The Nyquist-Shannon sampling theorem is the rule that makes digital audio possible: to represent a signal perfectly you must sample it at more than twice its highest frequency. The half-the-sample-rate limit is the Nyquist frequency, so 48 kHz sampling covers everything up to 24 kHz, just beyond human hearing. Anything above that limit must be removed by an anti-aliasing filter before the ADC, because frequencies past Nyquist don't disappear — they fold back into the audible band as false tones (aliasing). The theorem is why 48 kHz is enough for video, and why pushing higher mainly buys filter headroom rather than audible bandwidth.
The book · Volume 4 of 7
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
The Nyquist theorem explains why 48 kHz is enough for video sound and why poor resampling filters still create aliasing. This volume covers Nyquist in depth with sample rates, anti-aliasing, resampling and bit depth, so you can choose capture and delivery rates with clear reasons rather than habit. Written by Nikolay Sapunov, CEO at Fora Soft.
Choosing sample rates and resampling filters with the Nyquist limit in mind?
Tell us your capture and delivery chain and we will recommend sample rates and resampling settings that avoid aliasing and wasted bandwidth. 250+ video products shipped since 2005.
