Ben Bargabus wrote:

Hello again,
So as I'm planning my hardware purchases for my first system I have some
questions about how this system is intended to be used, best used, and
most commonly used (maybe all three are the same but most likely not).
The vision I have in my head based off of the reading I've done on this
list and in HOWTOs goes something like this...

dss receiver   dvd changer
   |            /
   |           /
   |          /
   |         /
   |        /
   |       /
   |      /
MythTV Backend
     |
     |
     |
  Network
     |
     |
MythTV Frontend
     |
     |
    TV


Using that system I imagine myself sitting in front of my television and
making requests to the mythtv frontend (via my remote control) that
access information on the mythtv backend.  In some cases this would be
prerecorded content but may also be live broadcast from my DirectTV
receiver or a movie from my dvd changer (I'd have a connection to the
low speed data port on each of these from the mythTV backend to control
them).  Is this possible, intended, common, best?  A second viable
option I can imagine is something like this...

dss receiver#1  dvd changer
   |            /
   |           /
   |          /
   |         /
   |        /
   |       /
   |      /
MythTV Backend
     |
     |
     |
  Network    dss receiver #2
     |        /
     |       /
MythTV Frontend
     |
     |
    TV

In this scenario the first dss receiver would be used solely for
scheduled recording whereas "live" tv viewing would be done via dss
receiver #2 (also contolled via low speed data port).  Is this more
realistic/less problematic or unnecessary because my first scenario is
fine?
Right, what you described is basically how it works. In the first diagram, you have a dedicated backend and a dedicated frontend. In the second diagram, you have a dedicated backend and a frontend/backend combo. A third diagram could have a dedicated backend and dedicated frontend, but you could put both DSS receivers on the single backend (just put an extra tuner card in the backend). (And, of course, there's the fourth diagram with a frontend/backend combo with the two DSS receivers connected directly to it--this is what I'm doing, primarily to limit the number of computers I have to keep running at all times (I currently have four with only one of them doing Myth things).)

One note, though, when it comes to your (standalone/set-top) DVD changer, you probably don't want to hook it into your Myth backend. In order to integrate it into a Myth system, you'll have to connect it to an input on a tuner card. Therefore, you would either have to have an extra tuner card (i.e. one more than the number of satellite receivers you have) or only watch DVD's when both tuners are not in use (i.e. when only recording one show or none). Also--and probably more importantly--you lose much of the benefit of DVD. All (non-high-def) tuner cards accept NTSC/PAL input. Since NTSC/PAL are interlaced formats, piping DVD output (which can be progressive--depending on your DVD and DVD player) through the tuner card would eliminate the potential for progressive playback (assuming you have a nice-enough TV that progressive is an option). Also, the MPEG-2 (lossy-format) encoded video would be decoded by your DVD changer, piped to your tuner card, encoded by your Myth box into another (lossy) format (i.e. MPEG-2 for a hardware encoder or RTJPEG or MPEG-4 for a software encoder), then decoded by your Myth box and output to the TV. Therefore, you will lose quality--even if you can't do progressive display with your TV. And, finally, there's the annoyance factor... Since Myth would treat the DVD playback as just another "LiveTV" channel, it would buffer it (to allow you to pause, rewind, etc.). Therefore, there would be a couple of seconds of delay between the time you pushed a button on your DVD remote until it "took" (i.e. when navigating DVD menus). (Note that Myth has no provisions for piping data directly to TV without a buffer, and there are no plans to add this functionality.)

Therefore, your best bet for DVD's is to a) get a DVD-ROM or DVD writer for your Myth frontend and let it play the DVD's (this is the approach I'm using, and I think the output quality--especially when using post-processing--rivals, or possibly surpasses, that of even high-end DVD players) or b) connect the DVD-changer directly to the TV and use it for direct playback (meaning you'll need a slew of remotes to work the system and you have all the input-switching rules you have to teach people when they come over.

HTH.

Mike
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