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  #1  
Old 10-26-2012, 05:27 PM
lifeofbirds lifeofbirds is offline
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Default Synchronizing playback on multiple mp3 players

Hello all,

I am working on a project where I need to synchronize playback on 30 mp3 players. Each mp3 player will have a unique track that is 30 mins long, and I need to be able to hit play on all of them at the exact same time so they are playing back in synch. I actually did this a few years ago using ipod nanos and a third party remote system called ijet -

http://www.buyijet.com/top-products/...re-remote.html

I purchased 30 of these ijets and connected them to 30 ipod nanos and synched all the ijets to one remote. When I hit play all 30 nanos would start at the same time. The problem was, that they didn't start at exactly the same time (probably about a 500ms lag between them) AND sometimes one or two wouldn't trigger and they I would have to manually stop them all, and try to synch again...it was pretty hit and miss.

I no longer have the ipod nanos - they were kept by the institution that originally funded the project. And now I am gearing up to do the piece again and I want to figure out a better way to synch start some mp3 players - no lag would be ideal. It doesn't matter which mp3 player I use, or if they are remote started, or can all be hooked up to a micro-controller that starts them. Always better to keep the budget low if possible.

An entirely different route I was thinking about would be 30 wireless in ear monitors, receiving audio from a multichannel DAC, but the costs of that would be astronomical, so mp3 players seem like the way to go.

Any suggestions?
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  #2  
Old 10-26-2012, 06:29 PM
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Brett_val Brett_val is offline
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If sync is important why not use one source, and connect it to some amp setup that can support 30 headphones? If it can be wired with long cables it may be cheaper as well.
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  #3  
Old 10-29-2012, 09:28 AM
lifeofbirds lifeofbirds is offline
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I want to completely avoid cables so that the performers are able to move around a large space.

I need 30 unique tracks going to 30 headphones. The performers are listening to the headphones to receive instructions, so I don't want them wired to anything (thus mp3s or wireless of some sort). And the clincher is...I want all 30 tracks to start simultaneously and be in sync....
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Old 10-29-2012, 12:14 PM
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Mo. FryDaddy Mo. FryDaddy is offline
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I don't think you'll be able to accomplish this cheaply, as your requirements are very specific and your usage of mp3 players out of the ordinary.

That being said one of the only options I can think of that might possibly work (and this is a big if) is to talk to the guys over at Rock Box http://www.rockbox.org/ and see if they have a firmware and player that supports remote start so you could have 30 Sansa clips for example connected to the computer to start the track and then disconnect them for your deal.

But IMO the wireless option is the way to go that way it is all controlled from a single source rather than 30 independent sources.
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Old 10-30-2012, 04:06 PM
lifeofbirds lifeofbirds is offline
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Wireless would be ideal, but I'm afraid the costs are pretty ridiculous.

Thanks for the tip on rocksbox. I will hit them up and see if it is possible.
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Old 10-31-2012, 07:51 AM
CDMP3PlayerFan CDMP3PlayerFan is offline
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Would setting up all of the players to begin playing at a specific time be a possiblity?
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Old 10-31-2012, 12:44 PM
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Mo. FryDaddy Mo. FryDaddy is offline
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That is a thought, I know my Zen micro (back in the day) could be set to play a song at a specific time as an alarm. But I wonder if that would be exact enough? Since he was saying about having problems with 500ms lag.
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Old 10-31-2012, 09:50 PM
saratoga saratoga is offline
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You need some instantaneous way to distribute a clock or trigger signal. This probably can be done over WiFi with only modest timing jitter or over a hacked player remote or maybe custom software monitoring a microphone. Either way its going to be some combination of very difficult and expensive.
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