Recently I have been interested in digital signal processing , in particular, multirate DSP . One example is signal compression by subband coding.
Compression means reducing the number of bits in the digital representation of a signal.
Other examples of compression algorithms are JPEG for still images and MPEG for video and audio, both of which are lossy. These algorithms pervade our lives. Multiplying these four numbers gives a requirement of about 20 Mbps. A CD-ROM of 650 Mbytes has therefore 5.2 Gb of memory. So without compression, only 4.3 minutes of video could be stored.