How do you do bicubic (or other non-linear) interpolation of re-sampled audio data?

My favorite resource for audio interpolating (especially in resampling applications) is Olli Niemitalo’s “Elephant” paper. I’ve used a couple of these and they sound terrific (much better than a straight cubic solution, which is relatively noisy). There are spline forms, Hermite forms, Watte, parabolic, etc. And they are discussed from an audio point-of-view. This is … Read more

Recording audio in Swift

In Swift 3 Add framework AVFoundation **In info.plist add key value Key = Privacy – Microphone Usage Description and Value = For using microphone (the apps will crash if you don’t provide the value – description why you are asking for the permission)** Import AVFoundation & AVAudioRecorderDelegate, AVAudioPlayerDelegate import AVFoundation class RecordVC: UIViewController , AVAudioRecorderDelegate, … Read more

Note onset detection

Here is a graphic that illustrates the threshold approach to note onset detection: This image shows a typical WAV file with three discrete notes played in succession. The red line represents a chosen signal threshold, and the blue lines represent note start positions returned by a simple algorithm that marks a start when the signal … Read more