Fast ASS watermark replacement and removal added, with support for multiple time ranges

ASS watermark replacement now supports multiple time ranges. After configuring ASS watermarks for several periods, you can change them without transcoding the whole video again: only the watermarked sections are processed. For example, if the source video is 2 hours long and the ass watermark appears for a total of 5 minutes, replacing it processes only 5 minutes of video rather than the entire 2-hour video. This greatly improves processing efficiency, and the resulting M3U8 link stays unchanged. Other watermark types will be supported later, including static or GIF image watermarks, scrolling text, moving image watermarks, and text watermarks at random positions.

Added watermarks can also be removed quickly and efficiently, taking roughly a few seconds per video. You can therefore replace them with new watermarks or remove the added watermarks almost whenever you need.