Convert nist to amr

What is the difference between .nist and .amr?

Description: 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.; An AMR file is an audio file saved in a compressed audio format developed by Ericsson. It is used by many 3G cell phones for voice recordings such as MMS messages. AMR files incorporate the Algebraic Code Excited Linear Prediction (ACELP) algorithm, which is designed to efficiently compress human speech audio.