Generate AVAudioPCMBuffer with AVAudioRecorder - swift

Question

Along with iOS 10, apple released a new framework which recognizes speech. Data can be passed to this framework either by appending AVAudioPCMBuffers or giving a URL to a m4a. Currently, speech recognition works using the former but this is only possible after somebody has finished and is not in real time. Here is the code for that:
let audioSession = AVAudioSession.sharedInstance()
var audioRecorder:AVAudioRecorder!;
var soundURLGlobal:URL!;
function setUp(){
let recordSettings = [AVSampleRateKey : NSNumber(value: Float(44100.0)),
AVFormatIDKey : NSNumber(value: Int32(kAudioFormatMPEG4AAC)),
AVNumberOfChannelsKey : NSNumber(value: 1),
AVEncoderAudioQualityKey : NSNumber(value: Int32(AVAudioQuality.medium.rawValue))]
let fileManager = FileManager.default()
let urls = fileManager.urlsForDirectory(.documentDirectory, inDomains: .userDomainMask)
let documentDirectory = urls[0] as NSURL
let soundURL = documentDirectory.appendingPathComponent("sound.m4a")
soundURLGlobal=soundURL;
do {
try audioSession.setCategory(AVAudioSessionCategoryPlayAndRecord)
try audioRecorder = AVAudioRecorder(url: soundURL!, settings: recordSettings)
audioRecorder.prepareToRecord()
} catch {}
}
function start(){
do {
try audioSession.setActive(true)
audioRecorder.record()
} catch {}
}
function stop(){
audioRecorder.stop()
let request=SFSpeechURLRecognitionRequest(url: soundURLGlobal!)
let recognizer=SFSpeechRecognizer();
recognizer?.recognitionTask(with: request, resultHandler: { (result, error) in
if(result!.isFinal){
print(result?.bestTranscription.formattedString)
}
})
}
I am trying to convert this but I cannot find where to get a AVAudioPCMBuffer.
Thanks,

Answer 1

good topic.
Hi B Person
here is topic with solution
Tap Mic Input Using AVAudioEngine in Swift
see lecture Wwdc 2014
502 - AVAudioEngine in Practice
capture microphone => in 20 min
create buffer with tap code => in 21 .50
here is swift 3 code
#IBAction func button01Pressed(_ sender: Any) {
let inputNode = audioEngine.inputNode
let bus = 0
inputNode?.installTap(onBus: bus, bufferSize: 2048, format: inputNode?.inputFormat(forBus: bus)) {
(buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in
var theLength = Int(buffer.frameLength)
print("theLength = \(theLength)")
var samplesAsDoubles:[Double] = []
for i in 0 ..< Int(buffer.frameLength)
{
var theSample = Double((buffer.floatChannelData?.pointee[i])!)
samplesAsDoubles.append( theSample )
}
print("samplesAsDoubles.count = \(samplesAsDoubles.count)")
}
audioEngine.prepare()
try! audioEngine.start()
}
to stop audio
func stopAudio()
{
let inputNode = audioEngine.inputNode
let bus = 0
inputNode?.removeTap(onBus: bus)
self.audioEngine.stop()
}