[mythtvnz] DVB multicasting

[Nick Rout]

On Tue, Oct 27, 2009 at 11:01 PM, Tortise <tortise at paradise.net.nz> wrote:
> ----- 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 10:03 PM
> Subject: Re: [mythtvnz] DVB multicasting
>
> There is no provision for synchronised viewing. However if we all want
> to watch top gear live then you set it to record on the backend. Any
> numbber of frontends can watch that recording, live or within a few
> seconds of live. (Why you would want to, and have to sit thru the ads
> is another point)
>
> => Apologies Nick for not being clear, I agree I have no issue with Live TV, it can be watched....live!   I was really referring to
> simultaneous synchronised multicast playback of recordings, +/- commercial deletions.
>
> (Have tried re-enabling the "<", the Gates derived ware will not add them back in! Perhaps a reboot will re-enable it in due
> course!)
>
>

get a new mailer. how anyone can seriously want to use OE is beyond
me. Please fix whatever is wrong as you are clearly pissing more than
one person off.

>
>> 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?
>>
>
> I send a signal out multicast. To all intents and purposes each system
> on my lan gets it simultaneously. However each machine has different
> hardware. There could easily be a delay that is annoying, in that
> there will be an "echo" in the sound. A few milliseconds can be
> enough.
>
> => I agree this might be an issue if those different pc speakers were in the same room, but then depending where one sat it would be
> an issue anyway.  Would it be an issue for echo between rooms?  The volume in another room would need to be high enough to be heard
> in the adjacent room.  Is that the potential echo you are referring to Nick, I'd not see that as a concern.

If there is no audio connection between the rooms, why do you need to
synchronise? Why not just let everyone watch independently?

> (Or are you suggesting
> an echo is returned over ethernet?  Not to my expectation using multicast udp.)
>

No I am talking about the different delays inherent in the signal
processing inside each front end leading to unsynchronised sound,
which will _sound_ like an echo.

> Given we have not done the proposed multicast synchronisation it seems the echo problem is derived in no more than informed
> prediction.  What is the echo path you predict?
>
>> You can try it now with the OP's setup suggestion. Let us know the result.
>
> I'm interested.  What's the "OP setup suggestion"?
>

I'll be plainer: If you want to try multicast, try the Original
Poster's setup and let us know the results.