Reply To: OE and Bluetooth HFP 8kHz Audio signal

Home Forums OpenEars OE and Bluetooth HFP 8kHz Audio signal Reply To: OE and Bluetooth HFP 8kHz Audio signal


Thanks Halle for the quick reply like always. I’ve already written the AVAsset routines to downsample the SaveThatWave output to 8k but I was hoping to not need them.
I didn’t think it would be that big a deal for you to retain the Openears sampling rate through SaveThatWave – I didn’t think you would need to – or should, cater for any variations – simply prevent SaveThatWave from upsampling.
I don’t at all like the loss of fidelity with Openears sampling at 8kHz, SaveThatWave upsampling to 16kHz, then AVAsset downsampling to 8kHz.

My cloud recognition accuracy was extremely low when I was sending 16kHz wav files that contained 8khz bluetooth audio. Recognition rates were better after downsampling the files to 8kHz but nowhere near as good as when I record the audio myself at 8kHz with AVAudioSession

Also – just in case you didn’t know, this 8khz mode should not be applied to all bluetooth connections. Bluetooth HFP 1.6 supports “wideband audio” aka “HD audio” which is sampled at 16kHz. HFP 1.6 was specced around 2012. If both sides support HFP 1.6 or 1.7, then a 16kHz recording should be used.