48-Bit Integer Processing Beats 32-Bit Floating Point for Professional Audio: Applications
James Anderson Moorer · 1999
The emergence of new consumer formats for the delivery of digital audio into the home places ever more pressure on professional systems for maintaining the highest possible audio quality throughout the production process. For a while, it was thought that the 32-bit floating point processors provided a simple and adequate solution to the issues of dynamic range and scaling inherent in professional audio processing. It is clear now that even more precision is required to produce a finished product of 24-bit PCM at sampling rates of 96 KHz to 192 KHz. This paper discusses the differences between fixed point and floating point computation with respect to the audibility of computational error, and makes a case for the use of 48-bit integer processing as the standard by which professional systems should be measured. Floating-point has always been admired for its freedom from scaling and dynamic-range problems. It makes it possible to design digital filters without worrying about scaling problems in the state variables. Mixdown busses can be arbitrarily wide in terms of number of channels without fear of overflow. Since the 32-bit IEEE-752 floating point format allows 24 bits of mantissa (including the sign bit), it has been