Problems of Forensic Sciences 2018 Vol. 115 (CXV) 241-261
METADATA IN AUDIO FILES COMPLIANT WITH ISO/IEC 14496-12 AND THEIR CHARACTERISTICS AS WELL AS THE EVALUATION OF USABILITY IN THE INVESTIGATION OF THE AUTHENTICITY OF RECORDINGS
Marcin MICHAŁEK
Institute of Forensic Research, Kraków, Poland
Streszczenie
In recent years evidence recordings examined during authentication analysis are recorded in a digital form. Currently a majority of these recordings is being made with mobile devices, mainly mobile phones. These devices usually capture recordings in compressed formats such as 3GP and MP4 in the version with audio only, i.e. M4A. In these types of files data is saved in accordance with the ISO/IEC 14496-12 standard ISO Base Media File Format. Therefore, a significant amount of additional information is stored in the form of so-called metadata besides encoded multimedia in the 3GP and MP4(M4A) file formats. Analysis of the metadata in the file is currently one of the basic methods in process of the authenticity analysis of digital recordings. The structure of files compliant with the mentioned standard consists of objects called boxes containing metadata with information on the recording format and parameters as well as the date and time of the registration. During the work audio recordings in the 3GP and MP4(M4A) formats were recorded using mobile devices, and then the structure of these files was analysed with regard to the ISO/IEC 14496-12 standard. The results of the research show that the metadata of the 3GP and MP4(M4A) file formats contain relevant and useful information for the authenticity analysis of recordings stored in such type of files.
Słowa kluczowe
Authenticity analysis; Digital recording; File structure; ISO/IEC 14496-12.