[mythtv-users] Static noise from AC3 passthrough

[Gabe Rubin]

On 6/6/06, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> On 06/06/2006 03:00 AM, Gabe Rubin wrote:
>

> Probably a small typo in your ALSA config file (assuming you mean you've
> specified that "digital" should be the default by uncommenting the line
> that slaves default to "digital-hw" -- which it sounds like is what you
> mean.  Only reason I'm being picky with the terminology is because if
> you have actually set "digital-hw" as the default, you would get the
> same as below.  Perhaps you forgot to uncomment the line "type plug"?
I will double check my ALSA config file (~/.asoundrc correct?).



>
> Hmmm.  I think I'll modify the config to make it easier to understand
> (once I return home this weekend).  Thanks for asking the question,
> though.  Always glad to find ways to improve.

Always glad to have others make things easier for folks like me.  The
thanks should be going the other way!

> >, instead I need to do
> >'aplay -d digital-hw Track01.wav'.  It sounds like what others have
> >described as not resampling properly
> >
> >
>
> That's exactly what using "digital-hw" should do--send the data through
> directly to the hardware without resampling.
>
> Use "aplay -d digital Track01.wav" for proper playback.

My writing was confusing.  When I enter 'aplay -d digital-hw
Track01.wav'. I get the proper sound that is dts encoded and my
receiver shows dts.  When I enter 'aplay  Track01.wav' I get static.

>
> The new comments I added to the ALSA conf file explain that you should
> never use "digital-hw" or "analog-hw" directly--they are for "internal
> use only".

So what am I supposed to do?  Use aplay Track01.wav to test, and make
sure that it alsa is using digital-hw as the proper default?

>
> >Seems like that may be the first step I need to tackle -- an improper
> >.asoundrc perhaps?
> >
>
> Quite possibly.  My recommendation is to start over with the config file
> in the wiki (

I tried using this and got screwed up.  I think I had set something up
in my .asoundrc and can't see what the difference between the two is.
I will inspect the two files to see where the differences are at some
point.

> http://mythtv.org/wiki/index.php/DigitalSoundHowTo#Setting_up_ALSA.27s_.asoundrc.2C_Properly
> --you'll get more descriptive comments than the old version had, so it's
> definitely worthwhile if using an older version), changing the device
> for "digital-hw" (probably the only necessary change) and modifying the
> default as desired.  The config file now starts with "mixed-analog" as
> the default, so changing default only requires commenting that line and
> uncommenting the appropriate other line.

This is what I thought I had done, but obviously I took a step to make
my last .asoundrc work that I didnt with this.  And by work, I mean it
plays, but it does not send the dts encoded files through in a format
that my receiver plays properly.

Thanks for all your help on this and the other projects of myth!