WWDC Streaming Video

Regular HTTP Live Streaming supplies one m3u8 playlist to the client. Depending on its decoding capabilities and available bandwidth the client will choose one and play it back. If bandwidth drops below a certain threshold, it will choose a lower quality level and try to catch up if possible. This is what regular people do.

However, the 2013 WWDC app has six m3u8 variant playlists per video, packaged within a QuickTime 7 Reference Movie.

  • iPhone Cellular
  • iPhone Wifi
  • iPad Cellular
  • iPad Wifi
  • Apple TV
  • “Snow Leopard”, aka 10.6+

Each variant playlist contains a different mix out of eight quality playlists, optimized for bandwidth and quality considerations per device and connection type.

  • 200 kbit
  • 400 kbit
  • 600 kbit
  • 1500 kbit
  • 2500 kbit
  • 4000 kbit (declares no audio?)
  • 6500 kbit
  • 8500 kbit

…for what essentially are little more than very low motion Keynote slides for most sessions. Why so complicated?