Применяя ИК-фильтр, дополнительный шум при произнесении появляется в звуке сердцебиения. ⇐ IOS

[Гость]

In my iOS application, using swift

i am getting audio from digital health device (BLE). In the form of audio data, to hear heart beats.

• We apply ADPCM decoder on received data. When playing it has background noise with heart beats.
• To filter that, we apply filter to remove background noise. It is band pass IIR filter.

IIR Parameters for frequency 20 - 200 Hz

B 0.3468218078469383,0.0,-1.3872872313877531,0.0,2.0809308470816297,0.0,-1.3872872313877531,0.0,0.346821807846938

A 1.0,-0.692931448722861,-1.7554648142444358,0.7966332180729667,1.6060001719379677,-0.4353468784755548,-0.691339842239745,0.08285290618602029,0.12038959989624454

Below is a Filter code

Код: Выделить всё

func applyFilterToData(decoded: Data) -> Data {         // Example usage             var lastData = Data()         for decodedData in decoded {             let unsignedData = UInt8(decodedData)             let lowPassUInt8 = iirFilterNew.filter(Double(unsignedData))             lastData.append(lowPassUInt8)             filteredDataToShare.append(lastData)             self.n = (self.n + 1) % 9         }         // Receive UInt8 -> Data         return lastData     } func filter(_ input: Double) -> UInt8 {         // Update input history         xHistory.insert(input, at: 0)         xHistory.removeLast()                  // Calculate output         var output = b[0] * xHistory[0]                  for i in 1.. 127.0 {             val = 127.0         }         if val < -128.0 {             val = -128.0         }         var signedInt: Int8 = 0         if val.isNaN {             signedInt = 0         } else {             signedInt = Int8(val)         }         return UInt8.init(bitPattern: Int8(signedInt))     } 

Below are Audio samples to filter:

https://drive.google.com/file/d/1qV8YBF ... sp=sharing


Источник: https://stackoverflow.com/questions/780 ... beat-sound