[mythtv-users] Onboard sound full-duplex ?

[Mark J. Small]

On October 13, 2004 04:27 pm, Isaac Richards wrote:
> On Wednesday 13 October 2004 03:06 pm, Maarten wrote:
> > On Wednesday 13 October 2004 20:28, Isaac Richards wrote:
> > > On Wednesday 13 October 2004 02:11 pm, Maarten wrote:
> > > > On Wednesday 13 October 2004 19:29, Tim Sailer wrote:
> > > > > On Wed, Oct 13, 2004 at 07:03:18PM +0200, Maarten wrote:
> > > > >
> > > > > Card 1 being the first capture card or the first sound card? You
> > > > > specify the audio device for playback, so you can always play out
> > > > > through the builtin device.
> > > >
> > > > With card_1 I meant the first capture card, not the first soundcard.
> > > > But I don't really think that makes any difference; you'll have two
> > > > combos of <<capture card + connected soundcard>>.  And if one of
> > > > those combos lack full-duplex, it will not be able to playback (or
> > > > -worse- it could fsck up the ongoing recording when selecting it for
> > > > playback).
> > >
> > > Why would you be using multiple soundcards for playback?
> >
> > Hm.  Okay, so maybe I'm confused, but I need a soundcard each for each
> > BT8x8 capture card, right ?  So either both those soundcards need to be
> > able to do full-duplex (otherwise live TV and playback will have no
> > sound) OR one must have the possibility within mythtv to declare one card
> > capable of recording and playback, and the other capable of _only_
> > recording. (And mythtv reacting accordingly...)  Is this assumption
> > correct so far ? Note that I'm _not_ talking about PVR250 cards, but
> > about BT8x8 cards.
>
> You're  not even close to being correct.   Why would you be using more than
> one sound card for _playback_?  Why would you think that the device used to
> playback audio is tied in any way to the device used to record audio?
>
> Isaac

Lots of confusion here,  I'll see if I can clear it up.

(1) Yes, the onboard Via sound IS full duplex.
(2) No it doesn't matter in this case

To capture the audio part of your video stream on a bt878, you don't need a 
sound card at all, you can use the bt878 sound capture hardware.  Mythtv will 
record it directly to the nuv file along with the video source.  

When you play back the recording, either using livetv or later watching a 
recorded program, you use your soundcard for the output device.  It doesn't 
matter whether the recording is live or not, the audio is still being read 
from the nuv file.

Now if you had cards without audio capture, like my Rainbow Runner G, you 
would need a sound card for each capture card.  But the bt878 can capture the 
sound for you.

Hope this helps,

Mark