[mythtv-users] DCT-6200 w/ FireWire -- Looking for Input..

[Jarod Wilson]

On Sunday 27 March 2005 00:14, Big Wave Dave wrote:
> <--snip-->
>
> > > -I have seen that 2Ghz is recommended for an HD setup.  Is this enough
> > > for a frontend/backend combo... when capturing via firewire?
> >
> > Actually, 3GHz is recommended for an HD setup. You can get away with less
> > on a frontend-only system, but an all-in-one box needs to do more than
> > just playback, so you'd be pushing it.
>
> I don't really NEED full HD quality.  I will only be using SVIDEO
> output through an NVIDIA MX4000.
> I am just hoping to avoid the digital-->analog-->digital conversions
> by just using the firewire.
>
> Is it possible to record with firewire... but perhaps not capture at
> full HD quality?

No. Recording HD is a matter of dumping the encoded-by-the-head-end mpeg2 
stream to a file on disk. Can't resize it at recording time. You can 
transcode it to something smaller, but that's a rather time-consuming task, 
and won't do you any good for live TV.

> If so, maybe I can get away with less than 3Ghz?  It 
> seems like the price breaks are currently just bellow that.

With recent optimizations, while 3GHz is still recommended in your situation 
(combined backend/frontend) for optimal performance, its certainly possible 
you could get away with a bit less. I have a viewing-only system that is a 
mere 1.53GHz (Athlon XP 1800) and it handles 720p programming fine (though 
the cpu is pretty much pegged) and can *almost* keep up w/1080i and a deint 
filter (frequent stutter, but almost watchable). I've done quite a bit of 
work to tweak this machine to be able to get there though, its not something 
I'd recommend to anybody. Its more just a challenge for me -- I have a very 
under-utilized 2600 proc I could put in its place, but where's the fun in 
that? :-)

The odd thing with HD playback is that some folks with machines that should be 
more than powerful enough encounter playback problems (stutter, pegged cpu), 
while others (like myself) manage to get significantly slower systems 
working, so there's more to it than just raw CPU power. Choice of motherboard 
may have an impact, but I couldn't say definitively. Dunno about choice of 
kernel, I haven't had a problem with either stock FC3 kernels or 
hand-compiled ones.

A 2.8GHz P4 is probably fairly safe, and you could even have success with 2.4, 
but like I said, ymmv... Hyper-Threading seems to be a big win, you 
definitely want a P4 w/HT.

-- 
Jarod Wilson
jarod at wilsonet.com

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