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Date:      Wed, 10 Sep 1997 21:04:07 -0400
From:      Randall Hopper <rhh@ct.picker.com>
To:        Denis DeLaRoca <CSP1DWD@MVS.OAC.UCLA.EDU>
Cc:        multimedia@FreeBSD.ORG
Subject:   Re: FreeBSD 3.0 -current Bt848 Video Capture and Sound Driver Release
Message-ID:  <19970910210407.46529@ct.picker.com>
In-Reply-To: <199708190700.AAA16529@hub.freebsd.org>; from Denis DeLaRoca on Tue, Aug 19, 1997 at 12:00:00AM -0800
References:  <199708190700.AAA16529@hub.freebsd.org>

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Denis DeLaRoca:
 |Amancio Hasty:
 |> The Bt848 chipset is known to work with Pentium / Triton II and Pentium
 |> Pro / Natoma. Other chipset combinations have proven to be problematic.
 |>
 |> With at least a Pentium / Triton II you can  display 640x480x32 at 30
 |> fps on a decent video card such as matrox millenium (vram) or
 |> an S3 968 with VRAM. dram based video cards work okay however they tend not
 |> to have the necessary bandwith for full resolution  video playback.
 |
 |Humm? I looked at the project's web pages but I don't find a list of
 |what chipset combinations have proven problemmatic. So let me ask
 |about what motherboards can folks report as working fine. How about
 |the Intel Triton 430TX/430HX/430VX motherboards? How about the Pentium
 |II motherboards? Is it just a question of performance to achieve 30fps
 |where the above problems appear?

Sorry so long in getting to a reply.  I haven't gone through my multimedia
mail folder in a while.

To your last question first (30fps problems), as I recall the folks having
the most trouble seemed to be those with old 486 PCI chipsets and off-brand
motherboards.  The main criteria for best performance watching 30fps on
your monitor (via direct video; aka PCI-to-PCI DMA):

    1) a PCI motherboard and MB chipset with solid busmastered DMA 
       performance, and
    2) a video card having hi- or true-color in standard byte-orders that
       is supported by the XFree DGA extension (i.e. one that XFree
       memory-maps the frame buffer for and supports querying through the
       DGA extension).

If your video card supports direct video, CPU speed isn't relevant to 30fps
display performance so you can ignore that.  If it "doesn't" support direct
video however, then the CPU has to get involved in transfering frames to
the display, so then CPU is relevant.

If you have a video board purchase in mind, someone on the list might have
tried the ones on your candidate list and can help out with what to expect.
So you might post about that.  Good results have been had with the S3968
and S3 Virge and Virge/VX cards.

And to your question regarding hardware good-results and tips:

A while back, John-Mark started a bt848 hardware survey page (...let's
see...ah, found it):

   http://www.freebsd.org/~jmg/cgi-bin/bt848.cgi

that's still there and has some entries on it.  You might check that out
for some ideas.

For myself, I've run my Wincast/TV with a STB Velocity 3D (S3 Virge/VX
chipset) on both a Triton 1 & Triton 2 motherboard (ASUS P55TP4XE and
P55T2P4) @ 66Mhz (33MHz PCI) all the way up to 83MHz (41.5Mhz PCI) on the
T2P4.  Both cards had no trouble at all with the faster bus; direct video
(PCI-PCI DMA) worked fine without any hitches and great performance on both
MBs with a P100 (and now as well on the T2P4 with my new P233MMX).  I'm a
satisfied Hauppauge/STB/Asus customer.

Randall Hopper




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