Audio Application Notes

Digital Show & Tell, Monty Montgomery, Xiph.org

Monty Montgomery takes us into the lab and uses a series of simple demonstrations to bust some very common myths about digital audio. Test your knowledge of digital audio. This video is fun to watch and easy to understand! Monty takes some difficult concepts and demonstrates them in a clear and simple manner.

Have doubts about Nyquist? Have a fear of stairsteps? Are you worried about ringing? Ever wonder what digital audio does to the timing of transients? This video is for you!

Myth - "Digital audio has stairsteps." 

Myth - "Increased bit depths reduce the stairsteps." 

Myth - "Analog tape has more resolution than digital audio." 

Myth - "Dither masks quantization noise." 

Myth - "Signals lower than one LSB cannot be reproduced." 

Myth - "Digital filters make square waves and impulses ring." 

Myth - "Digital systems cannot resolve timing between samples."

Bit Depth

We now have 16-bit CDs and 24-bit high-resolution recordings available to us. What are the advantages of a 24-bit word length? Are 24-bit recordings better? How many bits do we really need?

Bit depth (also known as word length) indicates how many bits are used to represent each sample in a digital sampling system. Each sample is a snapshot of a signal or voltage at an instant in time. The CD uses 16 bits to represent the voltage of an audio waveform at each instant in time. Other digital audio systems use different bit depths ranging from 1 to 64 bits. It is important to understand the relationship between bit depth and audio quality. The bit depth sets ...

- John Siau

"Low-Resolution Hardware Cannot Deliver High-Resolution Audio"

The music industry is struggling to define High-Resolution Audio or "HRA". In doing so, most have focused on the delivery formats - analog vs. digital, 24-bits vs. 16-bits, 1X vs. 2X and 4X sample rates, PCM vs. DSD, uncompressed vs. compressed.

But, High-Resolution Audio is much more than the delivery format ...

"High-Resolution Audio Requires High-Resolution Performance at all Stages of the Recording and Playback Chain"

- John Siau

This myth goes something like this:

"Analog audio has infinite amplitude resolution."

"Digital audio is limited to a finite number of steps."

"24-bit audio has more resolution than 16-bit audio."

While it is true that digital systems quantize the amplitude of the audio signal to the nearest step in the digital encoding system, this does not necessarily mean that digital systems cannot have infinite resolution. Contrary to popular belief, digital systems can provide infinite amplitude resolution if they are properly dithered.

- John Siau