digital sound for the analogue video recorders then in use [15]. To accommodate the audible range, the standard uses 2 16 = 65 536 quantisation levels. The bit rate of a CD recording is therefore 44 100 samples/s * 16 bits/ sample * 2 (for stereo recording) to be equal to 1.411 Mbps. For 60 min of music the total number of bits required is calculated as follows: = 1.411 Mbps * 3600 S = 5.08 gigabits 12 620 megabytes (MB) kilobyte = 1024 bits). CD Size The audio CDs were initially designed to have a diameter of 11.5 cm, equal to the diagonal length of a compact audio tape. This size provided an audio capacity of approximately 60 min of music. The size was increased to the present 12 cm diameter because an executive at Sony decided that CDs should be able to contain his favourite recording of Beethoven's 9th symphony, which was 74 min long (needing 760 MB) [15]. Free Lossless Audio Codec The correlation between neighbouring digital audio samples can be used to reduce the number of bits necessary to represent an audio signal without loss of information. Free lossless audio codec (FLAC) is one such audio coding technique which can compress digital audio by up to 50-60%. A FLAC decoder can reconstitute the digital audio without loss of information [16]. MP3 Standard A source audio coding system was designed as part of a project on digital video coding, and standardised by the Moving Pictures Expert Group (MPEG). MPEG-1, the first standard release contained three audio codecs, MPEG-1 Audio Layers I, II and III. These are better From Analogue to Digital known as MP1, MP2 and MP3, respectively. All three standards are lossy coding of audio, that is, the encoded audio is not an A to D conversion of the input analogue audio signal. MP1 encodes audio by sampling at 32, 44.1 and 48 kHz and produces output at variable rates from 32 to 448 kbps. It was used in digital compact cassettes, a now discontinued prod- uct. MP2 also encodes analogue audio by sampling at 32, 44.1 and 48 kHz, and produces a compressed digitised audio st