AES E-Library

AES E-Library

Forensic Authenticity Analyses of the Metadata in Re-Encoded M4A iPhone iOS 12.1.2 Voice Memos Files

Detailed digital data analyses were conducted of the metadata contained in a lossy and a lossless file produced on the iPhone Voice Memos app in iOS 12.1.2. The lossy file was re-encoded with four (4) common audio/media editing programs, producing a total of five (5) separate M4A files. The lossless file was exported to a new lossless file using one (1) of the editing programs, and converted to a new lossless file with iTunes, using an intermediate PCM WAV file. The purpose of this research was to identify changes made to the basic M4A file structure and metadata content by the re-encoding processes as they relate to forensic audio authenticity examinations. The research found that the re-encoding processes produced clearly discernible differences, compared to the original M4A files. The M4A metadata format structure, the procedures followed, the changes identified in the metadata of the re-encoded files, and a discussion of the authenticity implications are listed.

AES Conference:
Paper Number:
Publication Date:

Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!

This paper costs $33 for non-members and is free for AES members and E-Library subscribers.

Learn more about the AES E-Library

E-Library Location:

Start a discussion about this paper!

AES - Audio Engineering Society