EVOLUTION OF PORTABLE AUDIO DEVICES

PHONAUTOGRAM

Period: Mar 17, 1860 to Mar 15, 2016

Mechanical analog; sound waveform transcribed to paper or glass

Phonograph cylinder (Edison)

Period: Mar 15, 1877 to Mar 15, 2016

Mechanical analog; hill-and-dale grooves, vertical stylus motion

Ediphone - Dictaphone

Period: Mar 15, 1878 to Mar 15, 1916

Mechanical analog, The Ediphone and subsequent wax cylinders used in Edison's other product lines continued to be sold up until 1929 when the Edison Manufacturing Company folded

Electrical cut record

Period: Mar 15, 1925 to Mar 15, 2016

Mechanical analog; electrically cut from amplified microphone signal, lateral grooves, horizontal stylus motion, discs at 7", 10", 12", most at 78 rpm

High Definition Compatible Digital (HDCD)

Period: Mar 15, 1986 to Mar 15, 2016

Digital. Redbook compatible physical CD containing 20–24 bit information (uses linear pulse-code modulation (LPCM)

SILK

Period: Mar 15, 2009 to Mar 15, 2016

Digital. Codec developed by Skype, extended into the Opus codec

DCP

Period: Mar 15, 2010 to Mar 15, 2016

Digital. Auro-3D codec

OPUS

Period: Mar 15, 2012 to Mar 15, 2016

Digital. OPUS-3D codec