Playback streaming audio with AVAudioengine (iOS)

user_8669186 0
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I want to stream audio on iOS using AVAudioEngine. Currently I'm not sure how to do this.

I get RTP data from the network and want to playback this audio data with AVAudioEngine.

I am using the iOS Network.Framework to receive the network data. I then decode the speech data and now want to play it back using AVAudioEngine.

Here is my receive code: 

connection.receiveMessage { (data, context, isComplete, error) in
    if isComplete {

    // decode the raw network data with Audio codec G711/G722
    let decodedData = AudioDecoder.decode(enc: data, frames: 160)

    // create PCMBuffer for audio data for playback
    let format = AVAudioFormat(standardFormatWithSampleRate: 8000, channels: 1)
    let buffer = AVAudioPCMBuffer(pcmFormat: format!, frameCapacity: 160)!
    buffer.frameLength = buffer.frameCapacity

    // TODO: now I have to copy the decodedData --> buffer (AVAudioPCMBuffer)

    if error == nil {
       // recall receive() for next message
       self.receive(on: connection)
    }
}

How do I copy the decodedData to my AVAudioPCMBuffer? Currently, my buffer var is created, but does not contain any data.

Background information:

My general approach would be to cache inside the PCMBuffer with a collection and playback this collection with the AVAudioEngine.

Is there a better way consume the audio data directly (instantly)?

avaudioengine playback audio streaming ios
2 Answers

Not sure if you've found a solution yet, but I was able to stream audio with AVAudioEngine. I didn't use AudioDecoder but instead streamed packets using URLSession to download packets. Then I streamed these downloaded packets into AudioFileStreamOpen where I formatted audio packets. Finally, I converted these packets into PCM buffers for the engine using AudioConverterFillComplexBuffer and scheduled these buffers into the engine for playback.

Here's my completed project: https://github.com/tanhakabir/SwiftAudioPlayer in which I set up a full engine that I used on my podcast player. And here's a short blog I wrote about the overall architecture: https://medium.com/chameleon-podcast/creating-an-advanced-streaming-audio-engine-for-ios-9fbc7aef4115

Here's the blog I based my library on: https://github.com/syedhali/AudioStreamer

user_72604850

try AVAudioConverter

let converter = AVAudioConverter(from: inputFormat, to: outputFormat)

user_5662060
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