Sample rate

What it means

Digital audio is a series of measurements of the sound wave. The sample rate is how many of those measurements are taken per second, written in kilohertz. At 48 kHz, the standard for video, the signal is measured 48,000 times every second; 44.1 kHz is the music CD standard.

A higher sample rate can represent higher frequencies: the limit is half the sample rate, so 48 kHz covers up to 24 kHz, beyond human hearing. That is why 48 kHz is enough for nearly all video work. Sample rate is separate from bit depth, which defines how precisely each sample is measured, and from bitrate, which describes the compressed data rate of the whole file.

How it works in practice

Action cameras record audio at 48 kHz, typically compressed as AAC inside an MP4 or as uncompressed audio in some modes. Phones and most external recorders also default to 48 kHz for video.

Keep everything at 48 kHz in a video project: camera audio, external recorders and music. Editors convert other rates automatically, but it is cleaner to start matched.

Higher rates such as 96 kHz are useful for sound designers who slow down effects, but they create bigger files with no audible benefit in a typical highlight video. Leave cameras at their default unless you have a specific reason to change it.

What to watch out for

Mixed sample rates in one project are handled by the editor, but a wrongly tagged file can play at the wrong speed and pitch. If a clip sounds slightly too high or low and drifts against video, check its sample rate.

Some recorders default to 44.1 kHz for music use. When combined with 48 kHz video, sync can drift over long takes, see audio sync.

Sample rate does not fix quality problems. A 96 kHz recording of wind noise is still wind noise, so microphone placement matters far more than the number.