[mythtv-users] surround sound.

Willy Boyd willyboyd at gmail.com
Thu Nov 16 00:21:00 UTC 2006

I finally tracked down an adequate test file
(http://pessoal.onda.com.br/rjamorim/stuff/test.dts.zip), and played
it with this call:

("turtle" is the alias I gave my Turtle Beach USB card, as I have an
SB in there as well)
$ mplayer -ao alsa:device=turtle -ac hwdts test.dts

DTS encoded file, played with passthrough.  I got "Left Front", "Right
Front", and so on, discretely on each speaker.  In other words,
confirmation that this little doohickey *does* digital passthrough on
the optical-outl.

- Willy

On 11/14/06, Willy Boyd <willyboyd at gmail.com> wrote:
> I'm pretty sure the "virtual" is talking about the extra fancy
> processing that's done on the 2-channel analog sound that comes out
> the headphone jack, to make that sound more immersive.  However the
> device comes with a mini TOSLINK adapter, and as I understood it,
> outputs digital audio straight from the data stream when using Optical
> out.
> If that IS the case that the little mini USB dongle is actually
> encoding AC3 digital audio, I really appreciate the discovery and it
> gives me the info I need to take back the Micro and get a Riviera.
> FWIW though, this is what I've experienced:
> - I had to enable "AC3 Passthrough" in Myth to get digital audio.
> Doesn't this instruct Myth to not decode the AC3 data to WAV but
> instead dump the data straight to the soundcard?
> - Using the AC3 passthrough option with MPlayer, allowed me to play
> 5.1 audio out my speakers.
> - I'm pretty sure the notes I found on the ALSA driver change that
> enabled this (too busy at work ATM to find the link), said something
> along the lines of digital passthrough
> - Isn't analog->"virtual surround" called ProLogic, and really
> 3-channel?  When watching DVDs, I definitely get discrete sounds out
> of my back surround speakers and center channel, and my receiver
> definitely think it's getting 5.1 Dolby Digital surround.  Again this
> would mean the USB device is actually a DD5.1 encoder, which I guess
> is definitely possible.
> - I *did* have trouble finding a really "sample" file that I could
> guarantee was a good test of 5.1 channels, so I used my copy of The
> Matrix.  If anyone has a link to a sample file I could play with
> MPlayer's AC3 passthrough (something that does discrete, sequential
> sounds on all 5 speakers), I'll do that test tonight.
> On 11/14/06, Rich West <Rich.West at wesmo.com> wrote:
> > David Rees wrote:
> > > On 11/5/06, Willy Boyd <willyboyd at gmail.com> wrote:
> > >
> > >> I'm really impressed with Turtle Beach.  For what it's worth, they
> > >> also make the "Audio Advantage Micro", which is a USB stick about the
> > >> size of a thumb drive, that has a full TOSLINK (Optical) output.  For
> > >> the same price, obviously the Riviera is a much more complete and
> > >> solid solution, but for those strapped for PCI slots, the USB is about
> > >> as good as having onboard.  Worked outta the box for me on FC4 with
> > >> nearly no setup (just changing MythTV settings, no driver business).
> > >>
> > >
> > > Ooh, that is tempting, only $23.99 + tax/shipping on NewEgg, same
> > > price as the OEM version of the Riviera but doesn't use a PCI slot
> > > which I've stuffed with tuners... Anyone try both and notice any sound
> > > quality difference?
> >
> > Hrmm.. that one is listed as "Virtual" 5.1 Surround Sound where as the
> > Zalman ($59!) on NewEgg is listed as "5.1 Surround Sound" (no mention of
> > "virtual").  From the docs, it seems like the Turtle Beach one is taking
> > analog audio and converting it to 5.1...
> >
> > -Rich
> >
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