Researched
Digital Compression (JPEG, MP3, H.264)
JPEG (1992) and MP3 (standard 1993) shrank pictures and music to a fraction of their size by dropping what eye and ear barely notice; H.264 (2003) did the same for video and made streaming practical.
Open in the interactive tree →Lossless coding dates from Huffman in the early 1950s; Nasir Ahmed's discrete cosine transform (1972-74) lets images and sound be stored as frequency parts, many of which can be coarsely rounded or discarded. Karlheinz Brandenburg's team at Fraunhofer built MP3, which cuts CD-quality audio to about one eleventh at 128 kbit/s; H.264 saves 50% or more of the bits compared with MPEG-2 for the same video quality. Sandvine's 2024 report put on-demand video streaming at 54% of downstream traffic on the networks it measures.
Prerequisites
- Fourier Analysis1822Transform coding stores a signal as frequency components, most of which can be rounded.
- Information Theory1948Entropy sets how far data can shrink, and what can be dropped.
Unlocks
- Smartphone2007Phones store and stream photos, music and video only because codecs shrink them many times over.