Output from AVURLAsset.audiovisualMIMETypes for easy reference.

AVURLAsset.audiovisualMIMETypes()

(lldb) p types
([String]) $R0 = 56 values {
  [0] = "video/mp4"
  [1] = "video/x-m4v"
  [2] = "video/mpg"
  [3] = "audio/x-m4r"
  [4] = "audio/AMR"
  [5] = "video/x-mpg"
  [6] = "video/3gpp2"
  [7] = "video/mp2p"
  [8] = "video/mp1s"
  [9] = "audio/mpeg"
  [10] = "video/x-mp2p"
  [11] = "video/x-mp1s"
  [12] = "audio/scpls"
  [13] = "audio/wave"
  [14] = "video/x-mp2t"
  [15] = "video/x-mpeg2"
  [16] = "audio/mpeg3"
  [17] = "video/mpeg"
  [18] = "audio/aac"
  [19] = "video/x-m2ts"
  [20] = "audio/x-caf"
  [21] = "video/mp2t"
  [22] = "audio/3gpp"
  [23] = "application/x-mpegurl"
  [24] = "application/mp4"
  [25] = "audio/mp3"
  [26] = "video/avi"
  [27] = "application/vnd.apple.mpegurl"
  [28] = "audio/mp4"
  [29] = "audio/x-aiff"
  [30] = "audio/mpg"
  [31] = "video/x-mpeg"
  [32] = "video/dv"
  [33] = "video/3gpp"
  [34] = "video/mpeg2"
  [35] = "audio/x-mpg"
  [36] = "audio/x-mpeg"
  [37] = "audio/3gpp2"
  [38] = "audio/x-aac"
  [39] = "audio/x-wav"
  [40] = "video/quicktime"
  [41] = "audio/x-mp3"
  [42] = "text/scc"
  [43] = "audio/x-mpegurl"
  [44] = "audio/x-mpeg3"
  [45] = "audio/x-m4a"
  [46] = "audio/x-m4p"
  [47] = "audio/mpegurl"
  [48] = "video/m2ts"
  [49] = "audio/aacp"
  [50] = "audio/x-m4b"
  [51] = "audio/aiff"
  [52] = "audio/x-scpls"
  [53] = "audio/basic"
  [54] = "audio/wav"
  [55] = "text/vtt"
}