[mythtv-users] Way out idea on watching same thing in multiplerooms

Tortise tortise at paradise.net.nz
Mon Jan 4 09:24:29 UTC 2010


----- Original Message ----- 
From: "Nick Rout" <nick.rout at gmail.com>
To: "Discussion about mythtv" <mythtv-users at mythtv.org>
Sent: Monday, January 04, 2010 9:03 PM
Subject: Re: [mythtv-users] Way out idea on watching same thing in multiplerooms


On Mon, Jan 4, 2010 at 5:04 PM, Christopher X. Candreva
<chris at westnet.com> wrote:
> On Mon, 4 Jan 2010, tortise at paradise.net.nz wrote:
>
>> this might work. I think the elegant and proper answer lies in multicast
>> streams, either from the FE or perhaps preferably the BE. Using multicast
>> quite simply avoids any sync issues. Nick Rout made a suggestion that
>
> I don't think so. Think of two playback units with different sized buffers.
> Without sync data they can be at different points in the multicast stream.
> The stream starts comming in at the same time, but a system waiting for a
> (say) 20 meg buffer to fill will start after one waiting for a 10meg buffer
> to fill. Then when the master pauses, will simple tell the others
> to pause too ?

In my case, Yes!

 If the master decides to rewind to hear the last line again,
> will the other follow ?

In my case, Yes!

If the clients are not synchronised all the time, then there would be no point in using multicast.  I was seeking all clients 
synchronised, which is one reason I see multicast as a good option.

>
> Multicast solves a different problem, not sending the same data over the
> network two or three times. Perhaps for a situation where you had 20 or more
> screens to sync (like a mall I was in recently with monitors showing the
> same cartoons everywhere) that might be usefull. I don't think the average
> 100mbit home network is going to be overloaded by 2 or 3 machines watching
> at once.
>
> Again thinking broadly, and I know I'm going to mix metaphores here, what
> I'm suggesting should be possible by piping something like the regular
> standard out text stream of mplayer into the telnet interface of a myth
> frontend. All it has to say is play this, and this is where in the media you
> want to be.
>
> How to access it -- NFS, SMB, multicast stream, or even a copy of the same
> file on a local disk -- is a separate problem.

>I entirely agree with you, my contribution to tortise's other thread
was to point out how multicast might be achieved, I never claimed it
would produce in sync video in every room. Such is hard to achieve.
There are two open source projects that I know of that have achieved
it:

>1. squeezebox .....
>2.  linuxmce .....

> The code base of these two projects may provide good clues on how to
get what you desire. After all the GPL allows this!
_______________________________________________

Also:
3. VLC.  I have already had VLC streaming via multicast. (Tested independent of Mythtv) Its easy to do and works well - I tested one 
VLC server and at least two clients using H.264 files and I think I did mpeg2 from memory also.  What I've next to do is add this 
into myth in some rough fashion.  (Shame I can't use VLC (just set it that is, presumably it could be coded in however I am not up 
to that at the moment...) as the player for recorded files - it could stream multicast as well)

There are various user models here.

Having multiple front ends start synchronised but maintain individual control with pause fast forward etc was not what I was 
seeking.  This seems to me to be closer to what we already enjoy, (and possibly more what ChrisXC is seeking?) with multiple 
independent frontends now able to function independently, the main issue in that case seems to be starting at the appropriate 
bookmark / place holder etc.

In more detail I am after a fully synchronised stream that the same thing happens to on all clients simultaneously, that seems 
functionally the same as Chris Pinkham's description, just it seems achieved different ways.  (Of course other frontends would also 
function independently while this is all happening)   In my case I could see one master and maybe four "followers" / slave clients 
which seems a lot of replicated LAN traffic.  Multicast seems to me more efficient - and scaleable.  I was just looking for that 
synchronisation for a start however remote control is the next issue, I was expecting that any remote control linked into that 
server would control things - e.g. pause would pause all the clients of that stream.  (It seems that might be relatively easy to do 
by telnetting into the master FE - and may be similar to the "switch" command suggested by Chris P?)  The ultimate RC I had in mind 
was a WiFi Cell Phone running a browser control app that could control the multicast server FE - from all rooms. The slave clients 
do not need to be mythTV, they can be VLC, or as Nick has already pointed out, the slave clients could be mplayer using vdpau.  Of 
course in the long run full integration within mythtv seems the preferable solution, I appreciate there may be quite a lot of 
patching to achieve that though.  I am just seeking to get a working model as a start.

Its also probably relevant to note that Chris Pinkham is very likely to be in a better position to advise the better method to 
achieve all this, however from his comments its not clear to me how much he considered multicast against the alternative outline he 
made.  Can you comment further Chris P?









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