Flutter_sound Recorder

[Stimm4]

Hi,

I start to Flutter, but I need to record a sound with a specific bufferSize.

Using the example, this doesn't work for me.

Is it possibl to specify a bufferSize ?

Thanks

[Larpoux]

Which platform? Web, iOS or Android?
Which tool ? Recorder or player ?
Files, buffers, uri or streams?

[Stimm4]

I use it in Android for now, and I tried to set the BufferSize like this :

`Future _startRecording() async {
if (await Permission.microphone.request().isGranted) {
setState(() {
_isRecording = true;
});

    _recorder!.startRecorder(
      codec: Codec.pcm16,
      toStream: _audioStreamController.sink,
      bufferSize : 100, // This doesn't work
        bitRate : 8000

    );

    _audioStreamController.stream.listen((buffer) {
      _processBuffer(buffer);
    });
  } else {
    print('Microphone permission not granted');
  }
}

void _processBuffer(Uint8List buffer) {
  // Convert the Uint8List to Int16List if necessary and pass it to native code
  final Int16List int16Buffer = Int16List.view(buffer.buffer);
  _audioProcessor.processAudio(int16Buffer);
}`

[Larpoux]

Oh, yes. Recorder

[Larpoux]

I am going to look to Flutter Sound code.
Btw: bitRateis not used in case of PCM. The correct parameter is sampleRate

How do you know that your parameter bufferSize does not work?

[Stimm4]

Yes, that was a test, I usually use sampleRate.

I used the function below, that print at each frames the size of the buffer.
And this size is equals to 355 or less sometimes. (Different to the desired value)

void processAudio(Int16List buffer) { final Pointer<Int16> ptr = calloc(buffer.length); ptr.asTypedList(buffer.length).setAll(0, buffer); print('Process audio data! + buffer.length = '+(buffer.length).toString()); // _processAudio(ptr, buffer.length); calloc.free(ptr); }

[Larpoux]

Here is the Flutter Sound code :

		int minBufferSize = AudioRecord.getMinBufferSize
			(
				sampleRate,
			      	channelConfig,
				tabCodec[codec.ordinal()]
			) * 2;

			int bufLn = Math.max(minBufferSize, bufferSize);

[Larpoux]

bufferSize variable is supposed to be your parameter.

[Stimm4]

I tried to set the bufferSize to 1200, but I got the same size (355).

If the code below :
int minBufferSize = AudioRecord.getMinBufferSize
(
sampleRate,
channelConfig,
tabCodec[codec.ordinal()]
) * 2;

int bufLn = Math.max(minBufferSize, bufferSize);

If he size of the buffer returned is 355, that means, that I'm able to set it to a value higher than 355 ?

[Larpoux]

Things are not so simple 👀
The variable bufLn that I computed is used :

				// gets the voice output from microphone to byte format
				if ( Build.VERSION.SDK_INT >= 23 )
				{
						n = recorder.read(byteBuffer.array(), 0, bufLn, AudioRecord.READ_NON_BLOCKING);

				}
				else
				{
						n = recorder.read(byteBuffer.array(), 0, bufLn);
				}

bufLn is the size of my buffer. But Android can give me a packet smaller.

[Larpoux]

because we don't want to BLOCK when Android >= 23

[Stimm4]

Ho Drat!
So Impossible to be sure to have the exact bufferSize set with READ_NON_BLOCKING.
Thank you for your response !