Constraints on Dolby AC-4 elementary streams within HTTP Live Streaming compliant test streams

A Dolby AC-4 elementary stream must meet certain conditions to be delivered via HTTP Live Streaming.

If your product encodes Dolby AC-4 elementary streams, ensure that the product uses the proper settings to meet these requirements. We recommend that an HTTP Live Streaming multiplexer or segmenter reject a bitstream that is not in compliance to prevent problems with subsequent decoding.

A compliant Dolby AC-4 elementary stream must adhere to these requirements:

  • The value of the frame_rate_index parameter must remain constant.
  • The value of the presentation_config parameter must remain constant.
  • The value of the fs_index parameter must remain constant.
  • The value of the channel_mode parameter must remain constant.
  • The value of the content_classifier parameter must remain constant.
  • Constraints described in the Annex E of ETSI TS 103 190-2 must be applied to the Dolby AC-4 bitstream for storage within the ISO base media file format.
  • The Dolby AC-4 random access points must be encoded correctly to ensure compliance with the requirements described in Packetizing the Dolby AC-4 bitstream.

  • We strongly recommend that Dolby AC-4 elementary streams be encoded with the same frame rate as the associated video frame rate to ensure constant alignment of video and audio access units in order to utilize the features of A/V alignment.