[mythtv-users] Watch TV sends audio to PVR-350 audio-out, but recordings don't---any clues?

[f-myth-users at media.mit.edu]

[Please keep me CC'ed or I probably won't see replies in a timely
fashion!  And if this is more appropriate for the -dev list, please
either forward or tell me and I'll forward.  Tnx.]

I've been installing a two-machine MythTV setup based on KnoppMyth
R5A22, and I've been running into problems that the people on the
forums there don't seem to have heard of; I'm hoping that people here
have, and can help.

The setup:

My current setup has a master backend machine with several Hauppage
PVR-250's in it, and secondary backend that I'm also using as a
frontend, because it has a single PVR-350 in it; that's the machine
that I'd like to use to watch video from.  (I haven't yet configured
the 350 as a capture card, so I'm only using it as an output channel
right now.  See the PS.)  Both machines are identical Athlons running
whatever comes by default on the KnoppMyth R5A22 ISO, and started from
blank disks.

The machines were set up as MBE/FBE using the instructions at [1], and
the 350 was configured using the script at [2].  (Note also that [2]
installs a new version of ivtv, in case that matters; I -suspect that
it installed something from 0.4.0 but I'm not sure and am not sure how
to positively identify the version number I'm using; if anyone thinks
this is an ivtv problem and that this matters, can you advise on how
to check?  Tnx.  [And if it did install a new ivtv, it did so only
on the SBE/FE (1x350) machine, not on the MBE (Nx250) machine, because
I ran the script on the SBE only.])

Both [1] and [2] ran into snags having to do with the database.  For
the MBE/FBE setup in general, it's theorized that recent mythfrontend
builds have a bug in how they initialize the database such that the UI
works but Watch TV breaks; see the last page of the long thread at [3]
detailing how I got screwed by this and was eventually able to fix it
(with a workaround which is not clear to me is correct, but seems to
work---expert opinions appreciated).  For the 350 setup, the script
was never tested in a two-machine setup (its author has only a
single-machine configuration), and I had to go in and actually make
the database edit manually that it was trying to do; see [4] for that.

The problem:

I'm currently in the situation where, if I select Watch TV, I get
audio and video from the 350's outputs just fine.  These are coming
from one of the 250's on the backend machine, which is trivially
provable by (a) the fact that the 350 isn't configured yet as a
capture card, and (b) the fact that the 350's RF-in isn't even
connected.  So clearly frontend/backend communication is working..
(Not to mention that I'm using an IR receiver plugged into the 350's
remote-in.)

But if I record a show and then try to play it back, I get video just
fine from the 350, but no audio anywhere (not on the card, and not
from either motherboard soundcard output).  This smells to me like
some sort of database misconfiguration somewhere (perhaps only
because I got screwed twice by such things), but for all I know is
something completely different.  I just don't have a clue where to
look or how to even debug the situation; I'm finding detailed
documentation about the innards rather scarce on the ground and would
appreciate ideas about where to even look (short of "pull all the
source and read it").

The only other thing I can think of to try would be to put a spare
disk in the SBE (the one with the 350) and do a single-machine install
onto it, then run the 350 TVout script, and see if recorded audio
works -at all- to a 350 in the R5A22 KnoppMyth distribution even in a
single-machine configuration; if it does, I could at least dump the
database and compare every setting in it to the database I've
currently got.  That's a few hours of work, and I'm not even sure this
is a database problem in the first place, so I'm reluctant to do this
unless no one else has ever seen this problem before (which seems
unlikely).

I'm not even sure how to figure out if audio was even -recorded- in
the recorded video, although I'd be a bit surprised if it wasn't,
since it seems that playing live TV using (presumably) the same card's
tuner works just fine.

Can anyone help or lend some suggestions?  Has anyone seen this
behavior before?

Thanks!

[1] http://mysettopbox.tv/linhes.html
[2] http://mysettopbox.tv/phpBB2/viewtopic.php?t=3886
[3] http://mysettopbox.tv/phpBB2/viewtopic.php?t=6618
[4] http://mysettopbox.tv/phpBB2/viewtopic.php?t=6683

P.S.  I have yet to find a clear explanation of one configuration
detail:  In a two-machine setup of the type I have, which machine
should I configure the 350 on if I'd like to make it a capture card?
Should I run mythtv-setup on the SBE (aka the FE, aka the machine that
has the 350 physically installed in it)?  That's my guess, since
otherwise it's completely unclear to me how mythtv-setup knows which
card is installed in which machine (especially if there are, say, -3-
machines...), but on the other hand, both the machines are talking to
a single master backend that's on one of them (currently the one with
the 250's in it), so perhaps it's the backend where this needs to be
run.  The actual architecture of which machine stores what is fairly
unclear to me, since I'm not sure where other bits of state are being
held that might not be in the SQL database on the backend---or what
almost all of the various entries in that database are supposed to
mean, for that matter.