Serial ADM

Serial ADM is a new professional audio metadata format derived from the ADM file format as recomended by Recommendation ITU-R BS.2076. Like PMD, Serial ADM enables a new set of use-cases aimed at supporting next generation audio features such as:

  • Immersive audio
  • Dialogue enhancement
  • Multi-Language and audio-description support
  • Commentary/Dialogue selection and adjustment
  • Audio-object movement
  • Headphone virtualization

Serial ADM is specified in Recommendation ITU-R BS.2125. This does not specify the method of carriage but describes how the XML document is placed into a serial frame-based structure. The only carriage method to be standardized so far is using AES3 with SMPTE ST 337 formatting which will be documented in the soon to be published standard SMPTE  ST 2116.

A sequence of Serial ADM frames is called a flow. The ADM metadata carried by a flow can be seperated into two groups:

  • Time variant dynamic metadata
  • Time invariant static metadata

An Serial ADM flow can use one of the following flow types:

  • Full-Frame - supports random access on every frame
  • Intermediate-Frame - does not support random access
  • Mixed-Frame - supports random access but not on every frame 
  • Divided-Frame - supports random access on some frames with data-rate smoothing

Serial ADM Flow Types

A Serial ADM metadata authoring application can select the appropriate flow type for the application. Situations where immediate random access is important may use Full-Frame mode whereas other applications where data-rate considerations are more important may use Divided-Frame mode.

Sample Streams

This zipfile contains 4 Serial ADM test streams in three different formats: XML, PCAP and WAV

Each Serial ADM stream covers a different use-case or scenario:

  • 51_main.sadm - 5.1 Main with 1 presentation
  • 51_eng_and_spa.sadm- 5.1 M&E plus English and Spanish dialogue tracks with 2 presentations
  • 514_eng_spa_vds.sadm - 5.1.4 M&E plus English and Spanish dialogue and VDS tracks with 4 presentations
  • 514_4objects.sadm - 5.1.4 M&E plus 4 dialogue objects in different positions with 4 presentations

Audio Metadata Authoring Tool

The Audio Metadata Authoring Tool is a Windows based application that allows the user to easily author metadata in both PMD, ADM and Serial ADM formats. The application supports the following features:

  • Multiple audio objects and presentations
  • Selection of audio object type (Dialog, VDS etc.)
  • Selection of audio object position gain and divergence
  • Language and presentation name language selection
  • HTTP post to specified URL
  • XML file output with update trigger to enable downstream streaming