[mythtv-users] simultaneous viewing

[James Linder]

On 13/04/2012, at 4:09 AM, mythtv-users-request at mythtv.org wrote:

>>>> Ideally I would like two new features to mythfrontend, 1. add functionality to broadcast a playback timestamp for the currently playing file. 2. add functionality to allow "slave" frontends to optionally synchronise to this timestamp (with a configurable varience to allow for syncing audio). The first should be fairly easy, I'm not sure about the second. I would be willing to have a stab at implementing this if it where likely to be accepted by the devs.
>>> Damn, should have read the whole thread first, apologies.  I think any reasonable dev is unlikely to accept that proposition. The app needs to be written and tested, I think it would work, however I think one can only expect the dev's to consider something concrete.  Similarly using the frontend network interface its possible (I think) to write something that can be independent of the code, so long as it complies with the protocols it could remain independent of the code.  I think that something tested and working for a number of people is likely to get a favourable hearing from the dev's, but I can't expect them to commit to anything before they see it.
>>> 
>>> An obvious issue to me is how many frontends will be coordinated slaves and how will they be controlled in the various combinations?
>> Agreed, I wouldn't expect anything to be accepted until well proven, what I would be looking for is agreement that a well implemented solution would be considered rather than turned down point blank.
>> 
>> I'm not sure how an external application could provided the required timing for near frame accurate synchronisation.
>> 
>> I've not done any real design work yet, but my initial thoughts are that a frontend operating normally would use ip multicasting to announce it's name the file name of the currently playing recording and its current position within the file, this would take place every couple of seconds.
>> 
>> All frontends would listen for the multicast's and provide a play back option for each of them, once playing they would use the time stamp portion of the multicast to remain synchronised.
>> 
> 
> During playback, timing will drift from "absolute" independently on 
> different systems depending on what's happening.  Therefore, you would 
> need an very-well-designed approach for synchronizing playback on 
> multiple devices, including a protocol for control and a protocol for 
> playback sync.

[snip]

... and I pause my playback ... and havoc engulfs the multicast users (or worse pause has no effect)

James