The foundations of digital audio framed for engineers who built their intuition on video. Eight lessons cover sample rate, bit depth, channels and surround formats, lossless containers (PCM, WAV, FLAC), loudness measurement (LUFS, true peak), audio in MP4 and fMP4, and how audio frames and packets work alongside video tracks. By the end of this block you can read an audio spec sheet, reason about quality vs file size, and avoid the four most common mistakes that produce clipped, out-of-sync, or just-plain-broken audio.