[mythtv-users] Synchronising frontends

Andre mythtv-list at dinkum.org.uk
Mon Nov 15 11:26:54 UTC 2010


On 15 Nov 2010, at 10:55, Russell Gower wrote:

> Hi,
>  I'm currently running a 0.23 system on Debian Lenny (will upgrade when 0.24 packages become available) using separate front and backend servers. My Frontend netboots from the backend with a NFS root filesystem and is connected via HDMI to my lcd TV in the lounge for video and a spdif cable to my amp for audio. 
> 
> I would like to add a slave system in the kitchen, so that we can watch TV whilst cooking etc, I'm currently investigating my options - The key requirement  is that playback should be synchronised with the existing front end!

The only way you will get synchronised audio is by feeding the same already decoded audio to both locations, e.g feed pcm stereo to both via spdif, ac3 passthough can be out of sync when using different decoders!

Alternatively most surround amps have an analog second zone output, this will be guaranteed to be in sync as it's coming from the same amp. I'm assuming the amp in the living room will be on otherwise who cares about sync.

 Of course it's highly likely that the LCD in the kitchen will have a different delay to the one in the living room even if fed from split HDMI, so video won't be in sync with audio! It's going to be one of those pick any two from three issues.

In my experience even slight audio differences are extremely noticeable and annoying, especially if they change over time which any streamed and almost all digital solutions will do. The ONLY guaranteed properly in sync solution will be completely analog, amp second zone, parallel speakers or similar.

Andre


> 
> This is what I've come up with so far
> 	1. New frontend system 
> 		Pros
> 			Simpler cabling (cat already in place)
> 			Would be useful to have electronic cookery books/recipes 
> 		Cons
> 			Additional computer required
> 			Unsure if synchronisation is posible 
> 
> 	2. Use a HDMI splitter to split the video signal to the second TV
> 		Pros
> 			Doesn't require an additional computer
> 		Cons
> 			Cabling will be harder although not impossible
> 			Audio will be an issue - need to supply down mixed audio not sure how
> 			Second tv will have a different native resolution (are small tv's/monitors available that will take a 1920x1080 input)
> 
> 	3. Use second video output from existing front end's video card
> 		Pros
> 			Doesn't require an additional computer
> 		Cons
> 			Is it possible to output the same video in two different resolutions simultaneously?
> 			Audio will be an issue - need to supply down mixed audio not sure how
> 
> 
> Has anyone done anything similar? Any comments? Have I missed a better solution?
> 
> Thanks
> Rrussell
> 
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