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I am developing a custom hardware (peripheral) device that will communicate with Android smartphones through BLE. This device will have several capabilities, including the transmission of audio through GATT and keypresses through HID.

Is it somehow possible to re-route the BLE audio input to the Android OS if it was the internal device microphone? For instance, so that we could make voice searches using the default Google app, using the microphone on this external device. Can it be done without rooting the device, writing custom drivers or customize the kernel?

I found several similar threads on SO, but none with a specific solution for this issue (e.g., An extensive project: Streaming audio from microphone to Android device)

Thanks in advance!

Sagito
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1 Answers1

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It can be done. This is how I did it:

  1. Have a service that talks to BLE Remote device and receives audio
  2. Create a Audio HAL that implements an audio input.
  3. Modify Audio Policy manager to use your HAL for Voice-recognition inputs
  4. Send audio data from Service to HAL over any available IPC (I use socket)

Done.

There are other ways too. e.g. you could allow regular pairing but then intercept all audio messages from your device in fluoride and forward them to your, or A2DP HAL etc.

GPS
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