I'm trying to play an H265 video in opus audio format using iOS HLS, and a video slice file in fmp4 format, and I found that on iPhone13 ios 17.5.1, it plays fine, but on iPhone X ios 16.5.1, it doesn't play. Is it because some iOS versions do not support HLS in the opus audio format?
So far as I am aware, Opus audio is only supported beginning in iOS 17, and only in MP4 files. According to the Authoring Guidelines you should also supply AAC to maintain compatibility with older versions. Please note that Opus is not listed as a supported codec in either the Guidelines or the Tech Specs.