can not resolve method getActivity()が出ます。androidで、Serviceで、Camera2APIで動画を撮影したいです

can not resolve method getActivity()が出ます。どうすればいいのでしょうか？
Serviceでこのコードを使用したいです。

java
1 private void setUpMediaRecorder() throws IOException {
2
3        mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
4        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
5        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
6        if (mNextVideoAbsolutePath == null || mNextVideoAbsolutePath.isEmpty()) {
7            //この下のgetActivity())のところに、can not resolve method getActivity()
8            mNextVideoAbsolutePath = getVideoFilePath(getActivity());
9            //この上のFilePathも直さないと
10        }
11        mMediaRecorder.setOutputFile(mNextVideoAbsolutePath);
12        mMediaRecorder.setVideoEncodingBitRate(10000000);
13        mMediaRecorder.setVideoFrameRate(30);
14        mMediaRecorder.setVideoSize(mVideoSize.getWidth(), mVideoSize.getHeight());
15        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
16        mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
17        WindowManager windowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
18
19        int rotation = windowManager.getDefaultDisplay().getRotation();
20        switch (mSensorOrientation) {
21            case SENSOR_ORIENTATION_DEFAULT_DEGREES:
22                mMediaRecorder.setOrientationHint(DEFAULT_ORIENTATIONS.get(rotation));
23                break;
24            case SENSOR_ORIENTATION_INVERSE_DEGREES:
25                mMediaRecorder.setOrientationHint(INVERSE_ORIENTATIONS.get(rotation));
26                break;
27        }
28        mMediaRecorder.prepare();
29    }