[mythtv-users] Frontend vs. backend: Which one needs to be faster?

[Steve Hayles (diverse)]

It will depend on what capture card you use and what video format you wish
to use and what resolution and bitrates are involved

For instance a PVR-250 card has a built in hardware encoder which means that
the backend will have to do very little work to encode the video.  A
frontend would then need to be powerful enough to decode the MPEG stream.

If you use a DVB card in the backend then the CPU requirements are very low
as the incoming signal is already in MPEG format and the backend needs to
only write the data to disk. (Beware very old machines though that do not
tend to have Hard Disk controllers capable of DMA transfers which will mean
that the reading and writing of data is too slow)

If the capture card is not capable of hardware encoding (a framegrabbing
card based on the comon BT848 or 878 capture cjip) A PIII 733MHZ machine can
encode video at about 480x480 but will not be able to play it back live. 

If you want to run a backend on your PIII 866 machine,  make sure it is
capable of DMA transfers and try and use a capture card that can encode
video in hardware.

The faster the hardware is the better the experience you will have but if I
had to choose I would prefer a faster Frontend and make sure the backend is
setup as I describe above.  MythTV is a very flexible design, and can
opearate in a great many different configurations so you should listen to
other views that you get from other users.

Steve Hayles



-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Footer
Sent: 26 November 2004 09:54 PM
To: Discussion about mythtv
Subject: [mythtv-users] Frontend vs. backend: Which one needs to be faster?

I'm going to be upgrading my Myth box very soon.  But I was hoping to keep
my old, tired, slow PIII 866mhz as either my frontend or backend.
 Due to video issues, it will probably have to be the backend.

The question I have is which box needs to be faster?  Hopefully the answer
will be frontend ... ?

Thanks in advance for any opinions!

TLD


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