Last Updated: 20050909, tendeloo
Saturday, October 8, 4:30 pm — 6:30 pm
T12 - Audio Compression
John Strawn, S Systems Inc. - Larkspur, CA, USA
Audio compression involves removing certain parts of the signal, with the goal of reducing the data rate without impacting the audio quality much if at all. In this tutorial, which will include sound examples, we start with an overview of the perceptual bag of tricks in perceptually-based codecs such as MP3 and AC-3. Perceptual insights are often combined with mathematical innovations, such as the discrete cosine transform. For R&D engineers, there will be information about methods for implementing the DCT. We will show how the building blocks can be assembled into the basic structure of a perceptual encoder and decoder. As time allows, we will review the basic families of codecs, including where MP3 fits in and look at nonperceptually-based codecs. Finally, building on the theory covered here, there are tips for the recording engineer making an MP3 to minimize undesired artifacts.