[mythtv-users] Audio - PCM, Master

Brian Wood beww at beww.org
Sat Mar 4 01:13:09 UTC 2006

On Mar 3, 2006, at 6:01 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?
> What is the difference between PCM and Master?
> Given that my MythTV box:
> 1.  Runs both frontend and backend.
> 2.  Has 1 TV Tuner card.
> 3.  Has 1 sound card.
> When should I use PCM?
> When should I use Master?

Your system has a sound mixer. "Master" controls the output of the  
(virtual) mix bus. "PCM" is an input to that mixer, controlling it  
controls only the level of that input going to the mix bus.

Both will control the ultimate output level, and if the PCM input is  
the only one you are using (common for a MythTV system) then it  
really doesn't matter which one you use, although you probably don't  
want to run either one too high if you can avoid it.

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