Media Presentation Description

An MPD can be used to describe media presentations with one or multiple Dolby AC-4 bitstreams.

Although the syntax of the MPD is capable of using common XML elements to describe almost any media format, the encoding type and the configuration of a Dolby AC-4 bitstream that is part of a content presentation constrain the parameter values of some of these elements.

The MPD supports these scenarios:

  • Legacy signaling using the attributes and elements of AdaptationSet for stream selection

    In this scenario, the media presentation references several Dolby AC-4 bitstreams, with each single AC-4 presentation being contained in its own bitstream, except for the case of immersive stereo content where two presentations are included but treated as one in the MPD.

  • MPEG‑DASH next-generation audio signaling using Preselection elements for AC-4 presentation and stream selection
    In this scenario, the media presentation references either one of the following items:
    • one single Dolby AC-4 bitstream containing all available audio components that are utilized by one or more AC-4 presentations (preselections).
    • multiple Dolby AC-4 streams, which contain all or part of the audio components that are utilized by multiple AC-4 presentations (preselections).
  • A combination of the above two scenarios
library_booksNote: Depending on the application specification for which the encoded media is created, content creators might consider deviating from the guidelines described in this document. An example is a situation where multipresentation AC-4 bitstreams are intended be provided to receivers that do not support the ISO base media file format broadcast TV profile.