I've tried converting the video with ffmpeg
but the x265
library which uses for encoding the file into HEVC does not have support for Alpha Channel.
I found some proprietary tools that convert files to HEVC, which support Alpha Channel, but they don't convert them to HLS compatible formats.
I've also tried with AWS MediaConvert, but the Alpha Channel was lost.
Is there some tool that converts videos into HEVC + Alpha Channel + HLS + fragmented MP4?