Audio Streaming
Learn how to stream and buffer audio data
Overview
flutter_soloud supports streaming audio data while receiving it in real-time. The supported audio data formats are raw PCM or compressed through the Opus and Ogg libraries from Xiph.org. This is particularly useful when:
- Streaming audio from network sources
- Generating audio data on-the-fly
- Processing audio in chunks
- Working with OpenAI or other streaming APIs
The Opus and Ogg libraries are embedded by default in flutter_soloud. However, if you don't need streaming capabilities, please read the Without Opus/Ogg section for how to exclude these libraries from your app.
Buffer Stream Setup
Initialize an audio stream:
final stream = SoLoud.instance.setBufferStream(
maxBufferSizeBytes: 1024 * 1024 * 10, // 10MB of max buffer (not allocated)
bufferingType: BufferingType.preserved,
bufferingTimeNeeds: 2.0, // 2 seconds buffer
sampleRate: 44100,
channels: Channels.stereo,
format: BufferType.s16le,
);
Preserved Mode
final stream = await SoLoud.instance.setBufferStream(
bufferingType: BufferingType.preserved,
// ...other parameters
);
- Keeps all audio data in memory
- Allows multiple playback instances
- Supports seeking and looping
- Higher memory usage
Released Mode
final stream = await SoLoud.instance.setBufferStream(
bufferingType: BufferingType.released,
// ...other parameters
);
- Frees played audio data
- Single playback instance only
- Lower memory usage
- Must be manually disposed
Supported Formats
s8- Signed 8-bit PCMs16le- Signed 16-bit PCM (little endian)s32le- Signed 32-bit PCM (little endian)f32le- 32-bit float PCM (little endian)opus- Opus codec with Ogg container
Adding Audio Data
// Add audio data to the stream
SoLoud.instance.addAudioDataStream(
stream,
audioChunk, // Uint8List of audio data
);
// Mark the stream as complete
SoLoud.instance.setDataIsEnded(stream);
Buffer Management
// Get current buffer size
final size = SoLoud.instance.getBufferSize(stream);
// Reset the buffer
SoLoud.instance.resetBufferStream(stream);
Example: Network Streaming
// Create a WebSocket connection
final socket = await WebSocket.connect('wss://audio-stream.example.com');
// Set up the audio stream
final stream = SoLoud.instance.setBufferStream(
bufferingType: BufferingType.released,
format: BufferType.opus,
onBuffering: (isBuffering, handle, time) {
// When isBuffering==true, the stream is set to paused automatically till
// it reaches bufferingTimeNeeds of audio data or until setDataIsEnded is called
// or maxBufferSizeBytes is reached. When isBuffering==false, the playback stream
// is resumed.
print('Buffering: $isBuffering, Time: $time');
},
);
// Start playback
final handle = await SoLoud.instance.play(stream);
// Listen for audio data
socket.listen((data) {
if (data is List<int>) {
SoLoud.instance.addAudioDataStream(
stream,
Uint8List.fromList(data),
);
}
});
Example: PCM Generation
@pragma('vm:entry-point')
Future<AudioSource> generatePCM() async {
final pcmStream = SoLoud.instance.setBufferStream(
maxBufferSizeBytes: 1024 * 1024,
format: BufferType.s16le,
channels: Channels.mono,
sampleRate: 44100,
);
// Generate some PCM data
final buffer = Int16List(44100);
for (var i = 0; i < buffer.length; i++) {
buffer[i] = (sin(2 * pi * 440 * i / 44100) * 32767).toInt();
}
// Add to stream
SoLoud.instance.addAudioDataStream(
pcmStream,
buffer.buffer.asUint8List(),
);
SoLoud.instance.setDataIsEnded(pcmStream);
return pcmStream;
}