Digital Signal Processing
Laboratory digitalLAB

Forensic audio services, audio enhancement and restoration!

Audio file formats vs. sound quality.


The most popular audio file formats:

  • wav (wave form audio format):
  • wma (Windows Media Audio):
    • audio files with compression by Microsoft,
    • smaller file size than wav,
    • audio quality is dependent on applied compression level,
       
  • m4a (MPEG-4 Audio Layer):
    • audio files with compression by Apple,
    • smaller file size than wav,
    • audio quality is dependent on applied compression level,
       
  • mp3 (MPEG-1/MPEG-2 Audio Layer 3):
    • audio files recorded with compression,
    • file size similar to .wma,
    • audio quality is dependent on compression level,
       
  • amr (3gp, 3ga), (Adaptive Multi-Rate):
    • strongly compressed audio coding scheme,
    • the smallest file size,
    • high compression rate = very low audio quality!!!
    • You shouldn't use this file format if audio quality is important!!!
       

The best audio quality is provided with wav file format.


Audio files like wma and mp3 having low compression rate allow us to keep relatively good audio quality. However when compression rate grows audio quality drops respectively!


amr (3gp, 3ga)  type files provide us with lowest audio quality and must be avoided if we want to obtain good audio quality!!!


Voice recording setup:


Set, always, the highest recording quality on recording device to avoid audio compression! If you set up "longest recording time" your recorder will use high level of compression to save recording memory space. As a result you will have a lot of audio data but with very poor quality which might be useless.


Preferred audio file recording settings: