Microphone input to speakers output in iOS?

Question

How can I hear on the speaker the same thing that the microphone records but live?

What I want to do is to have my earphones on and hear the same thing but I will just manage the volume.

I know how to record the audio and then play it but I want it to be live, I don't need to save the audio, just hear the same thing at the same time.

I just see that AurioTouch do that but it also does a lot more so I don't really understand it cause I don't know what I need from that big project — Luis Felipe, Oct 26 '15 at 21:43

score 4 · Answer 1 · edited Feb 08 '22 at 18:39

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I know this question is ancient, but I was recently trying to do this and I found that the easiest way to do this is to use the AVAudioEngine. Once you instantiate it it has an inputNode property that represents the mic and an outputNode property that represents the speakers. You connect the input node to the output node like this:

engine.connect(engine.inputNode, to: engine.outputNode, format: engine.inputNode.inputFormat(forBus: 0))
engine.start()

edited Feb 08 '22 at 18:39

Geri Borbás

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answered Jul 20 '20 at 03:26

derickito

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Underrated answer, this piece of code works out of the box! I replaced a whole lot of `AVCaptureSession` buffer stream magic with this nicely. – Geri Borbás Feb 04 '22 at 20:00
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Helped a lot creating this live audio solution: https://stackoverflow.com/questions/71006555/route-live-audio-from-line-in-to-airpods – Geri Borbás Feb 08 '22 at 18:37
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Awesome, glad this could help – derickito Feb 10 '22 at 19:42

score 0 · Answer 2 · answered Oct 28 '15 at 18:20

You can't get live output, as the iOS audio system buffers audio sample both in and out. But you can often get a latency below 12 milliseconds by using the RemoteIO Audio Unit API after requesting a very short (5 mS) audio buffers in the app's AVAudioSession initialization options.

If you want minimum latency (as close to live as possible) then you will have to understand and use the slightly more complex lower level audio APIs, as the easy high level APIs are slower (usually due to longer buffering).

Do you know where I can fin how to use RemoteIO Audio Unit API with swift? or at least with obj-c :) — Luis Felipe, Oct 30 '15 at 00:20

score 0 · Answer 3 · answered Mar 18 '21 at 03:01

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If you just want a ready-made app that does this, download the free Speech Jammer app and disable the audio delay.

answered Mar 18 '21 at 03:01

pbiddle1965

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Microphone input to speakers output in iOS?

3 Answers3