Mailing List Archive

What's your setup? Unless you're using a hardware-encoding card like the
Hauppauge PVR-250/350 or the Matrox G400, even a P3-667 is a bit weak for
watching LiveTV at anything but the lowest resolution & quality capture
settings. If you're trying to do anything more than 320x240 RTJPEG, you're
probably pegging your CPU (again, unless you've got a hardware encoder). A
general rule of thumb for high-quality (480x480 or higher) encoding with a
standard V4L card is 1GHz per tuner + ~500MHz per playback stream. (So, 1
tuner in a frontend/backend machine = minimum 1GHz, 2 tuners = 2.5GHz (3GHz
if you want PIP). Those are optimal specs; you can get away with less, but
667MHz still sounds a bit light.

As far as recompiling, you probably won't get much of a performance increase
merely by recompiling. The optimizations that truly make a difference for
Myth are MMX-related; both the P2 & P3 support MMX (IIRC).

Someone please correct me if I've misspoken...

-JAC

> -----Original Message-----
> From: mythtv-users-bounces@snowman.net
> [mailto:mythtv-users-bounces@snowman.net]On Behalf Of dmezzetti
> Sent: Friday, May 30, 2003 10:33 AM
> To: mythtv-users@snowman.net
> Subject: [mythtv-users] mythtv recompile because of new CPU
>
>
> Do I have to recompile MythTV if I use another CPU ? I compiled it on a
> Pentium 2-350 MHz but it was way to slow watching Live-TV. Now I built
> in another Mainboard with a Pentium 3-667 MHz. Maybe it's still too slow
> but should be faster than the Pentium 2. MythTV is running without
> recompile but I'm not sure if it uses all the features of the P3 CPU ??

On Fri, May 30, 2003 at 11:07:12AM -0400, Joseph A. Caputo wrote:
> general rule of thumb for high-quality (480x480 or higher) encoding with a
> standard V4L card is 1GHz per tuner + ~500MHz per playback stream. (So, 1
> tuner in a frontend/backend machine = minimum 1GHz, 2 tuners = 2.5GHz (3GHz
> if you want PIP). Those are optimal specs; you can get away with less, but
> 667MHz still sounds a bit light.

Thanks for these rules...

How about if you add a PVR 250? A PVR and a non-PVR tuner ...?

Kind Regards,
Frank Louwers

--
Openminds bvba www.openminds.be
Tweebruggenstraat 16 - 9000 Gent - Belgium

Well, I'm sure others have varying experiences, but I'd guess that since a
PVR-250 puts very little load on the CPU, you could get away with (almost)
leaving it out of the CPU equation. So for a frontend/backend with single
PVR-250, you might be able to get away with a 500MHz machine; with a PVR-250
& a V4L tuner, maybe 1.5GHz (2GHz for PIP). Again, you can get away with
less if you turn down the capture size/quality on the V4L card. Also, keep
in mind that with a PVR-250/350 your disk space requirements will go up.

-JAC

> -----Original Message-----
> From: mythtv-users-bounces@snowman.net
> [mailto:mythtv-users-bounces@snowman.net]On Behalf Of Frank Louwers
> Sent: Friday, May 30, 2003 11:30 AM
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] mythtv recompile because of new CPU
>
>
> Thanks for these rules...
>
> How about if you add a PVR 250? A PVR and a non-PVR tuner ...?
>
> Kind Regards,
> Frank Louwers

I only have a standard miro PCTV. I thought about buying a PVR-250 but I
only have very bad TV quality
because I have stolen cable TV from my Grandma and I have about 20
metres cable lying through the whole house.
The cable TV is only for my computer. My real TV uses a satellite
dish.But MythTV is so great that I plan on using it
on my real TV and with the bad image quality I have there's no
difference if I use 320x240 or 480x480. So best
hardware solution for me would be something like a PVR-250 with a Sat-Tuner.

About recompiling. Sure, both CPU have MMX but only the P3 has SSE. Does
Mythtv use SSE ?

Joseph A. Caputo schrieb:

>What's your setup? Unless you're using a hardware-encoding card like the
>Hauppauge PVR-250/350 or the Matrox G400, even a P3-667 is a bit weak for
>watching LiveTV at anything but the lowest resolution & quality capture
>settings. If you're trying to do anything more than 320x240 RTJPEG, you're
>probably pegging your CPU (again, unless you've got a hardware encoder). A
>general rule of thumb for high-quality (480x480 or higher) encoding with a
>standard V4L card is 1GHz per tuner + ~500MHz per playback stream. (So, 1
>tuner in a frontend/backend machine = minimum 1GHz, 2 tuners = 2.5GHz (3GHz
>if you want PIP). Those are optimal specs; you can get away with less, but
>667MHz still sounds a bit light.
>
>As far as recompiling, you probably won't get much of a performance increase
>merely by recompiling. The optimizations that truly make a difference for
>Myth are MMX-related; both the P2 & P3 support MMX (IIRC).
>
>Someone please correct me if I've misspoken...
>
>-JAC
>
>
>
>>-----Original Message-----
>>From: mythtv-users-bounces@snowman.net
>>[mailto:mythtv-users-bounces@snowman.net]On Behalf Of dmezzetti
>>Sent: Friday, May 30, 2003 10:33 AM
>>To: mythtv-users@snowman.net
>>Subject: [mythtv-users] mythtv recompile because of new CPU
>>
>>
>>Do I have to recompile MythTV if I use another CPU ? I compiled it on a
>>Pentium 2-350 MHz but it was way to slow watching Live-TV. Now I built
>>in another Mainboard with a Pentium 3-667 MHz. Maybe it's still too slow
>>but should be faster than the Pentium 2. MythTV is running without
>>recompile but I'm not sure if it uses all the features of the P3 CPU ??
>>
>>
>
>_______________________________________________
>mythtv-users mailing list
>mythtv-users@snowman.net
>http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
>
>
>

I don't think so... the default settings.pro distributed with Myth specifies
the option "-march=pentiumpro", which IIRC doesn't have SSE (certainly if
the P2 doesn't have it!)

-JAC

> -----Original Message-----
> From: mythtv-users-bounces@snowman.net
> [mailto:mythtv-users-bounces@snowman.net]On Behalf Of dmezzetti
> Sent: Friday, May 30, 2003 2:09 PM
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] mythtv recompile because of new CPU
>
>
> About recompiling. Sure, both CPU have MMX but only the P3 has SSE. Does
> Mythtv use SSE ?
>