Issues in Digital Audio That Persist To This Day

There has been a lot of argument, dispute, complaining, and shouting about tracks being too loud or too close to digital maximum. In this talk, we will show:

• what happens to your signal, its spectrum, and its loudness (remember, loudness is a perceived quantity)
• how this affects the ability to be transmitted via bit-rate reduction systems
• how it affects standard “lossless” codecs
• using graphics and audio clips, what happens to your music when you clip it digitally, cause intersample overs, and/or hypercompress in the name of LOUD
• how this sort of clipping causes aliasing of other clipping byproducts and how intersample overs make a DAC fall apart in a different way
• how a pleasant sound can become something else altogether
• using a variety of statistics on particular clips taken directly from their intended digital delivery streams, exhibiting clipping, what one might call enlightened clipping, level compression, intersample overs, changes in loudness over a track, and how much spectral dynamic range there is in a variety of digital streams
• that encoding/decoding such streams, especially with lossy codecs can create MORE clipping and MORE intersample overs, forcing both more distortion and higher required data rates for the reduced-rate music.

We are not going to talk about artistic judgements that are supposed to be LOUD, but rather about what happens after mastering when a clip has been pushed beyond reason.

KEEP IT DOWN A BIT. If you want to clip, do leave some headroom. That way, rather than having a delivered result that depends entirely on the actual DAC the listener is using, you can guarantee your market a consistent experience.

About AES

The Audio Engineering Society is the only professional society devoted exclusively to audio technology. Founded in the United States in 1948, the AES has grown to become an international organization that unites audio engineers, creative artists, scientists and students worldwide by promoting advances in audio and disseminating new knowledge and research.

Currently, over 12,000 members are affiliated with more than 75 AES professional Sections and more than 95 AES student Sections around the world. Through local Section events, members experience valuable opportunities for education, professional networking and personal growth.

About IEEE

The Institute for Electrical and Electronic Engineers, or IEEE (eye-triple-e), is the world’s largest technical professional society serving professionals in all areas of electrical, electronic, and computing technologies. Due to its size and breadth of technical interests, the society is comprised of “chapter societies” representing the major sub-fields of study in electrical and computer engineering. Signal processing encompasses a wide-range of mathematical and computing techniques for the analysis, synthesis, and transformation of data. Hot topics in the group today include: music information retrieval, speech recognition and synthesis, acoustic event detection, and audio spatialization to name a few.

Speaker(s): JJ Johnston, Bob Smith

Location:
Digipen Institute of Technology
9931 Willows Rd
Redmond, Washington
98052