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m4a assets do not display dc format property in AEM

Last update: Mon Apr 27 2026 00:00:00 GMT+0000 (Coordinated Universal Time)

In Adobe Experience Manager (AEM), uploading m4a audio files does not populate the dc:format property, which prevents these assets from being recognized as audio in Asset Share Commons. To fix this issue, configure a custom MIME type mapping for m4a files in the AEM OSGi configuration.

Description description

Environment

Adobe Experience Manager (AEM) On-Premise

Issue/Symptoms

.m4a files do not show the dc:format property after upload and processing, while other formats such as .mp4 and .wav display this property correctly. Because of this, .m4a files are not recognized as audio assets in Asset Share Commons.

Resolution resolution

To fix this issue, follow these steps:

  1. Access the Felix Web Console on the AEM Author instance.
  2. Navigate to OSGi *>*Configuration
  3. Search for Apache Sling MIME Type Service.
  4. Add a new mapping for the .m4a extension with the value audio/mp4 m4a.
  5. Save the configuration.
  6. Verify the added mapping by checking under /system/console/mimetypes.
  7. Reprocess or reupload an .m4a asset.
  8. Confirm that the dc:format property populates and the assets appear as audio files in Asset Share Commons.

Note: This solution applies specifically to environments where AEM does not recognize .m4a files as audio because MIME type mappings are missing out of the box.

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