[mythtv-users] Digital sound via optical spdif, slow after seeking

Willy Boyd willyboyd at gmail.com
Wed Oct 25 19:13:08 UTC 2006


I've been using digital sound via a USB optical spdif device (Turtle
Beach Audio Advantage Micro) for a few weeks now, and for the most
part everything works and sounds great.  I do have one remaining issue
though, and I was curious if anyone on the list has more experience
with digital spdif and Myth.

When seeking in recordings, the "previously playing" sound plays for
another second or more after the video jumps, before switching to
"next part" of the audio stream.  It's hard to explain, but imagine if
you will skipping around in commercials.  If I keeping hitting the "10
sec" skip too quickly, I'll get audio from one commercial still
playing in a different one, albeit only for a second or two then it's
back in sync perfectly.

I just assumed this had something to do with my audio receiver, like
maybe it has a buffer it needs to fill.  I've always had other optical
audio  be slow to start while the receiver displays its "Audio
Detected" message.  Well, last night, I saw something else.  I started
a torrent download of Fedora Core 6, and notice the audio fall out of
sync continually.  I had to stop & restart the recording, only for it
to fall out of sync moments later (with no skipping even).  I can't
say for certain this never happened with analog audio, but I don't
remember it (I've been using Myth for at least 2 years now).

I've tried playing with the options and didn't see a difference.
Obviously I could try a different receiver to cancel that out, but I
currently don't have anything else that plays via an optical input.
Short of that expensive experiment, does anyone else have any tips?
Options I might be overlooking?  Is it just the USB to blame, and I
need a real honest-to-goodness PCI card (like the Riviera) ?  Seems
like it should take even less processing to deal with AC-3 because
it's just passing what's already in the stream off to the output.


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