在android中如何在播放时将RTSP流保存到文件？

import android.media.MediaRecorder;
import android.net.Uri;
import android.os.Environment;
import android.util.Log;

import java.io.File;
import java.io.IOException;

public class RTSPRecorder {
    private static final String TAG = "RTSPRecorder";
    private MediaRecorder mediaRecorder;

    public void startRecording(String rtspUrl) {
        mediaRecorder = new MediaRecorder();
        mediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);
        mediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
        mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
        mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);

        // 设置输出文件路径
        String outputPath = getOutputFilePath();
        mediaRecorder.setOutputFile(outputPath);

        try {
            mediaRecorder.prepare();
            mediaRecorder.start();
            Log.d(TAG, "Recording started");
        } catch (IOException e) {
            Log.e(TAG, "startRecording: " + e.getMessage());
        }
    }

    public void stopRecording() {
        if (mediaRecorder != null) {
            mediaRecorder.stop();
            mediaRecorder.release();
            mediaRecorder = null;
            Log.d(TAG, "Recording stopped");
        }
    }

    private String getOutputFilePath() {
        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_MOVIES), "RTSPRecordings");
        if (!mediaStorageDir.exists()) {
            if (!mediaStorageDir.mkdirs()) {
                Log.e(TAG, "Failed to create directory");
                return null;
            }
        }
        String timeStamp = String.valueOf(System.currentTimeMillis());
        return mediaStorageDir.getPath() + File.separator + "Recording_" + timeStamp + ".mp4";
    }
}

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />