audio_decoder #

A lightweight Flutter plugin for converting, trimming, and analyzing audio files using native platform APIs. No FFmpeg dependency required.

Features #

• Convert MP3, M4A, AAC, FLAC, OGG, WMA, AIFF, and more to WAV
• Convert any audio format to M4A (AAC) — compressed output
• Get audio metadata (duration, sample rate, channels, bit rate, format)
• Trim audio files to a specific time range
• Extract waveform amplitude data for visualization
• Uses native platform APIs — no bundled codecs or heavy dependencies
• Supports Android, iOS, macOS, and Windows
• Minimal app size impact (~500KB vs ~15-30MB for FFmpeg)

Platform APIs #

Getting started #

Add audio_decoder to your pubspec.yaml:

dependencies:
  audio_decoder: ^0.1.0

Or install via the command line:

flutter pub add audio_decoder

No additional setup is needed — the plugin uses built-in platform APIs.

Usage #

import 'package:audio_decoder/audio_decoder.dart';

// Convert to WAV (lossless)
final wavPath = await AudioDecoder.convertToWav(
  '/path/to/song.mp3',
  '/path/to/output.wav',
);

// Convert to M4A (AAC compressed)
final m4aPath = await AudioDecoder.convertToM4a(
  '/path/to/song.wav',
  '/path/to/output.m4a',
);

// Check if a file needs conversion
if (AudioDecoder.needsConversion('song.mp3')) {
  // ...
}

Get audio info #

final info = await AudioDecoder.getAudioInfo('/path/to/song.mp3');
print(info.duration);   // Duration(seconds: 183)
print(info.sampleRate); // 44100
print(info.channels);   // 2
print(info.bitRate);    // 320000
print(info.format);     // "mp3"

Trim audio #

// Trim to a specific time range — output format is based on file extension
final trimmed = await AudioDecoder.trimAudio(
  '/path/to/song.mp3',
  '/path/to/clip.wav',         // .wav or .m4a
  Duration(seconds: 10),       // start
  Duration(seconds: 30),       // end
);

Get waveform #

// Extract normalized amplitude data (0.0–1.0) for visualization
final waveform = await AudioDecoder.getWaveform(
  '/path/to/song.mp3',
  numberOfSamples: 100,
);
// waveform = [0.12, 0.45, 0.87, 0.23, ...]

Error handling #

try {
  await AudioDecoder.convertToWav(inputPath, outputPath);
} on AudioConversionException catch (e) {
  print('Conversion failed: ${e.message}');
}

Supported formats #

The needsConversion helper recognizes these extensions:

.mp3 .m4a .aac .mp4 .ogg .oga .opus .flac .wma .aiff .aif .amr .caf .alac .webm

The native decoders may support additional formats. You can always call convertToWav directly on any file — it will throw an AudioConversionException if the platform cannot decode it.

Output formats #

WAV #

• PCM signed 16-bit little-endian
• Original sample rate and channel count preserved
• Standard 44-byte RIFF/WAVE header

M4A #

• AAC-LC encoding at 128 kbps
• Original sample rate and channel count preserved
• MPEG-4 container

Platform requirements #

License #

See LICENSE for details.