.mov       muxed       lossless v and a
.m2v       video
.ac3         audio
    lossy
     smaller



.mov       h.264
             instagram

two pass vbr best

  vbr = variable bit rate

   8mb/sec


two pass vbr = best
v.b.r varibal bit rate      better resolution
file size larger   = 3 hours
slow


c.b.r constant bit rate
less resolution
file size smaller   = 1 hour
fast

metadata
muxed/ multiplexed = video/audio