[mythtv-users] Followed Digital Sound setup, many how-to's, and still completely lost.

Steven Adeff adeffs.mythtv at gmail.com
Sun Feb 4 00:09:44 UTC 2007


On 2/3/07, Rich West <Rich.West at wesmo.com> wrote:
> Rich West wrote:
> > Steven Adeff wrote:
> >> On 2/3/07, Rich West <Rich.West at wesmo.com> wrote:
> >>> Rich West wrote:
> >>>> *sigh*  I am reluctantly sending this to the listt, but no matter what I
> >>>> try, I cannot seem to get consistent results from any of the "digital
> >>>> sound" how-to's.
> >>>>
> >>>> Goal:
> >>>> Pump all sound out via SPDIF and let my receiver do the work.
> >>>>
> >>>> Near Goal:
> >>>> Hey, I would be content if I just had to switch the input on my receiver
> >>>> from the TV setting (L/R stereo in)) to my DVD setting (Optical 5.1
> >>>> Audio in).
> >>>>
> >>>> What I have tried so far:
> >>>> http://www.mythtv.org/wiki/index.php/Configuring_Digital_Sound#ALSA_Utilities,
> >>>> http://gentoo-wiki.com/HOWTO_Dolby_Digital_Out_(AC3,_SPDIF) (I have FC5,
> >>>> but I thought some of it might apply), along with following a couple of
> >>>> threads in the list.
> >>>>
> >>>> Here's where I am at:
> >>>> <..snip..>
> >>>> Although I've read the Wiki's, How-To's, and other postings, I just feel
> >>>> like I am missing something simple here...
> >>>>
> >>>>
> >>>>
> >>> Muhaha.. I just got things working.  I missed the thread from "Josh
> >>> <TwoOneSix at thatclothingco.com>" titled "Re: [mythtv-users] M-Audio
> >>> Revolution 5.1 and FC6 [Working!]".
> >>>
> >>> The piece I was missing was (sort-of) listed in his message.  I needed
> >>> to set the default audio-output to ALSA:default along with the
> >>> passthrough device to ALSA:default.
> >>>
> >>> Watching LiveTV and watching recordings now outputs via the SPDIF
> >>> optical connection (interestingly, my receiver flips to "Dolby
> >>> Prologic"), and watching DVD Video's also outputs the sound via SPDIF
> >>> optical and the receiver properly sees the incoming stream as AC3.
> >>>
> >>> Interestingly, though, MythMusic no longer outputs anything.. Gotta look
> >>> in to that.
> >>>
> >>> BYW: Thanks Josh!
> >>>
> >>> -Rich
> >>>
> >>>
> >> MythMusic has a separate device option, so you just need to go into
> >> the MythMusic settings and change it to match what you have for TV.
> >>
> > After seeing in my mythtvfrontend.log (I never even knew that there was
> > a "-v audio" option to mythfrontend. :) ):
> > 2007-02-03 13:42:04.346 Opening ALSA audio device 'spdif'.
> > 2007-02-03 13:42:04.347 in SetParameters(format=2, channels=2,
> > rate=44100, buffer_time=500000, period_time=125000)
> > 2007-02-03 13:42:04.348 AudioOutput Error: Rate doesn't match (requested
> > 44100Hz, got 48000Hz)
> >
> > And then seeing your message, I changed the output device to /dev/dsp.
> > Muhahah.. that worked.  I just set it to /dev/dsp to use the L/R audio out.
> >
> > It's actually kind of interesting that the optical input on my receiver
> > is tagged as "CD Optical Audio In".  CD's are 44.1khz, right?
> >
> > Too bad I can't pump everything through the optical connection.. I
> > wonder why it won't send it at 44.1khz..
>
> Wow.. didn't realize just how close I was. :)
>
> I updated /etc/modprobe.conf to include:
> options snd-pcm-oss adsp_map=1
>
> As per the KnoppMyth Wiki (I'm not running KnoppMyth, though), but that
> alone did not help.  However, a little further UP in that wiki entry, I
> came across an /etc/asound.conf entry:
> pcm.!default {
> type plug
> slave {
> pcm "spdif"
> rate 48000
> format S16_LE
> }
> }
>
>
> I put that in place, updated the default output device and passthrough
> device to be "ALSA:default" and set the MythMusic device back to "default".
>
> Viola!  Everything goes through the optical connection... :)

Rich, I humbly ask that you create a mythtv wiki entry for your setup
to help any of those that may be looking to use the same sound setup
you have.

-- 
Steve
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