[mythtv-users] re: DRAFT of proposed new FAQ (or HowTo section)

Bruce Markey bjm at lvcm.com
Wed Jun 25 13:56:14 EDT 2003


Joseph A. Caputo wrote:
...
> I assume you're using an external digital cable or similar box, and running
> the audio straight from there to your sound card, then?  If you're using the
> 'tuner' aspect of the VE rather than the 'video-in', then you're only
> getting whatever sound the VE supports.

I never really bought into this mono vs stereo thing. The
TV audio analog signal includes whatever the station is
broadcasting. Some stations/shows have two channel stereo.
Some station/channels use Dolby ProLogic to encode surround
information into the two audio tracks.

If you use the patch cord from the audio out of the capture
card to line-in of a soundcard, the audio out seems to be
a simple analog connection over a stereo mini phono jack.
I've never seem a card come with a mono phono jack patch
cable. The soundcard then digitizes the audio tracks. If
you're soundcard/receiver/speakers handle ProLogic, you
get surround sound.

Now, some *boxes* may say that the card has dbx-stereo. This
is because they have a stereo DSP chip on the card. If you
can get btaudio to work, it would record stereo including
the surround encoding. Boxes for cards that don't include
a DSP are not marked as stereo (and are therefore preceived
as being mono?).

I've never paid $90-$100 to get a capture card with a DSP
that only works at a fixed sample rate and that I can't
upgrade if I don't like the sound. Instead, I've bought a
variety of $30 (mono ;-) cards from AVerMedia and Hauppauge
all of which have a stereo mini phono jack patch and all of
them seem to pass through both tracks just fine to allow
record and playback of stereo and surround sound.

However, if there are any cards that put a mono signal over
both lines on the patch cord, that would be worth knowing.

--  bjm





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