That means that the
outermost (hopefully analog) slider will do the 'biggest' part of the
volume adjustment while the remaining sliders (usually digital) are
mostly initialized to 0dB or shortly below. That's the best thing to
avoid clipping in the hw.

Thirdly: of course if you mix several 16bit streams into one 16bit
stream you might end up with clipping. It's not as tragic as it sounds
however: most of them time only one stream plays, and usually for good
CDs the average signal level has enough headroom to allow mixing at
least two streams without clipping. And finally there are plans to add
a simple range comrpession scheme to the mixing process for the cases
where clipping might happen.

> > This should fix a lot of problems for a lot of people. However it will
> > of course also annoy Mr. Lerwick. But I fear I have to live with that
> > I guess.
> This is - perhaps understandably, from reading the preceding discussion - being 
> completely dismissive of a real user with, from his point of view, a valid 
> complaint and use case. What makes him (and I, and others) upset is the clear 
> fact that you're not interested in "supporting" our use-cases *at all* ... and 
> we don't have any particularly bizarre needs.

As mentioned there's always 'alsamixer'.

Please don't claim I wouldn't listen. You are confusing 'listening'
with 'agreeing'. I am aware of this uncomon use-case of using a sound
card as a hw mixer for line-in. And I have decided it is a use-case
that is out of scope for PA.

Now, what about you folks and listening? You keep repeating the same
thing over and over again. And I respond the same and the same thing
over and over again: we don't make the uncommon uses impossible. All
we do is we make the common uses simple. And we leave enough tools for
the uncommon uses: 'alsamixer' or a similar tool that exposes the full
ALSA control set.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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