[mythtv] Memory bandwith

[Bryce C]

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My only stuttering is at the very beginning of watching the video for a
few secs and when watching live tv where it stutters every 30 secs or so
but pausing for a second  helps greatly.  It's aan old 13Gb drive anyway
and i'll be getting a new, really big drive in a couple weeks.  I'll
also look into the pci latency setting.


On Fri, 2003-01-03 at 17:51, Calvin Harrigan wrote:
> On Fri, 2003-01-03 at 19:29, Monty Walls wrote:
> > On 03 Jan 2003 19:22:12 -0500
> > Calvin Harrigan <calvinharrigan@earthlink.net> wrote:
> >=20
> > [snip]=20
> > > I wouldn't say that memory bandwidth doesn't make a difference, but I
> > > think the problem may lay else where, processing power perhaps?
> > >=20
> > > The PCI bandwith is theoretically 32bits(4bytes) x 33MHz or around
> > > 130MBs per/s.  640x480x16bits(yuv)x30fps =3D 18.MBs/s.  PCI should be=
 able
> > > to resonably handle the tv card even if it's only getting 75 percent =
of
> > > it's maximum yield.  I currently use a XP1800 with 256 megs of PC133 =
on
> > > an MSI kT133 board and it works quite well, not stuttering or any of =
the
> > > sort.  I can watch live TV, record and playback simultaneously (outsi=
de
> > > livetv) without a hiccup.
> > >=20
> > > I should note that you might try increasing the PCI latency in the bi=
os,
> > > it helped me some in smoothing out my system.  It was not so much a
> > > question of bandwidth, but more of bus contention, by increasing the
> > > latency devices can hold the bus a bit longer to transfer data, or
> > > somthing like that...  Getting forgetful in my old age.
> >=20
> > The KT133 chip set max's out at about 69mb/s without the latency patche=
s,
> > some raid benchmarks last year tripped over VIA pci/dma bandwidth limit=
ations.
> >=20
> > Doing RTjpeg, I can reduce the quality and stop the stuttering.  So for=
 my
> > old board it looks like a pci/latency issue.=20
> >=20
> > Try using RTjpeg to the increase data-rates over the bus, instead of
> > mpeg4.  Mpeg4 gets your pci data rates low enough that it's not a probl=
em.
> > You may find stuttering under RTjpeg. At least that was my experience.
> >=20
> >=20
> >=20
> >=20
> I tried both rtjpeg and mpeg4, both work well but I get better quality
> with mpeg4.  I haven't had a problem with stuttering since I got my
> hardrive running in udma mode.
>=20
> Calvin...
>=20
>=20
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--=20
Bryce C <Plug@BryceCo.Net>
CoBryce Communications

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