DSP for digital audio

Excepting live performances, the audio path from performer to consumer is via a sound recording or broadcasting route. In either case, some form of signal processing equipment is used, even if only a level control and equalisation. Digital audio is used for some or all of this audio path with digital storage and/or processing, bracketed by appropriate A/D and D/A conversion. The need to maintain a white noise floor throughout the audio signal chain causes many differences between digital audio processing and other DSP application areas. The steps taken to achieve this goal are illustrated in the design considerations for recursive filters. Some differences between mainstream DSP and audio DSP are: arithmetic (fractional fixed-point), requantizing (dithered truncation), and filter topologies (Direct Form I or similar with a single quantizer and error feedback)