title: Access Unit and AUD in Transport Stream
body: <p>What data should an access unit contain? </p>
  
  <pre>
  
      [SPS][PPS][IDR][PFrame][BFrame]
  
  </pre>
  
  <p>is an access unit?
  I got the concept that, access unit delimiters are required in ts packet. But, if the source file(I am using .264 file as input) do not contain AUD? then should I add AUD explicitly? If yes, then of how many bytes?
  Should it be the following?</p>
  
  <pre>
  
      0x00000169(of Header+1 Byte)
  
  </pre>
  
  <p>And where should I add the AUD?
  Currently my TS file contains this formation: </p>
  
  <pre>
  
      [TS Header][PES Header][SPS][PPS][IDR][PFrame][BFrame][TS Header]...
  
  </pre>
  
  <p>Is this structure okay? Also, can one access unit contain multiple I frames?</p>