Mailing List Archive: MythTV: Users

USB dvb-s(2) devices and multirec

Index | Next | Previous | View Threaded

lfsmailing at gmail

Jul 29, 2010, 4:01 AM

Post #1 of 7 (692 views)
Permalink

USB dvb-s(2) devices and multirec

Hi All,

I am considering to swap my PCI dvb-s(2) devices for usb dvb-s(2) devices.
The reason for considering is that usb devices can be used in a
virtual guest environment (VirtualBox in my case).

I hestitate in buying any usb dvb-s(2) devices since I cannot discover
if multirec on usb devices is supported like it is on some PCI
devices. Does anyone have experience with this?

Thanks,
Herman
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

anothersname at googlemail

Jul 29, 2010, 8:45 AM

Post #2 of 7 (663 views)
Permalink

Re: USB dvb-s(2) devices and multirec [In reply to]

On 29 July 2010 12:01, Herman Gerritsen <lfsmailing [at] gmail> wrote:
> Hi All,
>
> I am considering to swap my PCI dvb-s(2) devices for usb dvb-s(2) devices.
> The reason for considering is that usb devices can be used in a
> virtual guest environment (VirtualBox in my case).
>
> I hestitate in buying any usb dvb-s(2) devices since I cannot discover
> if multirec on usb devices is supported like it is on some PCI
> devices. Does anyone have experience with this?
>
> Thanks,
> Herman
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>

Herman

Funnily enough I've been playing with this with regards to DVB-T at the moment.

The USB support in Virtualbox isn't as great as you might hope, I've
had success with some USB devices and not with others. At the same
time I tried with a trial version of VMWare and have found that while
VMWare support for USB devices seems better then Virtualbox it's still
not perfect.

I'd be interested to see what success you have with DVB-S(2) devices.

Regards
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

lfsmailing at gmail

Jul 29, 2010, 11:11 AM

Post #3 of 7 (661 views)
Permalink

Re: USB dvb-s(2) devices and multirec [In reply to]

> Funnily enough I've been playing with this with regards to DVB-T at the moment.
>
> The USB support in Virtualbox isn't as great as you might hope, I've
> had success with some USB devices and not with others. At the same
> time I tried with a trial version of VMWare and have found that while
> VMWare support for USB devices seems better then Virtualbox it's still
> not perfect.
I currently have an USB card reader (smargo) in a virtual machine that
works without problems.
So I got enthusiastic and started thinking of the possibilities with
usb dvb devices.
I just do not want to buy any usb dvb device unless I am sure it is
supported and has the multirec possibility.
Just hope it is gonna work.
>
> I'd be interested to see what success you have with DVB-S(2) devices.
I will post results here, if i have a usb dvb device :)

Greetings,
Herman
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

knowledgejunkie at gmail

Jul 29, 2010, 12:27 PM

Post #4 of 7 (653 views)
Permalink

Re: USB dvb-s(2) devices and multirec [In reply to]

On 29 July 2010 12:01, Herman Gerritsen <lfsmailing [at] gmail> wrote:

> I hestitate in buying any usb dvb-s(2) devices since I cannot discover
> if multirec on usb devices is supported like it is on some PCI
> devices. Does anyone have experience with this?

If a DVB tuner can pass the received transport stream to a consuming
application, multirec can be used. If the DVB tuner PID-filters the
stream to pass only a single program, multirec cannot be used as the
application will only see a single program stream.

PCI tuners have sufficient bandwidth to pass the whole transport
stream, whereas early USB 1.1 tuners did not and PID-filtered the
transport stream. USB 2.0 (and later) DVB tuners have sufficient
bandwidth to pass the whole stream - whether they do or not is down to
how each device was designed and implemented. All of the PCI DVB-T/S
tuners I've tried at home (admittedly a small sample) have supported
multirec. I don't have any DVB-S2 to test.

Cheers,
Nick

--
Nick Morrott

MythTV Official wiki: http://mythtv.org/wiki/
MythTV users list archive: http://www.gossamer-threads.com/lists/mythtv/users

"An investment in knowledge always pays the best interest." - Benjamin Franklin
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

lfsmailing at gmail

Jul 29, 2010, 10:34 PM

Post #5 of 7 (643 views)
Permalink

Re: USB dvb-s(2) devices and multirec [In reply to]

> If a DVB tuner can pass the received transport stream to a consuming
> application, multirec can be used. If the DVB tuner PID-filters the
> stream to pass only a single program, multirec cannot be used as the
> application will only see a single program stream.
>
> PCI tuners have sufficient bandwidth to pass the whole transport
> stream, whereas early USB 1.1 tuners did not and PID-filtered the
> transport stream. USB 2.0 (and later) DVB tuners have sufficient
> bandwidth to pass the whole stream - whether they do or not is down to
> how each device was designed and implemented. All of the PCI DVB-T/S
> tuners I've tried at home (admittedly a small sample) have supported
> multirec. I don't have any DVB-S2 to test.

Reading you reasoning above it seems logical that most (or even all)
usb2.0 dvb tuners should work with multirec since they are
(so called) budget systems (I think).

From the www.linuxtv.org web site I found that the TT S2-3600
(http://www.linuxtv.org/wiki/index.php/TechnoTrend_TT-connect_S2-3600)
does pass the complete transport stream to the software:
(dvb-usb: will pass the complete MPEG2 transport stream to
the software demuxer.)
Yet this device is in the UnSupported section, but I have seen threads
discussing succes with dvb-s and dvb-s2 with this device (in linux)

Does anyone use this type of device (TechnoTrend Connect S2-3600)
or knows what its current status is.
Since I can not purchase one of the supported USB devices
(or any way did not find these in my neighborhood)

Thanks,
Herman
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

warpme at o2

Jul 30, 2010, 3:55 AM

Post #6 of 7 (632 views)
Permalink

Re: USB dvb-s(2) devices and multirec [In reply to]

Hi,

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 [at] linuxtv/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.

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 :-(

br
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

lfsmailing at gmail

Jul 30, 2010, 2:38 PM

Post #7 of 7 (612 views)
Permalink

Re: USB dvb-s(2) devices and multirec [In reply to]

> 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 [at] linuxtv/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.
Hmm..
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 :(

Greetings,
Herman Gerritsen
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

Index | Next | Previous | View Threaded

Interested in having your list archived? Contact Gossamer Threads