Thursday, February 25, 2010

The iZotope 64-bit SRC™ utilizes a hy...

The iZotope 64-bit SRC™ utilizes a hyrbrid algorithm providing the highest quality and most customizable resampling available on the market today.
Sample Rate Conversion (SRC) is a necessary process when converting material from one sampling rate (such as studio quality 192kHz) to another rate (such as CD quality 44.1kHz). It is common to record and edit in high sampling rates since higher rates allow higher frequencies to be represented. For example, a 192kHz audio sample can represent frequencies up to 96kHz whereas a 44.1kHz audio sample can only represent frequencies up to 22.05kHz, also known as the Nyquist frequency. 

When reducing the sampling rate, or downsampling, it is crucial to remove the frequencies that cannot be represented at the lower sampling rate. Leaving frequencies above this point causes aliasing. Aliasing can be heard as the frequencies in an inaudible range are shifted into an audible range causing distortion and noise. 

With Zotope 64-bit SRC's steep low-pass filter, users can completely avoid the common aliasing artifacts while maintaining the maximum frequency content.
iZotope 64-bit SRC features a hybrid ringing control enabling a compromise between the standard pre-ringing of a linear phase filter and the post-ringing of a minimum phase filter. A continuous control morphs the algorithm from a linear phase filter to a minimum phase filter (shown below in an intermediate step). 

The intermediate design also maintains a linear phase response in the audible range.
Sound card drivers

Professional audio production, broadcast (editors, mastering, trackers, file format converters)

Audio encoders, codecs, decoders 

A/D and D/A converters 

Scientific applications for single-dimensional signals

The key step of sample rate conversion is the quality of the low-pass filter design. The crucial aspects include a flat pass-band, steep transition-band, high suppression in the stop-band, and minimal ringing. The careful attention of iZotope's SRC protects against the loss of data, aliasing, noise, and unwanted ringing artifacts that plague other implementations.