[mythtv-users] Steaming HDTV Performance.
adeffs.mythtv at gmail.com
Sat Dec 23 02:09:57 UTC 2006
On 12/21/06, BRIAN LANG <brianlang75 at msn.com> wrote:
> > Date: Wed, 20 Dec 2006 21:52:30 -0800
> > To: mythtv-users at mythtv.org
> > From: bpreston at collabras.com
> > Subject: Re: [mythtv-users] Steaming HDTV Performance.
> > By definition, a full 1080i HD signal will absorb 19.2 Mbps of ethernet
> > bandwidth (actual results may vary ;). Most consumer grade Network Cards
> > Switch hardware will forward approximately 60% of bandwidth if there is
> > minimal node contention creating collisions. Depending upon the nature of
> > other traffic on your network, you should easily get two frontends to
> > operate ( I do ) on a 100 Mbps ethernet backbone.
> > If you have or plan to have network based gaming, security monitoring,
> > network cameras or home automation on the net as well, you may find
> > stressed (I do in some situations) and want to go to a 1000 Mbps backbone
> > a more creative segmented or vlan'd network design (which was my
> > Brad DerManouelian <myth at dermanouelian.com> wrote:
> > >
> > >On Dec 20, 2006, at 9:02 PM, Brad Fuller wrote:
> > >
> > >> Brad DerManouelian wrote:
> > >>> On Dec 20, 2006, at 6:50 PM, BRIAN LANG wrote:
> > >>>
> > >>>
> > >>>> I'm considering building a MythTV system. I'm a software engineer,
> > >>>> so I don't think I'd have any technical problems that I couldn't
> > >>>> figure out. I'm weighing the pros and cons of HD Tivo, WIndows
> > >>>> Vista Media Center, and MythTV. If I do build a MythTV system I'd
> > >>>> likely have a backend in the basement and two font ends. Both TVs
> > >>>> would be HD (at least eventually). My concern is the bandwidth.
> > >>>> Am I really going to be able to stream HDTV shows at a reasonable
> > >>>> rate? What kind of performance can I expect? All 3 computers would
> > >>>> be fairly decent machine and have gigabit ethernet. Thanks!
> > >>>>
> > >>>
> > >>> Lots of people use the HDHomeRun to capture 2 HDTV streams over
> > >>> 100Base-T, so it is at least able to do that. If you're going to be
> > >>> streaming more than a couple at a time, you should definitely
> > >>> consider gigabit (You should consider it anyway since the hardware is
> > >>> reasonably priced now.)
> > >>>
> > >> The capturing of ATSC is not really a cpu intensive operation using
> > >> PCI
> > >> cards (like the pcHDTV3000.) There's no encoding going on. Playing
> > >> 2 HD
> > >> streams is more intensive, but since you are going to have a
> > >> backend and
> > >> 2 frontends, you won't have much problems considering the use of
> > >> moderately new CPUs and especially if you use Nvidia video cards and
> > >> work out the XvMC kinks in your specific setup.
> > >
> > >He's asking specifically about network bandwidth. The HDHomeRun sends
> > >two simultaneous HD streams over 100BaseT.
> I'm really impressed with how helpful everyone has been. Thanks!
> The reason I asked it that currently I have two series 2 Tivos. I'm
> considering ditching the Tivo world for MythTV when I move to HDTV. When I
> transfer a recorded show over my wired network between the Tivos the
> transfer generally occurs at approximately real time (sometimes a little
> faster, so I can fast forward through commercials sometimes a little slower,
> so I have pause for the transfer to catch up). Obviously with HD I'm
> dealing with a lot more data, so my initial thought was that this would be
> very slow. Is the primary reason I can move so much more data around with
> MythTV then Tivo due to my TiVos reliance on a USB to ethernet adapter?
considering the cheap price of gigabit switch's with jumbo frame
support, it wouldn't make much sense not to use one for your Myth
setup. I also recommend the HDHomeRun solution after my experience
with multiple ATSC PCI cards. Especially now that modern motherboards
usually only have a few PCI slots, better to use those for a
PVR-150/500 or two. Also, many cableboxen these days have firewire
output which is somewhat hit or miss still, but support is better and
a lot of work is currently being done in SVN in this area. In your
case, I'd start modest. An HDHomeRun and a PVR-150/500 for standard
cable. Then go from there once you've worked the kinks out.
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