[mythtv-users] Audio - PCM, Master

Michael T. Dean mtdean at thirdcontact.com
Sat Mar 4 03:32:52 UTC 2006

On 03/03/2006 08:01 PM, R wrote:
> In MthTV we have:
> MythTV->Main->Utilities->Setup->General->Audio->Mixer Controls-> PCM or Master
> In Fedora Core 4 we have:
> KMenu->Sound & Video-KMix->Current Mixer->Input->PCM
> Pardon my ignorance.
> What is PCM?

In short, it's similar to what Windows calls "Wave" (or "Wav"?).  
Technically, it's Pulse-Code Modulation

> What is the difference between PCM and Master?

Master typically controls the volume across multiple controls (including 
CD and PCM and ...).  However, note that on some sound cards, it does 
*not* affect surround volumes (i.e. Center, Surround, LFE).

If you can't tell a difference in functionality on your system, it 
doesn't matter which you use.  However, it's often nice to make sure you 
set Myth to use the same controls used by other applications (like xine 
or MPlayer) otherwise, you'll end up adjusting Master in one then PCM in 
others, so where you leave one and enter another determines the maximum 
volume range you have available...  (I.e. don't let apps "fight" each 
other or you'll constantly be using external programs, like alsamixer, 
to "reset" your volumes.)


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