[mythtv-users] mythmusic iec958 help

Rich West Rich.West at wesmo.com
Sun Jul 6 04:34:35 UTC 2008


Joe Henley wrote:
> Gregg,
>
>  From the posts above it doesn't look like it's going too well.  I 
> continue to believe you will need to replace your sound card if you want 
> to get 44.1KHz signals into your receiver.
>
> Have you checked the SoundBlaster site (or googled) for clarification on 
> what your specific card will do?  Allen's comments above about 
> "sometimes spdif means upto 48KHz" is not 100%.  Sometimes it's 48KHz 
> only; trust me, been there, done that.  ... and paid the return shipping 
> for a limited capability card.
>
> If your Soundblaster is not designed to output 44.1KHz via spdif, no 
> tweaking of alsa parameters, etc. will help.
>
> If your particular SB model will support 44.1KHz, then remove .asoundrc 
> from /root , /home, and /etc, and anywhere else it resides.  IIRC, you 
> have already removed PukeAudio, so from there you can start using 
> alsamixer to unmute the iec958 items.
>
> The most common (from what I read on sites like this) successful MythTV 
> settings are:
> Audio output device =  ALSA: spdif
> Passthru output device = Default
> Max audio channels = stereo (The 5.1 setting is currently broken. Use 
> "stereo" and you'll still get 5.1 sound out of the system.)
> Upmix = passive
> Enable AC3 to SPDIF passthru = check
> Enable DTS to SPDIF passthru = check
> Enable internal volume controls = check
> Mixer device = default
> Mixer controls = Master
>
> What will work for you is probably very similar to this.  If this 
> doesn't work first time, then check the wiki for ways to determine good 
> alternatives to "Audio output device = ALSA: spdif".  This setting seems 
> to have several different incantations; and seems to be the one most 
> people have to change.
>
> Good luch, you _will_ eventually succeed,
For more information, check out:
http://www.mythtv.org/wiki/index.php/Configuring_Digital_Sound_with_AC3_and_SPDIF

That page will walk you through what steps to take to:
o get spdif sound working with linux (Fedora) - something you already 
have working
o get the configuration set up to work with Myth (and MythVideo) for 5.1 
and stereo output - something you already have working
o and get the configuration set up to work with MythMusic - the piece 
you are trying to get working

More than likely, you're using a system with on-board SPDIF 5.1 
surround.. if that is the case, then it should be able to be done (and 
if it is AC97 chipset based, it is definitely possible).

The key piece to get MythMusic working when you have all of the other 
components working is by setting "Max audio channels = stereo".

-Rich


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