[mythtv-users] AC3 and/or S/PDIF (again)

[Jarod Wilson]

On Friday 20 January 2006 05:11, William Lewis wrote:
> >Do you have volume control via myth with this method?
> >
> >I can get all my audio output through the spdif connector, but can
> >not find anyway of controlling the volume via myth (this would be my
> >preferred option as I like the on screen volume display).
> >
> >My amp is in a different room (as is the myth box for that matter).
> >So I would not have any visual indication of mute or volume level if
> >I don't do it via the on screen display.
>
> No, Ben, I don't.  And, as I understand it, this is impossible.  Since
> we're just passing through a digital signal to the receiver, it's all up to
> the receiver to deal with it.  In order to change the volume, we would need
> to decode the audio, sample down the volume, reencode it, then pass it on
> to the receiver.  Maybe it's possible, but it certainly is not very
> efficient. And, by the way, this is all just speculation.  I don't really
> know how it works, but my explanation made sense to me.

And your explanation is more or less correct. If you're passing raw digital 
audio, its completely raw, you can't controll its volume level. Might be best 
to let Myth do the audio decoding and pass PCM audio instead of raw digital 
audio. Could also try to rig up something with an irblaster if you're dead 
set on having the amp in a different room and passing raw audio.

-- 
Jarod Wilson
jarod at wilsonet.com
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