How can I convert an HEVC video with Alpha Channel to HLS with fragmented MP4?

Question

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?

Answer 1

mediafilesegmenter is an Apple tool which is capable of converting an HEVC video with alpha channel to HLS streaming while preserving the transparency. It can use fragmented MP4 by providing the -r option. It can be downloaded via the Apple Developer site.

Other tools like ffmpeg that use the x265 encoder don't have support at the time to preserve the alpha channel with HEVC.