[Open-graphics] AGP, PCI or PCI-express

[Dieter]

> > > > Very few machines that the OGC would go into have PCI-X.  So you only
> > > > get "plain" PCI.  And you have to share that 133 MBps with the other
> > > > PCI devices.  And lots of machines have other important
> > > > high-bandwidth devices on the PCI bus.
> > > >
> > > > That's fine for mostly static things like most desktop apps.  Email,
> > > > spreadsheet, image viewer, most web browser use, ...
> > > >
> > > > But many (most?) users are going to want to be able to watch video.
> > > > OGC is supposed to support 2 dual-link displays.  Last I read,
> > > > OGC is not going to have an mpeg decoder, and even the hw scaler has
> > > > been dropped.  Even if the CPU is fast enough (most will not be), and
> > > > even if you give 100% of the PCI bus to the OGC (not realistic), and
> > > > only driving 1 display, the bits just don't fit.
> > >
> > > We can use the drawing engine to do hardware scaling, and there will
> > > be=3D20 colourspace conversion. That is, we'll have hardware support fo=
> r=3D20
> > > XVideo. Most of the consumer cards in use today don't offer more than=
> =3D20
> > > that, and it works just fine here watching DVDs (Athlon XP 1700+,=3D20
> > > Radeon VE QY 32MB AGP).
> >
> > DVD is just SD.  Try 1920x1080.  Can the 1700+ and Radeon do that?
> > What is the CPU percent idle?
> 
> My system can't handle HD MPEG4 decoding and playback.  This a Radeon 9800X=
> T=20
> on AGP8x, with a Athlon 64 3200+ and a gig of RAM.  However, DVDs work just=
> =20
> fine.  I hypothesise that *any* HD playback requires either PCIe or PCI-X o=
> r=20
> on-graphics-card decoding and scaling to work.

Actual data!  Thank you!

Now, my notes say that AGP 8x is supposed to do 2133 MB/s.

1080p @ 24 bpp would need 373,248,000 bytes/sec.
1080p @ 32 bpp would need 497,664,000 bytes/sec.
Even a 30" display at 2560 x 1600 x32bpp @ 60Hz is "only" 983,040,000 B/s.

So AGP 8x should not be your problem.

I suspect that if you run "systat vmstat" or "top", it will say the
CPU is 100% busy.  And while a AMD64 3200+ is not the very fastest
CPU available, it is close.