Provided your source is MP4 and you are converting to fragmented MP$, I came to a conclusion on the below post. Stereo video HLS - https://developer.apple.com/forums/thread/743503?answerId=775862022#775862022 I arrived at a solution. I came to realized that fMP4 (fragmented MP4) in the error was in reference to the output format rather than the source format. mediafilesegmenter defaults to ts segmentation rather than fMP4. I added -iso-fragmented option to the command so it looked similar to the demo script below. mediafilesegmenter -iso-fragmented -t 4 -b https://www.example.com/spatial_video_stream/ -f ~/path/to/dir/with/file spatial_video.mov

I arrived at a solution. I came to realized that fMP4 (fragmented MP4) in the error was in reference to the output format rather than the source format. mediafilesegmenter defaults to ts segmentation rather than fMP4. I added -iso-fragmented option to the command so it looked similar to the demo script below. mediafilesegmenter -iso-fragmented -t 4 -b https://www.example.com/spatial_video_stream/ -f ~/path/to/dir/with/file spatial_video.mov Reference post that helped: https://developer.apple.com/forums/thread/71433

Update on my end: I decided to using mediafilesegmenter Version 1.20.9 (618.21b-230614) to keep all software tooling Apple, however I ran into the following error: Jan 1 2024 16:44:06.294: Fragmented MP4 is the only supported container format for the segmentation of HEVC content Jan 1 2024 16:44:06.294: Unsupported media type 'hvc1' in track 0 Jan 1 2024 16:44:06.294: Unable to find any valid tracks to segment. Segmenting failed (-12780). Again, I'm trying to segment MV-HEVC (mp4) files which I converted using use the mvhevc1440x1440 AVOutputSettingsPreset with some overrides. My codec key is still hvc1 from the preset which makes sense for this error. What is confusing is that the hls recommendations (1.10) recommend hvc1. So I'm not sure why I'm getting an unsupported media type error.

Hey did you get around this? Additionally, what file types were you looking to segment? I'm running into this error as well with Version 1.20.9 (618.21b-230614), while trying to segment MV-HEVC which uses the mvhevc1440x1440 AVOutputSettingsPreset with some overrides. However, I my codec key is still hvc1 from the preset. What is confusing is that the hls recommendations 1.10 recommend hvc1.