[mythtv-users] CPU power and decoding
Jay R. Ashworth
jra at baylink.com
Thu Sep 30 14:31:25 EDT 2004
On Thu, Sep 30, 2004 at 02:40:59PM +0200, Milos Prudek wrote:
> I would like to build a MythTV box (frontend/backend in one PC). Are the
> following sentences true or false?
> - DVB broadcasts in MPEG-2; consequently there is no encoding taking
> place when saving a DVB broadcast to disc.
Correct. Or at least, it *can* be correct; there's a possibility that
it might depend on the chosen tuner card.
> - When watching a DVB broadcast, the CPU must decode MPEG-2, or the DVB
> card's onboard hardware MPEG-2 decoding takes place.
*Something* certainly must decode it, yes; there's a possibility the
DVB card might have an MPEG decoder, and there's an (even smaller)
possibility that there might be a way to access said decoder from
> - When watching an analog TV broadcast, no significant decoding takes
> place and the burden on the CPU is very light.
If you're bypassing the box, this is true. If you want to use the
fancy features<tm> of myth WRT live broadcast, then it is not: you will
be simultaneously recording (to the ring buffer, if not to a recording
file) *and* playing back.
> - When recording an analog TV broadcast, the encoding done in software
> via CPU will consume less than 1GHz of processing power.
This depends on the tuner card as well: hardware MPEG cards like the
Hauppauge, AVer 179 and Yuan do indeed consume little horsepower
because, like the DVB cards, they output precompressed MPEG-2 -- they
do it by having an onboard co-processor that does the hard work,
converting electricty into heat.
> - When watching a DVB broadcast, the decoding done in software via CPU
> will consume less than 1GHz of processing power.
Can't speak to this one. Can you software-decode NTSC-rate MPEG2 in a
> - When buying both a DVB card (the new SkyStar1 CI) and an analog
> terrestrial TV card, I will need only one remote control (for example
> the SkyStar's remote control), and I will be able to control the whole
> MythTV with it, i.e. both the DVB and analog card.
> - It is actually possible to have a wireless IR keyboard, wireless IR
> mouse and IR remote control, all working, not disrupting each other
> (equipment recommendations/buying advice welcome).
This depends to a certain amount on the exact devices involved, but if
the IR itself doesn't conflict, nothing else will.
Jay R. Ashworth jra at baylink.com
Designer Baylink RFC 2100
Ashworth & Associates The Things I Think '87 e24
St Petersburg FL USA http://baylink.pitas.com +1 727 647 1274
"You know: I'm a fan of photosynthesis as much as the next guy,
but if God merely wanted us to smell the flowers, he wouldn't
have invented a 3GHz microprocessor and a 3D graphics board."
-- Luke Girardi
More information about the mythtv-users