Sending audio over bluetooth

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shawc01
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Joined: Wed Sep 30, 2009 1:57 am

Sending audio over bluetooth

Post by shawc01 » Wed Sep 30, 2009 2:02 am

Hi,

I want to send an audio stream over bluetooth to multiple recievers. Catch is I want to do this as cheap as possible.

I was wondering whether I can use a cheap bluetooth dongle connected to a USB enabled AVR and send the audio over bluetooth that way?

I won't go into too much more detail until someone can confirm whether this will be possible at all.

Cheers

MichaelN
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Location: Australia

Post by MichaelN » Wed Sep 30, 2009 2:36 am

Well, the USB AVR chips can operate in host mode, so in theory it would be possible. In practice, it might take a LOT of work to write the AVR drivers for the dongle, unless the protocol has been published or someone else has already figured out how to do it with that particular dongle.

I would have thought you'd be best to use a bluetooth module designed for embedded use, that has code already written you can use. Sparkfun has them starting from $35. There would be much cheaper options once you start talking about high volumes.

A $10 dongle won't seem such good value if you spend weeks or months trying to get it working.

Dutch2
Posts: 23
Joined: Sat Jan 27, 2007 1:46 pm

Post by Dutch2 » Wed Sep 30, 2009 5:08 am

The Bluegiga WT32 works great for audio. You can configure it through a simple serial port protocol so it's easy to connect to a micro.

Not sure about multiple connections... what mode do you want to use?

D2.

tz
Posts: 148
Joined: Sun Aug 23, 2009 10:40 pm

Post by tz » Sun Oct 25, 2009 5:53 pm

Non-USB bluetooth dongles tend to be expensive

There is a difference between one to 2-3, or to 10 or 100.

Bluetooth sound profiles are 1 to 1.

The headphone/handsfree and the A2DP are both computationally intensive (think MP3) - they don't just send an 8 bit sample stream.

So it probably is NOT possible, at least not knowing more details.

tz
Posts: 148
Joined: Sun Aug 23, 2009 10:40 pm

Post by tz » Mon Nov 02, 2009 12:01 am

There are two algorithms, one faster but (relatively) low quality for headsets HSP, and a high quality for music, A2DP. They are lossy compression much like MP3. The bluez stack for linux implements both (at least in beta) and it is open source.

It is NOT a voltage level. It is a set of frequencies put through a compressor.

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