[mythtv-users] A noob question regarding hardware req. and hardwarecodecs

[Joseph A. Caputo]

Comments inline.


> -----Original Message-----
> From: mythtv-users-bounces at mythtv.org
> [mailto:mythtv-users-bounces at mythtv.org]On Behalf Of John Wells
> Sent: Tuesday, August 05, 2003 12:32 PM
> To: mythtv-users at mythtv.org
> Subject: [mythtv-users] A noob question regarding hardware req. and
> hardwarecodecs
>
>
> Hi guys.  New to the list and MythTV and have a few questions, if you
> don't mind.
>
> Here's what I'd like to do with my Freevo or MythTV PVR:
>
> R.1 - Watch live tv while recording another show on another channel
> R.2 - Watch live tv while recording the currently viewed show.
> R.3 - Pause live tv.
>
> Here's what I have regarding hardware so far:
> - ATI Tv-wonder tuner card (w/stereo)
> - Geforce 2 with S-video out
> - 256 mb ram
> - 40 gb harddrive
> - CD-RW
>
> Now here's where I'm a little unsure of what to get next.  I have a AMD
> Athlon XP 2200+ I can throw at this baby, but I'd hate to use my big mean
> system for a PVR if I don't have to.  My other option is to buy a system
> from e-bay, but my $$$ range dictates (based on current prices out there)
> that the fastest I'll be able to buy will probably be around a PIII-500
> (give or take a 100) Mhz.
>
> Now the questions:
>
> 1.  Will a 500 Mhz CPU suffice for what I'd like to do, or will I really
> have to go with the 2200?  I'd like at least regular TV quality video (but
> truthfully, it'll probably bug me if I don't have the best ;-))

Probably not with your current hardware.  Possibly with a hardware encoder
(see below).
General rule of thumb: ~1GHz per encoding stream, + at ~500MHz for playback.
I've got an Athlon XP 1600+ handling a single V4L tuner, which is just about
enough power.  It'd be nice to have a little more breathing room, though.  I
definitely couldn't handle 2 V4L tuners without *really* sacrificing
quality.

> 2.  If I buy a hardware encoder like the Haupauge 250 or 350, what sort of
> effect will that have on CPU requirements?  Assuming a purchase of one of
> those cards, what CPU could I get buy with?

A hardware MPEG encoder reduces the encoding load on your processor to
virtually nothing.  Thus, with such a setup you really only need a system
that can handle full screen MPEG-2 decoding & playback.  A PIII-500 might be
OK there.

> 3.  Do I have to buy a second tuner card to be able to record one channel
> while watching live tv on another (See R.1 above)?

Yes.


> 4.  Can a MythTV system be used for other things (i.e., can I drop out to
> an X session), or does the software pretty much need a dedicated machine?

The frontend (user interface) is separate from the backend (interface to the
tuner card, scheduler, etc), so it's quite possible to quit the frontend and
use your machine for other things.  Keep in mind that if your system doesn't
have a lot of spare CPU, doing things like compiling while the backend is
recording something could cause dropped frames/stuttering recordings.  The
backend needs always to be running if you want to record scheduled programs.


> 5.  Is there any way to get MythTV to communicate with my Comcast digital
> cable box so that I can take advantage of the extra channels?

Depending on the model of your cable box, you can control it with either a
serial cable or an IR transmitter.  Search the list archives for specifics.


-JAC