How can I generate an array of floats from an audio file in Swift
Above answers didn't work for me, I'm using Swift5, found this extensions that worked for me here: https://gist.github.com/jtodaone/f2fa59c19794811dbe989dff65a772bc
Also here is how i use the code on Playground
import UIKit
import AVFoundation
let filePath: String = Bundle.main.path(forResource: "nameOfFile", ofType: "wav")!
print("\(filePath)")
let fileURL: NSURL = NSURL(fileURLWithPath: filePath)
let audioFile = try AVAudioFile(forReading: fileURL as URL)
let audioFormat = audioFile.processingFormat
let audioFrameCount = UInt32(audioFile.length)
let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: audioFrameCount)
try audioFile.read(into: audioFileBuffer!)
extension AudioBuffer {
func array() -> [Float] {
return Array(UnsafeBufferPointer(self))
}
}
extension AVAudioPCMBuffer {
func array() -> [Float] {
return self.audioBufferList.pointee.mBuffers.array()
}
}
extension Array where Element: FloatingPoint {
mutating func buffer() -> AudioBuffer {
return AudioBuffer(mNumberChannels: 1, mDataByteSize: UInt32(self.count * MemoryLayout<Element>.size), mData: &self)
}
}
let array = audioFileBuffer?.array()
print(array?.count) //Optional(2705408)
It's really tricky to find everything about UnsafeBufferPointer
Here I am posting updated code for Swift 5.0
if let url = Bundle.main.url(forResource: "silence", withExtension: "mp3") {
let file = try! AVAudioFile(forReading: url)
if let format = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: file.fileFormat.sampleRate, channels: 1, interleaved: false) {
if let buf = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 1024) {
try! file.read(into: buf)
// this makes a copy, you might not want that
let floatArray = UnsafeBufferPointer(start: buf.floatChannelData![0], count:Int(buf.frameLength))
// convert to data
var data = Data()
for buf in floatArray {
data.append(withUnsafeBytes(of: buf) { Data($0) })
}
// use the data if required.
}
}
}
Hope it will help you :)
I have updated the code from @rhythmicfistman to Swift5
. There were about a dozen changes to make: apparently things changed dramatically in swift
world.
func readWavIntoFloats(fname: String, ext: String) -> [Float] {
let url = Bundle.main.url(forResource: fname, withExtension: ext)
let file = try! AVAudioFile(forReading: url!)
let format = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: file.fileFormat.sampleRate, channels: 1, interleaved: false) ?? <#default value#>
let buf = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 1024)!
try! file.read(into: buf)
// this makes a copy, you might not want that
let floatArray = Array(UnsafeBufferPointer(start: buf.floatChannelData?[0], count:Int(buf.frameLength)))
return floatArray
}
AVAudioFile
built-in to iOS (and OS X), is very convenient and will also do format conversions for you:
import AVFoundation
// ...
let url = NSBundle.mainBundle().URLForResource("your audio file", withExtension: "wav")
let file = try! AVAudioFile(forReading: url!)
let format = AVAudioFormat(commonFormat: .PCMFormatFloat32, sampleRate: file.fileFormat.sampleRate, channels: 1, interleaved: false)
let buf = AVAudioPCMBuffer(PCMFormat: format, frameCapacity: 1024)
try! file.readIntoBuffer(buf)
// this makes a copy, you might not want that
let floatArray = Array(UnsafeBufferPointer(start: buf.floatChannelData[0], count:Int(buf.frameLength)))
print("floatArray \(floatArray)\n")
Sadly, for doubles it doesn't seem to be enough to substitute .PCMFormatFloat32
with .PCMFormatFloat64
because AVAudioPCMBuffer
doesn't have a float64ChannelData
method.
update because I don't know swift well
You can avoid copying the array by working with the UnsafeBufferPointer
, which is a perfectly good collection type:
let floatArray = UnsafeBufferPointer(start: buf.floatChannelData[0], count:Int(buf.frameLength))