An audio codec is the pair of algorithms — coder and decoder — that compresses audio into fewer bits for storage or transport and reconstructs it on playback. Lossy codecs (AAC, Opus, MP3) throw away detail a psychoacoustic model predicts you won't miss, reaching large savings; lossless codecs (FLAC, ALAC) shrink files while restoring the original bit-for-bit. A codec is not a container: AAC is a codec, MP4 is the file that carries it. Choosing one trades off quality at a target bitrate, latency, CPU cost, licensing, and device support — which is why video uses AAC, real-time uses Opus, and Bluetooth uses LC3.
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
Picking an audio codec sets the bitrate, latency and device support of everything that ships after it. Volume 4 covers audio codecs in detail, from PCM, sampling and bit depth to Opus, AAC and speech codecs, with loudness and real-time voice processing, so you can choose the codec for each delivery path with numbers rather than habit. Written by Nikolay Sapunov, CEO at Fora Soft.
Choosing an audio codec, Opus or AAC, for calls, live streams and VOD in one product?
Tell us your target devices and delivery paths, and we will send an audio codec matrix with bitrates and latency for each one. 250+ video products shipped since 2005.
