MPEG-2 is a video coding format, first standardized in 1995 and revised in 2013. Due to relatively low computational complexity this standard gained popularity and massive native implementations in video hardware. Hence MPEG-2 has actually become a standard in satellite and cable broadcasting. MPEG-2 is also used for creating DVDs for the same reasons (native hardware support by DVD players).

SPHERE (SPeech HEader Resources) is a file format defined by NIST (National Institute of Standards and Technology) and is used with speech audio. SoX can read these files when they contain μ-law and PCM data. It will ignore any header information that says the data is compressed using shorten compression and will treat the data as either μ-law or PCM. This will allow SoX and the command line shorten program to be run together using pipes to encompasses the data and then pass the result to SoX for processing.