On Mon, 21 Aug 2006 09:17:54 +0100
Dieter <[EMAIL PROTECTED]> wrote:
> 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.
Believe me that the PCI bus is fast enough to handle 720p/i content.
I was able to watch a 720i mpeg2 file on a duron 950MHz with an
Matrox G550 with MPlayer and mga_vid. Worked smoothly unless i
tried to deinterlace it in software (mostly because mga_vid does
not allow DMA and thus steals CPU time for the data transfere).
1080p/i content is another case. It needs at least 89MByte/s
in the 4:2:0 case and 120MByte/s in the 4:2:2 case (both at 30fps).
This about the limit of what most systems can handle on continous
data rate on the PCI bus. Thus it will only be possible if the
system (including hardware and software) is well designed and
optimized for this use case.
But considering the availability of HDTV content on
the net, i assume that it will still take a few years
until watching HDTV content becomes a common use.
Beside, there is a workaround without too much visible quality los:
half size decoding (ie skip every second line).
> But many (most?) users are going to want to be able to watch video.
> OGC is supposed to support 2 dual-link displays.
Watching two high resolution videos at the same time is very uncommon.
> Last I read,
> OGC is not going to have an mpeg decoder,
Too big, to little use
> and even the hw scaler has been dropped.
Not dropped, just moved somewhere else. Ie it will not
be a classical back end scaler but embeded into the
3D functionality.
> 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.
It fits, believe me.
OGC might be slow compared to other cards on the market, but
it's not outdated by 10 years[1]. And there are a few people from
the video coding/video application camp on this list who will
keep an eye on this kind of stuff.
Attila Kinali
[1] as a side note, the G550 used here as comparison is
now 6 years old (IIRC). The G450 on which it is based
(aka very similar) is two or three years older.
Interestingly, there is a PCI-e version of the G550.
Now talk about short product live times in the PC market :)
--
心をこめて聞け心をこめて話せ
_______________________________________________
Open-graphics mailing list
[email protected]
http://lists.duskglow.com/mailman/listinfo/open-graphics
List service provided by Duskglow Consulting, LLC (www.duskglow.com)
