[mythtv-users] HDHomeRun like device for analog?
Brian J. Murrell
brian at interlinx.bc.ca
Fri May 14 14:57:27 UTC 2010
On Fri, 2010-05-14 at 08:38 -0600, Brian Wood wrote:
> If you use a standard PCI card, be aware that the PCI bus may become a
> bottleneck under some circumstances.
Indeed. This is a concept I have been struggling with. The mobo in my
FE/BE has 5-6 PCI slots and an AGP slot. I liked the idea of VDPAU
until I heard PCI was going to be my only option.
> If you are playing back something that
> VDPAU can't help with (feature set "B" only helps with MPEG2 and h264, feature
> set "C" can do more, like VC-1, I think), you may have to move more data than
> the bus can cope with, especially if you are using multiple PCI capture
> devices at the same time.
That's me. Well, the multiple PCI capture cards part, anyway. I have 3
cards, which amounts to 4 tuners.
> So the PCI VDPAU cards work fine, as long as you are using VDPAU, but if you're
> not, it's just a slow old video card. VC-1 HD with a feature set "B" card, for
> example, might be problematical.
What is VC-1 and when might I run into it? And how much bus bandwidth
does it need to carry it to a video card, post-decoding (i.e. if your
VDPAU card cannot handle it)?
But to get back on topic, just how much PCI bus bandwidth are we talking
Let's say I have 4 (Hauppage MPEG-2 encoder card) recordings all going
on at once and an MPEG2 playback (i.e. the result of a recording from an
Hauppage PVR card) using VDPAU all going at the same time. Where am I
in terms of bus saturation?
My recorded files are 2.17GiB/h, which by my math equals 633KiB/s or
4.9Mib/s. So, my guess is that to have 4 recording and 1 playing, I am
According to http://en.wikipedia.org/wiki/Conventional_PCI PCI is
capable of 133MB/s. So am I as in the clear as I think I am? Only
using about 1/5 of the bandwidth available?
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