[mythtv-users] Specs

Brad Allen Ulmo-Myth-Users at UseNet.Q.Net
Fri Jan 9 01:54:05 EST 2004


> > My plan is to try and get it to act much like dumb terminal - basically
> > just a display device, X, Myth and everything else running on the
> > server.

> So, you plan to have your server/backend decode the HD stream for
> playback and pipe raw video to your X-box, which will output it to
> the TV?  I hope you have a lot of bandwidth on your LAN...

This is something I want to do even with simple decoding tasks like
displaying something on my '350 (which has its own decoder); right
now, I get skips whenever OSD comes up, which may be some driver
issue, but I know there's also CPU being used, and I wish it could
just send the hard CPU stuff over to my backend server to crunch out
and send back to my slower 550MHz box with the '350 in it.  My network
seems fast enough: the little PCI GbE card in my 550MHz PIII box is
quite swift and unobtrusive CPU-wise, and I'm running MTU 9000 with
NFSv3 set to blocksize 8192 no problem!

> ...or do you plan to run mythfrontend on your server/backend box,
> and export the X display to your X-box?  That will work for the GUI,
> but I don't think you'll be able to watch video that way.

I originally thought this might be possible.  What we need for this is
an API for X servers and clients that allows their clients to do
whatever they have to in order to use the remote end.  Come to think
of it, that's nothing: X has everything it needs to continue to
ivtv-fb Xserver itself out to the '350 as now, and then all we need is
a little plugin module that transports all the correct IO and ioctl's
between the '350's box and Myth backend server.

There are a few kernel projects for network block devices in Linux; is
there also a virtual network character device driver too?  Has anybody
tried it with the '350?  I might REALLY want to use that.  That would
by far and away be a great reason to try Linux 2.6 again (I got it to
mostly work, but I'm retreating in a bit of stability and
supportedness right now while I try to get to second base with
everything.).

> MythTV wasn't designed to work that way.

Bah humbug --- why not and who said so and so on and we'll do it
anyway perhaps, but thank you for confirming the same conclusion I
sort of came to myself for now.

> The frontend (i.e., the box hooked up to your TV) has to do the
> decoding.

So I've noticed.  Not a good combo for my setup.

> In your 
[not mine]
> case, if you want an X-box frontend, then you're going to be trying
> to get an X-box to decode the HD stream.
> 
> Your best option here would be to have the backend auto-transcode
> your recordings down to a resoluton that can be handled by the X-box
> for playback.  Of course, there are 2 drawbacks to this: (1) you
> won't be able to watch your recordings until after they've been
> transcoded, and (2) it seems kind of pointless to record an HD
> stream and then transcode it down to NTSC/PAL resolution.
> 
> -JAC

I remain silent on this issue of XBOX.  However, I'd like to see more
network transparentness in all that has to do with Myth and the
systems it uses.

Ideally, I'd like to be able to run at capabilities that could
seriously consider comfortably using full-tilt uncompressed HD
DVI-like stream over my GbE, and just have the target host buffer it
for nicely metronomed DVI output, and whatever local interactive stuff
it needs to do (LIRC, keyboard, mouse, heat the room with noisy fans
(or not, actually, which is the whole point of a remote noisy backend
and local quiet low-resource display frontend), etc.)

Meanwhile, I'll be happy to just get the backend processing more of my
'350 output streams which seem to be choking mythfrontend on my 550MHz
PIII Dell Optiplex GX1.  (It could just be the IVTV drivers, though.)

It would make a LOT of sense to have backend process streams that need
ANY transcoding in my setup, even for smoothing out the MPEG, cutting
commercials, conforming audio coding to what the '350 needs to output
(e.g., my ATSC in streams, which do not just "dd" to my '350),
changing aspect ratio if necessary (HD), etc.

I'm forgetting something here.  My DVD is in my backend server.  I
want to watch it over the network.  Is DVD already in MPEG2 '350
outputable stream?  Anyway, whatever transcoding it needs, I certainly
don't want to bother my PIII with; it already has to be my router,
mail server, DNS, etc., and it's low on memory AND disk space.

That's one of my zillions of little projects: get DVD to go over
network to my '350 out.  Ideas?  That's not a topic for this mailing
list until we want Myth to do it, right?  Will Myth do it?  (Now I'm
showing my ignorance in bounds.)


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