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

warpme warpme at o2.pl
Fri Jul 30 10:55:08 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. 
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.

I'm really wonder of Your experience here.

BTW: What DVB-S2 channel You plan to receive: FTA or encrypted. If encrypted - welcome in not so well covered myth+encryption world. AFAIK: using CI+CAM prohibits multirecord as there is not so many CAMs able to decode multiple streams at once :-(


More information about the mythtv-users mailing list