SonixDecoder

Decode audio files (MP3, M4A, WAV, etc.) to raw PCM data for analysis and processing.

Quick Start

Kotlin

val audioData = SonixDecoder.decode("/path/to/audio.mp3")
if (audioData != null) {
    println("Sample rate: ${audioData.sampleRate}")
    println("Duration: ${audioData.durationMilliSecs}ms")
    println("Channels: ${audioData.numChannels}")

    val samples: FloatArray = audioData.samples
}

Swift

if let audioData = SonixDecoder.decode(path: "/path/to/audio.mp3") {
    print("Sample rate: \(audioData.sampleRate)")
    print("Duration: \(audioData.durationMilliSecs)ms")
    print("Channels: \(audioData.numChannels)")

    let samples: [Float] = audioData.samples
}

Methods

Method	Parameters	Returns	Description
decode	path: String, targetSampleRate: Int? = 16000	AudioRawData?	Decode with optional resampling
decodeNative	path: String	AudioRawData?	Decode at native sample rate

Resampling Behavior

The decode method resamples audio to the targetSampleRate by default:

// Default: resample to 16kHz (for Calibra APIs)
val calibraReady = SonixDecoder.decode("/path/to/audio.mp3")

// Explicit target rate
val at44k = SonixDecoder.decode("/path/to/audio.mp3", targetSampleRate = 44100)

// No resampling — keep native sample rate
val native = SonixDecoder.decode("/path/to/audio.mp3", targetSampleRate = null)

// Shorthand for no resampling
val native2 = SonixDecoder.decodeNative("/path/to/audio.mp3")

// Default: resample to 16kHz
let calibraReady = SonixDecoder.decode(path: "/path/to/audio.mp3")

// Explicit target rate
let at44k = SonixDecoder.decode(path: "/path/to/audio.mp3", targetSampleRate: 44100)

// No resampling
let native = SonixDecoder.decodeNative(path: "/path/to/audio.mp3")

AudioRawData

The decoded result contains:

Property	Type	Description
audioData	ByteArray	Raw PCM bytes (16-bit signed, little-endian)
samples	FloatArray / [Float]	Float samples in [-1.0, 1.0] range
sampleRate	Int	Sample rate in Hz
numChannels	Int	Number of channels (1 = mono, 2 = stereo)
durationMilliSecs	Int	Duration in milliseconds

Supported Formats

Format	Android	iOS
WAV	Yes	Yes
MP3	Yes	Yes
M4A/AAC	Yes	Yes
OGG	Yes	No
FLAC	Yes	Yes

Common Patterns

Decode for Analysis

val audioData = SonixDecoder.decode(filePath)  // 16kHz by default
if (audioData != null) {
    // Feed to Calibra for pitch detection
    val contour = pitchExtractor.extract(audioData)
}

Decode and Re-encode

val audioData = SonixDecoder.decode(inputPath, targetSampleRate = null)
if (audioData != null) {
    SonixEncoder.encode(data = audioData, outputPath = outputPath, format = "mp3")
}

Next Steps

• SonixEncoder — Encode PCM back to compressed formats
• SonixResampler — Explicit sample rate conversion
• SonixPlayer — Play audio files directly (no manual decoding needed)