[HELP]: Inconsistent Record Buffer Size

[MuhammedSaygili]

Hello,

Even though I change the buffer size of the audio captured from the microphone, I still receive audio packets in random sizes depending on the sample rate, rather than a fixed buffer size.

Here is the output of this code: samplerate=16000

Future<void> startRecordingAndSendUDP() async {
    if (_mRecorderIsInited && !isRecording) {
      isRecording = true;
      _sendCommand(utf8.encode("SEND"));

      var recordingDataController = StreamController<Uint8List>();
      _mRecordingDataSubscription =
          recordingDataController.stream.listen((soundBuffer) {
        print(soundBuffer.length);
        _sendCommand(soundBuffer);
      });

      await _mRecorder!.startRecorder(
        toStream: recordingDataController.sink,
        codec: Codec.pcm16,
        numChannels: 1,
        sampleRate: sampleRate,
        bufferSize: 1024,
      );
    }
  }

Additionally, even if I set the bufferSize value to 4096, I still receive these variable sizes.

Result:

flutter: 2732
flutter: 2730
flutter: 5546
flutter: 2732
flutter: 2730
flutter: 2730
flutter: 2732
flutter: 2730
flutter: 5546
flutter: 2732
flutter: 2730
flutter: 2730
flutter: 2732
flutter: 2730
flutter: 5546

Additionally, when I increase the sample rate to 44100Hz, the buffer size varies between 8192 and 9600.

If I'm not mistaken, I was previously using an older version of the flutter_sound package due to a version conflict with some other packages, and I don’t recall having this issue then. However, since I can't downgrade the version now, I'm not completely sure about this.

flutter_sound version used: 9.16.3 Test environment: iOS 17

[MuhammedSaygili]

@Larpoux Do you have any information about this?

[Larpoux]

The buffer size that you specify in flutter sound is relative to the internal buffers used, and is not tied with the size of packets. On iOS, flutter sound uses 4 buffers with the specified size. The only thing important is that flutter sound has enough buffer so that audio data are not lost.

[MuhammedSaygili]

Got it, thank you for the information. By the way, I think flutter_sound does not support pcm8. Is there any other method you can suggest other than reducing 16 bit pcm to 8bit?