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.

Authors: Koenig, Bruce E.; Lacey, Douglas S.
Affiliations: BEK TEK LLC, Palm Harbor, FL, USA; BEK TEC LLC, Stafford, VA, USA(See document for exact affiliation information.)
AES Conference: 2019 AES International Conference on Audio Forensics (June 2019)
Paper Number: 14
Publication Date: June 8, 2019

Click to purchase paper as a non-member or you can login as an AES member to see more options.

No AES members have commented on this paper yet.

Subscribe to this discussion

To be notified of new comments on this paper you can subscribe to this RSS feed. Forum users should login to see additional options.

Start a discussion!

If you would like to start a discussion about this paper and are an AES member then you can login here:
Username:
Password:

If you are not yet an AES member and have something important to say about this paper then we urge you to join the AES today and make your voice heard. You can join online today by clicking here.