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2003 Dec 09 01:49

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Re: [vox] Tivo question
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Re: [vox] Tivo question



> On Monday 08 December 2003 09:17 pm, Rob Rogers wrote:
>> > Take this one, for example:
>> > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2770648713
>> >
>> > In order to make it a total multimedia station, just add a TV tuner
>> ($50
>> > - $75), IDE DVD/CD RW combo drive ($50), and a video card with TV out
>> > ($50), and you're all set. If you have a wireless network that you
>> want
>> > to connect to, then you can add that card for < $50. (I just looked up
>> > these prices on newegg.com. Refurbished hardware would be less.)
>>
>> From my experience (and that of many others on the MythTV mailing lists
>> and chat) that box will be unuseable with a standard TV Tuner. I've got
>> a
>> standard Hauppauge bttv card, and my 1.4 GHz (not a 1400, and actual
>> 1.4GHz) could record and play a single stream (or watch TV "live") with
>> the processer at 80-95% capacity.
>
> That's odd. I've used a FuturePower all-in-one computer that had 800Mhz,
> 128
> MB RAM, and an included Prolink TV tuner that Linux supported -
> http://www.newegg.com/app/ViewProductDesc.asp?description=14-108-108&catalog=47&manufactory=BROWSE&depa=0

That reminds me, anyone looking for a capture card, other than the
PVR-250/350 from hauppauge

PV-BT878P

>
> That machine wasn't exactly uber-powerful, but I didn't get the
> performance
> issues that you described. Perhaps a processor upgrade would be
> recommended
> for the Ebay link above, but 800MHz PIII's aren't exactly expensive. Not
> to
> mention, the Celeron in question is (apparently) easily overclockable.

Now that you mention it, I forgot to mention that choice of codec, bitrate
and capture resolution make a definite difference in processor you need.
The DivX codec is more processor intensive than rtjpeg. The above
described performance was in 480x480 Divx and I forget the bitrate.
480x480 is a pretty standard resolution. For the people with machines that
will handle it, most people seem to prefer 640x480. You can also go lower,
480x320 not being too bad of a drop, but slightly noticeable quality
difference. Much lower than that, and you definitely start to notice the
difference. To get MythTV to work on a P3-500 the recomened resolution
(for "live" TV) is about 352x240. From the mythtv.org documentation:

   * A PIII/733MHz system can encode one video stream using the MPEG-4
codec using 480x480 capture resolution. This does not allow for live TV
watching, but does allow for encoding video and then watching it later.
   * A PIII/800MHz system with 512MB RAM can encode one video stream using
the RTJPEG codec with 480x480 capture resolution and play it back
simultaneously, thereby allowing live TV watching.
   * A dual Celeron/450MHz is able to view a 480x480 MPEG-4/3300kbps file
created on a different system with 30% CPU usage.

I'm not sure why they included the mention of 512MB above... The general
rule seems to be that 128 is usually good enough, and anything over 256 is
unnecessary if you're running a single encode (and you can only run one
encode per capture card)

Of course, at that $50 price, if you had a beefier box you could use for
the backend, that box would make a nice frontend for MythTV.

For those who aren't familiar, MythTV works with any number of boxes,
backends being any box that does encoding, and a frontend being any box
that does displaying. You can actually set it up with a backend box with a
beefy processor and tons of disk space sitting in a closet doing all the
encoding (get a fast enough processor and a couple bttv cards, or multiple
PVR-250/350 cards and you can encode multiple streams at the same time)
and you'll never hear those fans and drive spinning. Then you can build a
couple of lower end computers with a nice slim case and uber-quite fans
that look good in your entertainment center for the front ends.
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