Flutter record Package: Recorded Audio Contains Silence After 1 Minute

Question

I'm using the record package in Flutter to record audio. The recording process seems to work without any errors, but the resulting file contains only the first minute of audio, followed by complete silence.

Here is my recording code:

Future<void> _startRecording() async {
  try {
    // Get the app-specific external storage directory for music
    final directory = await getExternalStorageDirectory();
    if (directory == null) {
      debugPrint('Directory is null');
      return;
    }

    // Create the directory if it doesn't exist
    final voiceDirectory = Directory('${directory.path}/VoiceNotes');
    if (!voiceDirectory.existsSync()) {
      voiceDirectory.createSync(recursive: true);
    }

    // Generate the file path using the app-specific directory
    String filePath = '${voiceDirectory.path}/VoiceNote_${_generateTimestamp()}.3gp';

    // Start recording using the generated file path
    await _audioRecorder.start(
      const RecordConfig(encoder: AudioEncoder.amrNb),
      path: filePath,
    );

  } catch (e, stackTrace) {
    debugPrint('Error while recording: $e');
    debugPrint('Stack trace: $stackTrace');
  }
}

Steps I Have Taken:

• Checked the debug logs. The recording process appears to be working without issues.
• Ensured the stop() method is called at the end of the recording.
• Verified permissions for microphone and external storage are granted.
• Tested with different devices, but the issue persists.

Observations:

• The debug logs show no errors during recording.
• The resulting file plays correctly for the first minute but is silent afterward.
• I am using the amrNb encoder to save the audio as .3gp files.

Questions:

• What could cause the recorded file to contain silence after a specific duration?
• Are there known issues with the amrNb encoder or .3gp format when using the record package in Flutter?
• How can I debug or resolve this issue to ensure the full recording is saved?

Any suggestions or solutions would be greatly appreciated! Thank you.