Media Source Extensions Notes

A collection of findings experimenting with Media Source Extensions on Chrome 36.

• Specifying an audio and video codec when creating a source buffer but passing in an initialization segment with only a video track results in a decode error

ISO Base Media File Format (BMFF)

Init Segment

A working initialization segment is outlined below. It may be possible to trim this structure down further.

• ftyp
• moov
  • mvhd
  • trak
  • tkhd
  • mdia
    • mdhd
    • hdlr
    • minf
  • mvex

Media Segment

The structure of a minimal media segment that actually encapsulates movie data is outlined below:

• moof
  • mfhd
  • traf
  • tfhd
  • tfdt
  • trun containing samples
• mdat

Structure

sample: time {number}, data {array} chunk: samples {array} track: samples {array} segment: moov {box}, mdats {array} | moof {box}, mdats {array}, data {array}

track chunk sample

movie fragment -> track fragment -> [samples]