[linux-dvb] Re: dec2000-t success

[Holger Waechtler <holger@convergence.de>]

Franck Arnaud wrote:
> Douglas Kosovic:
>
> > > > the DEC 2000-t's USB 1.1 interface will impose a 12 Mbits/s limit on
> [...]
>
> > At least the Australian SDTV 576i channels which are 6 Mbit/s, should work.
>
> If you don't move your USB mouse too much though :-). If I'm not 
> mistaken, when a USB low-speed device uses say 1/2 of its low speed 
> bandwidth it also takes 1/2 of the bandwith of high speed devices 
> on the same bus.
Isochronous transfers can allocate a guaranteed bandwidth up to 80% of 
the overall bus bandwidth. Bulk, Interrupt and control transfers will 
then fill the remaining 20% and get delayed if there is too much traffic 
right now.


> Also how successful is USB at achieving nominal rates in practice, 
> especially when there are multiple devices?
At least for USB1.1 one DVB receiver is enough to saturate the bus...

Holger



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