Reply To: OE and Bluetooth HFP 8kHz Audio signal

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August 2, 2016 at 8:18 pm #1030771
tbrandt78
Participant

Hey Halle –

So, it seems that none of these settings will help my case, as far as I can tell. These settings all affect how OEContinuousAudioUnit::setAllAudioSessionSettings sets the AVAudioSession.

From what I can tell, disablePreferredSampleRate just stop OE from attempting to override the sample rate using this AVAudioSession command :
[AVAudioSession sharedInstance].preferredSampleRate

The issue that I have observed from the automotive BluetoothHFP systems is that the audio input all seems to be 8kHz. I have already tried to set preferredSampleRate to 16000, but it always results in the sample rate staying at 8kHz.

So… I really believe that the answer here is to ‘up-sample’ the input audio signal when 8kHz to 16kHz for OpenEars to take, cleanly. Yes, the captured audio will still have 8kHz resolution, but the bit depth will be at 16kHz which seems more compatible for OpenEars.

Thoughts?