一键水印-专业水印视频编辑大师 is a free utility and tools app available for iPhone. Developed by Chongqing tuanshui technology Co. Ltd., this app offers various video editing features and functions. Users can trim the duration of videos, change video covers, and select covers from their photo albums. The app also allows users to modify the video canvas, adjusting the background and exporting high-definition videos based on specific aspect ratios. Additionally, users can add their desired audio to videos, compress video sizes without compromising the quality, and apply text or image watermarks. The app even provides a video reverse feature to create interesting effects. Please note that the app offers a subscription service for continuous access to VIP features. For more information about the subscription and privacy policy, please refer to the provided links.