'Splain please re: mixer, alsa, pulseaudio and tvtime??

Mikkel L. Ellertson mikkel at infinity-ltd.com
Sat Jul 25 01:10:19 UTC 2009


William Case wrote:
> 
> The question is more complex than that.  TVTime now has two mixer
> options: OSS and Alsa.  The OSS channel names correspond to a list
> supplied by tvtime.xml and to the list in alsamixer.  For Alsa I have
> two choices of protocol or formulations to define the mixer and channel
> used, either a)<option name="MixerDevice" value="default/Line"/> or b)
> <option name="MixerDevice" value=<DEVICE[:CH]".  On my machine tvtime
> seems to accept b) only.
> 
> I have only been able to find "Line" or "CD" suggested as possible
> channels [:CH] for the alsa formulation.  Note the intial letter
> capitalization of the channel name in Alsa versus the all lower case in
> OSS.
> 
> So, can I use the same channel names, with a capitalized first letter,
> as are listed for OSS or is there a new list of channel names that only
> applies to Alsa?
> 
> The second part of the question I was asking was what channels do I want
> to choose.  I have a lot of info here about what each of the channels is
> *supposed* to do.  But I have received so much conflicting advice, and
> tried so many possible combinations, I wanted to start fresh being able
> to think through for myself what the settings should be.  The various
> guis I have all seem to confuse the issue(s) rather than clarify.  The
> fact that I have a PCIe bus with internal sound seems to greatly confuse
> the issue and outdates much of the google information I have found.
> 
> In the end, this all may be a bug caused by faulty or outdated drivers.
> But first I would like to work my way through to a solid conclusion
> before being castigated by maintainers for not knowing what I am talking
> about.
> 
Ok let me define a couple of things. You may want to run
"man amixer" for a full explanation.

amixer info - provides information about the default card.
-----------------------------------------------------------
amixer scontrols - provides names of the controls for choice a.
Simple mixer control 'Line',0
would be channel "Line"

-----------------------------------------------------------
amixer scontrols - provides names of the controls for the f
amixer controls - provides number/description for choice b.

numid=19,iface=MIXER,name='Line Playback Volume'
would be channel 19.
-----------------------------------------------------------
amixer contents - gives much more information about the controls
                  and the type of settings. It may help decide what
                  control to use.
-----------------------------------------------------------
aplay -l - lists the audio output cards in the system.

Now, amixer defaults to sound card 0 (hw:0), but it can show other
sound cards using the -c option (-c n). If your TV card is like
mine, and has a external cable between it and the sound card, then
you are probably going to be using someting like the Line channel.

On the other hand, you probably also have controls on your TV card
as well. For me it is sound card 1, but I normally leave the
controls at max. I also have a mixer page for it in the Gnome mixer.

Both amixer and aplay are part of the ALSA package.

Mikkel
-- 

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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