Generate hls stream using h265 codec

I tested this with ffmpeg 4.1.1 today on macOS 10.14.3, and it seems to work beautifully. I do have to transcode to an MP4 initially (can't just go direct to HLS manifest during the transcode stage as the resulting m3u8 is unplayable in Safari – seems like a ffmpeg bug), but the packaging function appears to work perfectly well, and I am able to play the resulting HEVC HLS m3u8 (in UHDp60 HDR10 even – albeit with quite a bit of buffering on my iPhone XS Max and a non-tone-mapped display in macOS) in Safari on both macOS 10.14.3 and iOS 12.1.2.

As stated above, I first need to transcode to MP4 (the following example takes a UHDp60 HEVC HDR10 input and transcodes to 1080p60 HEVC HDR10):

ffmpeg -y -i source.mp4 -c:v libx265              \
    -tag:v hvc1 -pix_fmt yuv420p10le -s 1920x1080 \
    -x265-params "colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc:bitrate=4000:keyint=120:strict-cbr" \
    -c:a copy ~/Sites/HLS/1080p/HDR10.mp4

From the resulting file, I can then do the HLS packaging:

ffmpeg -y -i ~/Sites/HLS/1080p/HDR10.mp4 -c copy \
    -hls_segment_type fmp4 -hls_time 6 -hls_list_size 10 \
    -hls_flags delete_segments+append_list+split_by_time \
    -hls_playlist_type vod ~/Sites/HLS/1080p/HDR10.m3u8

The output from these steps produces all the necessary files to be able to logon to my web server and automatically play the HLS playlist in Safari. Safari can even play streamed HEVC HDR10 MP4 files from a web server now. So I would suggest attempting to do that first – if your original MP4 doesn't play in Safari via the web server, then it is unlikely that an HLS packaging of it will either.

I've also been having problems with getting ffmpeg to generate a valid HLS playlist with HEVC/h265 files with version 4.3.2 that will play in Safari. VLC plays them just fine though. Upgrading to ffmpeg v4.4 also seems to completely break HLS generation for h264 files as well.

I ended up just letting ffmpeg transcode to hevc for me, and then used bento4 to fragment it (using bento's mp4fragment) and then generate the HLS playlist for me (using bento's mp4dash with the --hls option enabled)