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Multiple Bluetooth speakers from one minijack
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Multiple Bluetooth speakers from one minijack

by maer on Fri Jul 24, 2020 1:06 pm

I have an idea to use feather bluefruit or circuit playground bluefuit to create a device that would allow one audio input to be played on many (4?) Bluetooth speakers simultaneously. I have been trying to do this on the cheap with Echo dot / flex and its just not smooth. Smarter solutions / opinions welcome. FYI I have iPhone not android, and I don't want to pay 9.99 x 5 phones for apps..

So the questions is, what is the lowest cost way to get this done? Rasberry Pi would be a reach for me knowledge-wise, arduino is more my speed.

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Re: Multiple Bluetooth speakers from one minijack

by adafruit_support_mike on Sun Jul 26, 2020 4:05 am

Unfortunately, Bluetooth audio is a hacker-unfriendly system.

For starters, 'Bluetooth' is a blanket name for a collection of mostly-incompatible wireless protocols that happen to be managed by the same working group. The hacker-friendly version is the Low Energy variant (BLE), but that isn't fast enough to carry real-time audio, even using compression.

All the Bluetooth speakers I know of use the Classic version, which is fast enough to transmit MP3s, but comes with a bunch of hacker-unfriendly conditions. For one, all BT-C devices have to implement one of the published device profiles exactly. That makes life easier for OS developers, but leaves almost zero room for experimentation & modification. Worse, all BT-C devices have to transmit a Vendor ID code, which you can only get by paying the BT Working Group several thousand dollars.

The basic structure of the Bluetooth protocols also works against the concept of multiplexing. The basic design goal for Bluetooth was to provide a wireless replacement for USB cables, so the whole protocol is built around the concept of a central computer talking to a collection of independent peripheral devices. Ideas like peripherals talking to each other, or the central device sending the same information to multiple peripherals, just aren't part of the model.

You'd probably have more luck using an off-the-shelf bluetooth speaker as your main device, then broadcasting the data it receives using another protocol like Wifi. TCP/IP at least has the basic concept of multicast communication.

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