[mythtv-users] DirecTV Notes

Rod Roark rod at sunsetsystems.com
Thu Aug 16 06:02:18 UTC 2007


Just wanted to share my recent experiences, frustrations and solutions regarding
MythTV with DirecTV, as that may help some folks.  This was also posted to the
KnoppMyth "tips" forum.

My hardware for this is an old homebrew machine with a mini-ATX AOpen MX34
mainboard, P-III 933 CPU, 512MB PC133 SDRAM, 250GB WD IDE hard drive, Nvidia
MX400 video, cheap 100 Mbps ethernet card, AOpen mini-tower case, Pioneer
DVR-112D DVD-RW, and a brand-new Hauppauge PVR-350.  This is for SDTV only.

I installed KnoppMyth R5F1, initially with no listings grabber as I was
anticipating creating my own, and didn't have a solution yet for changing
channels on my RCA DRD435RH satellite receiver.  I put in one dummy channel for
testing purposes.

Since I had no channel changing solution yet, I needed to give Myth a
channel-changing executable that will make it happy while doing nothing. 
Putting my vast programming skills to work, I accomplished the task with this
shell script which I installed as /usr/local/bin/changedummy:

#!/bin/bash
exit 0

My first problem was a black screen when going to watch TV.  To make a long and
anguish-filled story short, there were two things causing this:

1. xorg.conf specified /dev/fb1 in the [Device] section, and this needed to be
/dev/fb0.

2. I needed to add "options ivtv-fb osd_compat=1" to /etc/mythtv/modules/ivtv.

It seems to me these could and should be handled by the installer.  I can't
imagine how the typical prospective KnoppMyth user could be expected to figure
them out.

Next problem: crappy video quality.  Flashing, pixelation, snow, green faces. 
It turns out that when you send composite video to the S-video input of the
PVR-350 using the adapter provided with the card, you need to specify "Composite
1" as the capture type and not "S-Video 1". The adapter is not really capable of
generating a proper S-Video signal.  I can see that someone with less patience
than I might have just concluded that video quality sucks with this card (or
with MythTV), and moved on to another solution.  I almost did that.

Next, I signed up for an account at labs.zap2it.com (soon to go away), grabbed
listings and ran mythfilldatabase.  So far so good... I could watch TV, look at
the schedules and do manual recording.  Most importantly, my wife liked what she
was seeing.  The weather plugin was a big hit also.

Now I was feeling more confident that MythTV would work for me.  It was time to
move on to a proper channel changing solution.  For that, I made a cable as
described at dtvcontrol.com, and tried running /usr/local/bin/d10control.pl with
various arguments from the command line (accessed via ssh from another machine).

Alas, it didn't work.  Tried reversing the cable connections, still no luck.  I
called DirecTV support and finally talked with a technician who was reluctant to
say anything beyond "the low speed data port is just for diagnostics".  I told
him, "look I already have documentation for this thing and know that it supports
commands to change channels; I don't need your help in doing that, I just need
to know if the feature has been disabled so I don't waste my time trying to make
it work."  So he put me on hold for a while to check, and finally came back and
said that it appears to be disabled.  I believed him.

Fortunately, I still had in another room an old Sony SAT-B2 from about 1997 when
I first started using DirecTV.  Did a bit of googling, made a serial cable for
it, found a "sony.pl" script for changing channels (why doesn't KnoppMyth
include this?) and tried it all out.  Success!

My next project will be coding a DirecTV grabber.  More on that later.


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