[mythtv-users] SA4200HD via 1394, mixed SD and HD

[Mark Staudinger]

This is just an informational post detailing some of the small problems
I've had with using a SA4200HD STB with a firewire connection with MythTV,
as well as the resolutions.

I got the STB shortly before SA4200 support was added to MythTV SVN, and
by the time I got my cables all sorted out it was working.  Initially I
had some stability problems:  every week or so, a firewire recording would
fail, and I would have to power-cycle the STB as well as re-start the
backend to get things working again.

This was all taken care of after enabling BusReset in
"libs/libmythtv/linuxfirewiredevice.cpp" (back when this was not enabled
by default), and in subsequent SVNs this has been very reliable without
changes.  Thanks to whomever fixed that!

I have two remaining problems.  The first, I don't know how to debug: 
I've only run into it twice.  The backend claims to have recorded a show,
yet the file simply does not exist.  There were no unusual messages in the
mythbackend log, just notations that the recording was started & stopped
at the expected times.  I've recently upgraded to SVN r16382, and will
post again if I ever see this specific behavior.

The other problem is a bit peculiar to my setup - I have a combo FE/BE
that is only capable of Standard Def. output.  My two recording sources
are a PVR-250 and the STB via firewire.  Until I get an HDTV and upgrade
my frontend, I am using "mencoder" to halve the horizontal and vertical
resolution of the HD recording.  This gives me a file that I can watch on
my SDTV (and it looks better than watching broadcast, with no overscan),
as well as archive to DVD.

On the SA4200HD, no matter how fast you enter the channel numbers, channel
changes are slow.  This is due to the box itself, not MythtTV.  What can
be a problem is the fact that MythtTV begins streaming before the channel
change finishes.

What I wind up with then is a file that has a brief section of HD
material, followed by the SD stream that I'm trying to record.  Since I
cannot display HD material, I get a "Failed to Reinit Video" message and
cannot watch that program.

Occasionally I get "lucky" and will be able to sneak a "fast forward"
command in before MythTV finishes the screen init, and I can then watch
the SD programming, but without sound.  I'm apparently skipping past
something in the stream that is required to detect or set up the audio
tracks.

What I've settled on is this change to
"libs/libmythtv/firewiredevice.cpp":

in function FirewireDevice::SetChannel, ~line 222, I added a 3 second
sleep after the channel change, just before the function returns.

It may be that a shorter sleep duration would work.

Hopefully this info will be useful to the 5 other people who have a
similar setup :)

Cheers,
-=Mark