[mythtvnz] DVB multicasting

[Tortise]

----- Original Message ----- 
From: "Nick Rout" <nick.rout at gmail.com>
To: "MythTV in NZ" <mythtvnz at lists.linuxnut.co.nz>
Sent: Tuesday, October 27, 2009 2:25 PM
Subject: Re: [mythtvnz] DVB multicasting


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

>
> 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.
=========================
That was my assumption also, however experience proves it is dangerous to assume much - and asking the question may well help the 
questionee - by asking the right question.

>
> 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?

==========================
I think we'd agree myth does this well, however it largely ignores simultaneous broadcast of the same content.  (Live TV not so good 
either - there can be tuner lock issues limiting simultaneous viewing in a unicast paradigm)


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.
==========================
There is no myth provision for synchronised control / viewing on multiple frontends that I am aware of.  LIRC might be our friend 
here.


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).

============================
"Inherent delays" and "won't be synched" wrt multicast???  we'd be talking millisecond delays here, I'd not see that as a concern. 
How would that be a concern?


Synchronising even music within a LAN is hard enough, let alone video
as well.
=============================
Nick I understand mutlicast to be closely aligned to broadcast in this context, what is the synchronisation issue?  (e.g. vis-a-vis 
other broadcast media - what sync problems are there generally?)  Frontends are simply tuning into the same (UDP) stream, what is 
there to synchronise?  (Other than control)

So you're not going to achive synchronisation too easily,
============================
I am yet to be convinced.

why not let them watch independently, and let each room do its own comfort breaks.
=========================
They can now, however as some of us see an advantage in synchronisation I hope you'll consider what it may have to offer and support 
us in that.