That’s Our Cue! Updates for the FADGI Embedded Metadata Guidelines and BWF MetaEdit for the Cue Chunk in Broadcast Wave Files

This is guest post, the first in a series of updates about the recent work of the Federal Agencies Digital Guidelines Initiative (FADGI) Audio-Visual working group, is co-authored by Kate Murray, Digital Projects Coordinator in Digital Collections Management and Services, audiovisual archivist and technologist Dave Rice, and Jérôme Martinez, Founder and President of

FADGI Guidelines for Embedding Metadata in Broadcast WAVE Files, version 3

Fig. 1. Guidelines for Embedding Metadata in Broadcast WAVE Files, version 3.

The Federal Agencies Digital Guidelines Initiative (FADGI) Audio-Visual working group and  pleased to announce the publication of Guidelines for Embedding Metadata in Broadcast WAVE Files (PDF) version 3 (see figure 1) and corresponding updates led by Jérôme Martinez from MediaArea for the open source BWF MetaEdit application. 

These revised guidelines, last updated in 2012, reflect a collaborative effort to respond to ongoing community needs and changing expectations. Project partners RiceCapades (Dave Rice and Ashley Blewer) conducted interviews with FADGI members from the Library of Congress’ National Audio-Visual Conservation Center and the Smithsonian’s Center for Folklife and Cultural Heritage as well as the broader user community represented by public radio station WNYC and Northeast Document Conservation Center’s Audio Preservation Services to help identify the evolving needs of the audio preservation practitioners at large.

The Broadcast WAVE format continues to be one of the most used formats for preservation files, thanks in part to its flexible nature and ubiquitous inclusion in both proprietary and open source software. It is also a format recommended by the ARSC (Association of Recording Sound Collections) and IASA (International Association of Sound and Audiovisual Archives) technical committees, as well as being a preferred format for the the Library of Congress Recommended Formats Statement.

Two of the most significant updates to the 2021 FADGI guidelines are:

1) A new section on the use of the Associated Data List chunk to provide labels, comments and other context for embedded “cues” (which mark a specific point of special interest in the audio data such as a change in speaker, start of a speech or vocal arrangement). Based upon the original file format specifications, the Cue Chunk (<cue>), Associated Data List chunk (<adtl>) and sub chunks Label (<labl>), Note (<note>), and Labeled Text (<ltxt>, figure 2) described in this revision provide guidance for enhanced uses of these optional metadata fields.

Example of FADGI Guidelines entry for Labeled Text chunk values

Fig. 2. Example of FADGI Guidelines entry for Labeled Text chunk values.

2) Expanded values in the CodingHistory element for sampling frequency, bit depth and mode beyond what is listed in EBU R98 to reflect current needs and tool capabilities as well as definitions for subelement labels. For example, to clarify the use of the ‘mode’ subelement in CodingHistory, FADGI, states that ‘mode’ is a synonym for ‘sound field’ and includes definitions for allowable mode values (mono, stereo, dual mono, joint stereo, multitrack, multichannel and other).

A complete change list is included in the 2021 FADGI guidelines.

Guidelines are all well and good as a concept, but users need tools and applications to put guidelines into action. The key driver in updating the FADGI guidelines was the ongoing expansion and development of the popular BWF MetaEdit application.  BWF MetaEdit is the leading free open source tool for embedding, validating, and exporting metadata in Broadcast WAVE Format files, including the updated FADGI ruleset profile for the cue and adtl chunks.

bext and INFO list chunk

Fig. 3. bext and INFO list chunk.

New cue and adtl chunk editor pop out

Fig. 4. New cue and adtl chunk editor pop out.

BWF MetaEdit was originally funded by the Library of Congress and FADGI starting in about 2010 to support the first version of the FADGI guidelines including use of the bext chunk. Initially developed by AVP and now maintained by MediaArea, BWF MetaEdit provides a user friendly cross platform interface to:

  • Import, edit, embed, and export specified metadata elements in WAVE audio files including bext and INFO chunks and now cue and adtl.
  • Export technical metadata from Format Chunks and minimal metadata from the bext and INFO chunks as comma-separated values and/or XML, across a set of files or from individual files.
  • Evaluate, verify and embed MD5 checksums, as applied to the WAVE file’s data chunk (audio bitstream only).
Exported cue and adtl chunk data as XML

Fig. 5. Exported cue and adtl chunk data as XML.

BWF MetaEdit not only supports the FADGI guidelines but also specifications from the European Broadcasting Union (EBU), Microsoft, and IBM.

A key change in the development to support the 2021 FADGI guidelines was the use of the GitHub Issue Tracker to encourage transparent engagement and reporting across multiple user communities. Progress and status reports are public for all to read, comment on and update.

While FADGI is continuing support for BWF MetaEdit to meet the ongoing needs of the FADGI guidelines ruleset, anyone can sponsor development for additional features or rulesets.  And with over 40,000 downloads and counting, BWF MetaEdit continues to lead the way for transparency and responsiveness to the changing needs of the audio digitization and preservation communities.