[mythtv-users] CPU power for digital tuners

[Gert van der Knokke]

Jon Whitear wrote:

>CPU power isn't going to be an issue for a backend only box. I have one
>DVB-T in my P3 500, and that uses about 6% CPU while recording. On the
>other hand, general throughput (e.g. PCI bus, HDD) might become a
>problem. Here in Oz, SD broadcasts are about 6Mbit/s, and I think HD are
>10-12. If you've got a few cards recording HDTV at the same time, you'll
>want to make sure you've got a pretty quick disk subsystem.
>  
>
Here we go again with the Mbit/MByte mixups... :-)

6 Megabit per second is about 0.75 Megabyte per second (6/8) and since 
most HD read/write performance is measured in megaBYTES per second not 
megaBITS it means that any harddisk available nowadays can handle this 
with no problem at all. Some of the later UDMA drives do over 40 
MegaBYTES per second in writing... so you can theoretically record 
several streams at once.
Still, with quite a few devices accessing the PCI bus, timing problems 
are sometimes an issue.
With newer motherboards the main IDE controllers are no longer connected 
to the PCI bus and thus do not interrupt or interfere with PCI traffic.
 
Gert