Sonix
Decodes audio files to raw PCM data.
What is Audio Decoding?
Audio files (MP3, M4A, etc.) are compressed - they store audio efficiently but can't be processed directly. Decoding converts compressed audio to raw PCM samples that Calibra APIs can analyze.
When to Use
| Scenario | Use This? | Why |
|---|---|---|
| Load audio file for pitch detection | Yes | Calibra needs raw PCM |
| Load audio for melody evaluation | Yes | Core use case |
| Play audio file | No | Use SonixPlayer (decodes internally) |
| Record audio | No | Use SonixRecorder |
Quick Start
Kotlin
// Decode to 16kHz (default) for use with Calibra
val audioData = SonixDecoder.decode("/path/to/audio.mp3")
if (audioData != null) {
println("Sample rate: ${audioData.sampleRate}") // Always 16000
println("Channels: ${audioData.numChannels}")
println("Duration: ${audioData.durationMilliSecs}ms")
// Use with Calibra APIs (expects 16kHz)
val samples = audioData.samples
}
// Decode at native sample rate (no resampling)
val nativeAudio = SonixDecoder.decode("/path/to/audio.mp3", targetSampleRate = null)Swift
// Decode to 16kHz (default) for use with Calibra
if let audioData = SonixDecoder.decode(path: "/path/to/audio.mp3", targetSampleRate: 16000) {
print("Sample rate: \(audioData.sampleRate)") // Always 16000
print("Channels: \(audioData.numChannels)")
print("Duration: \(audioData.durationMilliSecs)ms")
// Use with Calibra APIs
let samples = audioData.samples
}
// Decode at native sample rate
let nativeAudio = SonixDecoder.decodeNative(path: "/path/to/audio.mp3")Supported Formats
| Format | Android | iOS |
|---|---|---|
| WAV | Yes | Yes |
| MP3 | Yes | Yes |
| M4A/AAC | Yes | Yes |
| OGG | Yes | No |
| FLAC | Yes | Yes |
Platform Notes
iOS
Uses AVFoundation for hardware-accelerated decoding
Supports any format supported by Core Audio
Android
Uses MediaExtractor and MediaCodec for hardware decoding
Falls back to software decoding if needed
Common Pitfalls
Null return: Check for null - decoding fails if file doesn't exist or format unsupported
Wrong sample rate for Calibra: Use default (16kHz) or explicitly set targetSampleRate=16000
Memory for large files: Decoding loads entire audio into memory
Relative paths: Use absolute file paths
See also
For the decoded audio data structure
For encoding raw audio back to compressed formats
For explicit resampling control
For analyzing decoded audio