1. If you want to add music to the recorded video, you need to use a third-party APP, taking Xiaoying as an example.
2. First, you need to download and open the Xiaoying app in the mobile app store.
3. Click the clip in the home page option of Xiaoying app and select the small video you want to edit.
4. After selecting the video, click Next to select the soundtrack of the video.
5. If the video originally has sound, click the speaker in the upper right corner to mute the video, and then add the soundtrack.
6. After entering the soundtrack selection page, click on the local music library and select the song you want to match the video.
7. Then click on the progress title at both ends of the song to make the song as long as the video, and then confirm the addition.
8. Finally, click Publish in the upper right corner, and then click Save to Gallery to complete the soundtrack.