[MPlayer-dvb] DVB Audio connectivity [was:] DVB Playback Issues

[Bill Pringlemeir]

[sorry about gmail's stupid formatting issues]

On 20 Dec 2011, divey at versatile.com wrote:

> I'm actually not sure if my screens accept AC3 input. I tried two
> different screens… an Elo 4200L
> (http://www.elotouch.com/products/ids/4200L/default.asp) and a Dynex
> DX-24E150A11. I did not find any mention of AC3 for either of them and
> the audio settings don't reveal any useful information.

There are a couple of ways you can connect audio.  It sounds like you
want to use the speakers attach to your monitor.

 PC   video card    <-- HDMI -->               Monitor
      audio card    <-- TRS -->

The 2nd way needs an audio card hooked to the video card,

 PC   video card    <-- HDMI -->               Monitor
      ^
      internal cable
      v
      audio card

http://en.wikipedia.org/wiki/TRS_connector
http://en.wikipedia.org/wiki/Hdmi
http://en.wikipedia.org/wiki/Spdif

Hdmi supports both audio and video in a single cable.  The previous
generation of audio and video cabling was DVI and 'spdif'.  The 'spdif'
connectors were either coax or fiber optic (probably multi-mode).
Because of bandwidth considerations, the only way to send 5.1 sound over
spdif was to encode the signal (like mp3).  This encoding is called AC3.
The HDMI audio is suppose to support all of the SPDIF, plus more.
However, I believe that your monitors may not support HDMI sound.  The
ATSC (North American TV) uses an 'AC3' encoding.  So, spdif, AC3 and
HDMI sound are sometimes used loosely to mean the same things.

You need to have alsa setup to play these different connectivities
before mplayer can begin to use it.  So do you have the 'TRS' connector
plugged in or are you just using an HDMI cable and getting sound?  How
are games, error beeps, etc playing.  You may have 'speaker-test'
installed with alsa-utils.  You can use this to see if a cable is needed
or not.  Ie, you might have the both cables to the monitor, but actually
only be using HDMI.

All this said, the stream you uploaded seems very messed up to me.  I
would try something from 'dvb-apps' or something non-mplayer to grab a
stream.  Also, from about 2.6.31-2.6.36, there was some re-organizing of
the Linux DVB drivers.  It made the code more sensible, but there are
lots of changed to the TV capture cards during these releases.

Hth,
Bill Pringlemeir.