On 7 Nov 02 at 9:43, v4l@xxxxxxxxxxxxxxx wrote:
> Wondering if anyone has opinions on how many TV capture cards a PCI
> bus will support running at 720x486 @ 29.97fps. I guess the question
> is, what is the bandwidth requirements of a 720x486 @ 29.97fps data
> stream and how much _sustained_ bandwidth does the average PCI bus
> have?
If you are going to use RGB32, you can have two with Intel motherboards
(if target is PCI/AGP/main memory), 1-2 with VIA (if target is PCI
or main memory), and 0-1 (bzzt, thanks for playing) with VIA if target
is AGP.
With some of YUV formats, which use about half of RGB32 bandwidth,
3 Bt848 definitely work with Intel 32bit 33MHz PCI (and I have no more
grabbers to check). But do not forget that usually you also want to
do some operations with data you grab: write them to disk, compress
and so on. If you are writting data to disk uncompressed, you'll have
problems with more than one grabber in the 32bit 33MHz PCI box.
> Maybe PVR-250 cards are really the only way to go if you want 3+
> simultaneous streams at full frame/full rate.
Yes. Unfortunately it looks like that Conexant CX23880/23881 still
support only 32bit 33MHz operations (spec says 132MBps). But from
spec it looks like that chip is ready to interface with MPEG2 hardware
encoder...
Petr Vandrovec
vandrove@xxxxxxxxxx
