[mythtv-users] 32khz AC3 Streams was: Sound problem with AC3 passthrough

Rob Baumstark rbaumstark at gmail.com
Wed Jun 7 02:08:03 UTC 2006


> Rob, just started testing your clip only to find that my alsa is having
> issues I haven't even pinned down yet (iec958 and spdif devices not
> recognized ??? yet mplayer and myth pass perfect 48k with ALSA:default
> and my .asoundrc). Rather than hijack your thread, I'll go on about
> fixing my stuff.
>
> However, your clip is playing back fine here with the device=default so
> here is a copy of my .asoundrc
>
> "Couldn't find matching filter/ao format!" looks intereting though. I
> did try removing liba52 from my system to see if that was the culprit
> but myth, mplayer and alsa keep playing the clip (and some of mine) just
> fine.
>
> Following is my .asoundrc (earlier Mike Dean version). HTH
>
> --
> mw

Just let me confirm this, this statement confuses me a little,
"mplayer and myth pass perfect 48k with ALSA:default"

Now for the sound to play back properly, there are really only a few
things that could be occuring.
1. your hardware is capable of passthrough of a 32khz AC3
2. your hardware/software is decoding 32khz AC3 -> PCM, resampling,
and out-putting PCM.
3. your hardware/software is decoding 32khz AC3, resampling, and
re-encoding into AC3 to output at 48khz.

What I posted up there can't be turned into 48khz anything without
decoding the AC3 (well - anything except chipmunk-mode, which is what
I get).  I'm  curious as to what your receiver is indicating while you
say that its working.

(gmail acting funny - sorry if this sends twice)


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