[mythtvnz] DVB multicasting

[Nick Rout]

On Tue, Oct 27, 2009 at 1:40 PM,  <tortise at paradise.net.nz> wrote:
> ----- Original Message -----
> From: "Ross and Jemima Knudsen" <ross.jemima at gmail.com>
> To: "MythTV in NZ" <mythtvnz at lists.linuxnut.co.nz>
> Sent: Tuesday, October 27, 2009 10:46 AM
> Subject: [mythtvnz] DVB multicasting
>
>
> Hi all,
>
> I've been working on multicasting my FreeviewHD content on my LAN.  I've
> been using mumudvb which I've got up and running (last night).  It can
> multicast an entire transponder on the network for each card you have.
> I have two tuners so I managed to multicast the TVNZ and Canwest
> transponders together.  I was able to view all these channels using VLC
> on an Ubuntu and Windows 7 box over ethernet.  The wireless wasn't able
> to handle it (not sure why maybe the WPA overhead is too much).  Problem
> is now I want to get my mythbackend to 'tune' these channels.  I
> semi-followed JYAs howto here:
>
> http://avenard.com/iptv/Setup.html
>
> Using network recorder as the tuner card and using a m3u playlist to
> load the channels.  The whole backend setup seems to work without a
> hitch but when you try to watch live TV on the frontend it times out
> saying that I should have received a lock by now.  I'm not sure whether
> the problem is a OS configuration problem, a Myth problem or some other
> problem as the same m3u playlist file works with VLC on the same
> machine.  I wonder if it has something to do with subscribing to the
> multicast group.  This is my m3u file (the IP addresses are the default
> ones used by mumudvb):
>
> #EXTM3U
> #EXTINF:-1,TV ONE
> udp://@239.100.0.0:1234
> #EXTINF:-1,TV2
> udp://@239.100.0.1:1234
> #EXTINF:-1,TVNZ 6
> udp://@239.100.0.2:1234
> #EXTINF:-1,TVNZ 7
> udp://@239.100.0.3:1234
> #EXTINF:-1,TV3 PLUS 1
> udp://@239.100.1.0:1234
> #EXTINF:-1,TV3
> udp://@239.100.1.1:1234
> #EXTINF:-1,C4
> udp://@239.100.1.2:1234
>
> If I can get this to work then it means I can share my tuner hardware
> with the entire network.  It also means you could (if you wanted to) run
> mythbackend in a VM which would enable you to play around with various
> configurations...
>
> _______________________________________________
>
> Be nice if VLC had vdpau function to allow it to run on lower spec CPU's, I wait....however mplayer (and maybe myth?) also can
> display direct LAN streams.
>
> Hdhomeruns to some extent do what you may be seeking, all be it as a single networked device. There is also a TECH version which is
> specifically designed to multicast and a DVB-T one is I understand not far away....
>
> Makes me wonder what is the lowset spec CPU requirement for a DVB-T tuner(s) to exist solely for a network tuner device that mimics
> the Hdhomerun?
>
> It seems you are considering blasting the LAN with all channels, much like RF also works, however I am not sure the LAN has the
> capacity to cope with all that traffic, certainly ordinary wireless LAN is well understood to not cope at all well with multicast
> traffic.  When a (?optical) LAN can cope with all the traffic the need to control a tuner may diminish, however that seems to be the
> current design model.  Also with our 3 multi channels one could have 3 tuners, not so sure how it would work in the US with X
> channels?!
>
> Not sure what your goals are here, can you clarify the end goals?   What sort of config options did you want to play around with?

End goals it seems would be to broadcast live TV round the house so
any computer (running any OS) can get any of the live channels upon
demand, while at the same time having myth "tune" to those channels
for when you want to record something for posterity.

Quite handy for a number of users who can't get the "what is live TV
for anyway" paradigm. ie visitors 'expect' to turn the TV on and watch
whats playing now.

>
> I'd like to have a myth backend multicast its stream to frontends, so that other frontends could hop on to simultaneously play the
> same stream.... Control issues are likely to arise.   Perhaps it is a simple as using a multicast IP for the backend IP, I have yet
> to try that.

Mostly I would have thoght that the reason you have two frontends is
to allow for different people watching different things. Isn't the
whole idea of MythTV to cater to independent and different tastes in
the same household/user group?

OK there might be times when people want to watch the same thing at
the same time at different TV sets, but Myth doesn't stop you doing
that. Two (or more) frontends can watch the same recording at once.
They won't be synched, but they won't be under multicast either
(becasue different systems will have different inherent delays).
Synchronising even music within a LAN is hard enough, let alone video
as well. So you're not going to achive synchronisation too easily, why
not let them watch independently, and let each room do its own comfort
breaks.