A Sample Rate Converter (SRC) is a processor or algorithm that converts digital audio signals sampled at one sample rate to a completely different sample rate.
Sample rate converters can convert sample rates up and down. For example, a down conversion is when the sample rate of a 96 kHzDVD is converted to the sample rate of a 44.1 kHz compact disc( CD). To prevent the converted file from containing interference, antialiasing filters filter out corresponding frequencies.
In the case of an up-conversion, the upper frequency ranges contain no information because, after all, there was no information in the source file with the low sampling rate.