MediaRecorder在Samsung S7上记录零长度

Question

我一直在尝试使用MediaRecorder录制音频剪辑。我已经阅读了许多教程和文章，但是我的代码在我的Samsung S7手机上不起作用。该应用具有清单中的所有权限，可以写入外部存储并访问麦克风。该文件已创建，但长度为零，无论代码运行多长时间，大小通常仅为32个字节。

有人可以帮助我吗？这是我的代码：

var query = (from...
        where...
        select q).TakeRandom(1);

这是没有错误消息的日志：

private void createRecorder() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) == PackageManager.PERMISSION_GRANTED) {
        recorder = new MediaRecorder();
        recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
    }
}

public void onRecorderClicked(View v) {
    if (((ToggleButton) v).isChecked()) {
        createRecorder();
        if (recorder != null) {
            final String dir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getPath() + File.separator + getString(R.string.app_name);
            final File folder = new File(dir);
            if (!folder.exists()) {
                folder.mkdirs();
            }
            final String fileName = dateFormat.format(new Date()) + ".3gp";
            final String path = dir + File.separator + fileName;
            recorder.setOutputFile(path);
            try {
                recorder.prepare();
            } catch (IOException e) {
                e.printStackTrace();
            }
            recorder.start();
            MediaScannerConnection.scanFile(this,
                    new String[]{path}, new String[]{"audio/3gp"},
                    new MediaScannerConnection.OnScanCompletedListener() {
                        @Override
                        public void onScanCompleted(String path, Uri uri) {
                            Log.i("ExternalStorage", "Scanned " + path + ":");
                            Log.i("ExternalStorage", "-> uri=" + uri);
                        }
                    });
            Toast.makeText(getApplicationContext(), "Recorder started: " + fileName, Toast.LENGTH_SHORT).show();
        }
    } else {
        if (recorder != null) {
            recorder.stop();
            recorder.reset();
            recorder.release();
            recorder = null;
            Toast.makeText(getApplicationContext(), "Recorder stopped", Toast.LENGTH_SHORT).show();
        }
    }
}