[mythtv-users] WinTV GO Audio

[Joseph A. Caputo]

On Wednesday 10 March 2004 14:00, Matthew Carlin wrote:
> Hi,
>
> I just completed a working MythTV install off of Red Hat 9 using
> Jarod's guide.  I have onboard sound but I'm using a soundblaster PCI
> which works just fine. I had an ATI TV Wonder card, but it performed
> poorly (and, as I have since figured out, it doesn't work with
> btaudio), so I gave it up, and bought a Hauppauge Win TV Go. The
> video is working nicely, but of course, now I find that it doesn't
> work with btaudio either.
>
> I found this from searching the archives:
> >Hauppauge WinTV Go. Video capture works with older versions of this
> > card, which use a bt878-compatible chip; newer versions use a
> > different chip (CX21881) that is not yet supported by V4L (a driver
> > is under development; watch http//bytesex.org/cx88/ for news).
> > Audio requires using a jumper to a sound card; btaudio does NOT
> > work.
>
> Ok, so, does that mean I can still get audio working on the card (ie,
> do I save a return trip to Fry's to exchange the sucker)? If so, can
> someone point me to information about how to do so? I searched the
> list for posts about using a jumper for the card, but I couldn't find
> any.
>
> One more question/suggestion: Did I miss a warning somewhere about
> some bt based V4L cards not working with btaudio? If not, could
> someone put such a warning on the mythtv site, or in one of the
> guides? (I only found it out incidentally, after several days of
> reading the archives to solve other problems)

btaudio is not necessary to use v4l/bt878 cards; it's merely convenient.  
In fact, I don't believe there is even a btaudio-like driver for 
Windows; there you have no choice but to use an audio patch cable.

What you *do* need for a bt878-based card is an audio recording device 
(either btaudio or sound card line-in) and an audio output device 
(sound card output).  If your card doesn't support btaudio, then you 
just patch the line-out of your tv-card to the line-in of your sound 
card.

There are 2 common problems most people have with sound configuration & 
MythTV.  The first is that in order to use a single sound card in a 
combined frontend/backend system with a V4L (not hardware encoder) 
card, your sound card needs to support (in hardware) "full 
duplex" (meaning the ability to simultaneously record one thing and 
play something else).  Also, even if the card supports full duplex, the 
driver for the card (ALSA or OSS) may not, so it's a bit of a crap 
shoot if you're stuck with onboard sound.  If your sound card won't do 
full duplex, you have the option of using 2 separate sound cards (1 for 
recording from the TV card, and one for playback).

btaudio simplifies the whole sound issue, since it gives you a dsp 
device to record from the TV card right off of the PCI bus, thus 
eliminating any connections between recording in Myth and your sound 
card; you can then use any old sound card & driver for playback.

Don't go ditching perfectly good cards just because they don't support 
btaudio; lots of folks on this list use the TV Wonder or WinTV GO with 
great success.

Oh, and by the way, all this is covered in the docs.  Please read them 
thoroughly.

-JAC