[mythtv-users] recommend PCI DVB-T Tuner Card?

[Devin Heitmueller]

On Wed, May 5, 2010 at 9:01 PM,  <lindsay.mathieson at gmail.com> wrote:
>
> On Thursday 06/05/2010 at 10:31 am, Ed W wrote:
>
> I have one of these as a trial:
>       http://www.amazon.co.uk/gp/product/B001RP6YL6/ref=oss_product
>       (PEAK External Dual Channel DVB-T TV Tuner)
>
> Seems to be working ok and I'm going to buy 2 more and see what
> happens... I believe that this may be really saturating the USB bus, but
> I am not sure what tool I can use to check that? I don't have much else
> interesting connected though
>
> The USB bus has way more bandwidth than is needed for HD, you could have 4
> HD tuners recording simultaneously with no problems. From memory, your
> average HD channel maxes out at 50 Mbs, even for 1080p, whereas USB 2.0 has
> 480Mbs availble.

Unfortunately, the theoretical doesn't really match real life that
closely.  Given crappy driver optimization under Linux for most
boards, you're not likely to get more than two to stream HD reliably
at the same time.  And be prepared to get a powered USB hub, since
even a single tuner draws pretty close to the 500ma limit while
streaming (thereby hitting the power limit on a single port).

Also bear in mind that most of the USB tuners simply are not designed
for 24x7 operation (cost is a key concern).  They're great for casual
"I want to watch some TV on my laptop once in a while", but I would
definitely think twice about using them for a MythTV box.

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com