Digital Audio
Digital audio represents sound as number sequences.
Sound Basics
Frequency (pitch, Hz), amplitude (loudness, dB), timbre. Human hearing: 20 Hz–20 kHz.
Digitisation
Sampling and quantisation. Nyquist: sample rate ≥ 2× highest frequency. CD: 44.1 kHz, 16-bit, stereo.
Audio Formats
WAV/AIFF (uncompressed), MP3 (lossy), AAC (better than MP3), FLAC/ALAC (lossless), OGG Vorbis (open-source).
Processing
Editing, mixing, equalisation, normalisation, noise reduction, effects. Audacity, Adobe Audition.
MIDI
Musical performance data protocol. Tiny files, editable, synthesiser-dependent.
Streaming
Real-time delivery. HLS, DASH. Adaptive bitrate. Spotify, Apple Music.
Summary
Digital audio covers digitisation, formats, processing, and delivery for multimedia.