== Subtitles in MP4

Tests:


  MP4Box -add $video -add $audio -add $st:name=Deutsch:lang=de:hdlr=sbtl:group=2 -new Desktop/jazz-v2.m4v
    IsoMedia import - track ID 1 - Video (size 1920 x 1080)
    IsoMedia import - track ID 1 - Audio (SR 48000 - 2 channels)
    Timed Text (SRT) import - text track 1920 x 1080, font Serif (size 18)
    Setting up iTunes/iPod file...
    Saving Desktop/jazz-v2.m4v: 0.500 secs Interleaving

  * QT7 : HUGE!!
  * QTX : too big
  * iTu : too big
  * VLC : too small

Same but .mp4:

  * QT7 : No subtitles!!
  * QTX : too big
  * iTu : too big
  * VLC : too small

Subler: OK everywhere (but very big)


What are these options? 

  :hdlr=sbtl ?
  :group=2 ?
  :layer=-1 ?
  -3gp ?