[mythtv-users] USB dvb-s(2) devices and multirec

Herman Gerritsen lfsmailing at gmail.com
Fri Jul 30 21:38:07 UTC 2010

> I have some experience with ProfTuners 7500 DVB-S2 tuner.
> Basically it works oob with 2.6.34 kernel. For older ones You need patch.
> http://www.mail-archive.com/linuxtv-commits@linuxtv.org/msg06205.html
> I haven't time to extensively test it, but tuner/demodulator (STB6100+STV0903) of this dev are well supported
> (I have 2x such combination on PCI cards in production system and works well 24/7 last 3 months).
> Regarding USB in virtualized enviroment:
> AFAIK USB has few operating modes like:
> -isochronous  (transfers guaranteed data rate)
> -interrupt (when guaranteed quick responses  and bounded latency is needed)
> -bulk (large sporadic transfers using all remaining available bandwidth)
> -control (typically used for short, simple commands to the device, and a status response)
> Logic says me that for multimedia (like DVB stream) isochroneous mode is designed and should be used.
> Unfortunately this is real time mode and usually it is very difficult to reliably implement relatime system in virtual time enviroment (virtualization is classical example of virtual time systems).
> So reliability of myth BE running on VM and communicating across virtualized IO might be challenge.
Sounds like I really want to borrow a device before I start buying them...

> I'm really wonder of Your experience here.
I will start looking around to borrow something somewhere :D
On the other hand maybe I will just plunge in if my familiy lets me... :)
Experimenting with the television is not well supported here :(

Herman Gerritsen

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