[mythtv-users] Which USB DVB-T Device should I choose, in a 266Mhz Linux Box

Sarah Hayes sarah at sarahhayes.is-a-geek.net
Mon Feb 18 14:28:44 UTC 2008

Steve Smith wrote:
> On 18/02/2008, *Sarah Hayes* <sarah at sarahhayes.is-a-geek.net 
> <mailto:sarah at sarahhayes.is-a-geek.net>> wrote:
>     Guan Xuefei wrote:
>     > Hello folks, I am new to MythTV, I have a old linux box (266MHz
>     CPU),
>     > I would like to choose a USB DVB-T box, and It should have the
>     > hardware encoder because the poor CPU, I checked the mythtv website,
>     > and it takes me to here,
>     > http://www.linuxtv.org/wiki/index.php/DVB-T_USB_Devices, a lot of
>     > devices for me to choose, If anyone have ever use those devices,
>     > please give me some advices. Thanks.
>     >
>     > Guan,
>     Whilst, yes, DVB cards require very little to no CPU overhead, I'd be
>     dubious of using a USB one on such a beastie.
>     A lot of them I've encountered seem to be USB2 not USB1 or 1.1 (and
>     yes, I've encountered old boards that were pre-usb spec with what
>     amounts to the USB equivalent of early pre-N on them... i.e. nowt
>     worked
>     properly with anyone else's stuff), backwards compatibility is one
>     thing
>     but volume of data another.  I'm also dubious because USB devices do
>     seem to take a hit on the CPU and well, you'll have the data stream
>     being written to the disk; can it cope?
>     A good question to ask is "How much throughput does a disk need to
>     write
>     an mpeg2/whatever it appears as stream?" and compare the average
>     against
>     a hdparm -tT /dev/hda if the result is higher you're ok, if not,
>     you'll
>     possibly be dropping frames on recording.
>     Is this little machine going to be an "all-in-one"?  If so keep in
>     mind
>     that MySQL will be running on it and both the frontend and backend
>     programs, so you might want to max the memory on the system; which is
>     probably PC100/133 SDRAM and thus dirt cheap.  Being an older board it
>     probably won't take all that much so not an expensive proposition :)
>     Would it work?  Probably.  Would it be a good long term solution?
>     Probably not, but handy for figuring out if MythTV is for you and then
>     throwing bigger (but not necessarily cutting edge) hardware at it,
>     say a
>     PIII or early P4 for both recording and perfect playback :)
>     Sarah
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> A 266Mhz machine could make an OK Mythbox backend with the addition of 
> a MediaMVP to do the playback.
> (I used to run GBPVR on an early 800mhz mini-itx which was incapable 
> of playing mpeg2 so I used that as the recorder and MediaMVP as my 
> playback device).
> Though as others have suggested I'd go for a PCI based DVB-T device as 
> the USB solution may place too much load on the CPU (+ you'd probably 
> need a USB2 card anyway).
> So nip on over to ebay and pick yourself a second hand MVP....
> or if you want an all in one box solution, ditch the PII machine and 
> buy a second hand P3/P4/Athlon etc
> (P3 700mhz+ is sufficient for SD, some have used less!)
Odd, I thought all the early EPIA's had mpeg2 acceleration with the 
right patches to mplayer?

Before splunking for the PCI card I'd double check it'll work in the PCI 
slots; again compatibility between differing revisions of the PCI spec 
can be hit & miss (found that out the hard way myself).  But a squint at 
the manual or googling the chipset will quickly sort that out that question.


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