1. A computer-implemented method comprising: converting, by a computer processor, a digital signal between a first format and a second format, one of said first and second formats including multiple descriptions of the digital signal, the converting including: storing a first set of pixels of the digital signal into a first input register; taking selectively a first subset of the first set of pixels from said first input register and placing the first subset in an orderly way in a first output register; and taking a second subset of the first set of pixels from said first input register and placing the second subset in an orderly way in a second output register.