Digital Audio Media

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In this section we will be examining support systems that allow audio signals to be stored in digital form. Clearly in this case factors such as the sampling frequency and quantization bits that may degrade the system need to be taken into consideration before the signal is stored. Once the digital signal has been stored, degradation, yet being present still, is less likely to take place. The great advantage of storing the signal in digital format lies in the fact that this way all possible manipulations in the digital domain can take place, and therefore in some cases no loss of information occurs[38 ]. To copy a signal from one support to another (for example onto a computer) single bits are transferred and thus the sequence is reproduced unblemished without introducing errors on the destination support. On the other hand, if we were to copy an analogue track onto another analogue support degradation would occurr (just think what happens if you copy a signal from one tape to another over and over again: eventually the hissing would be so high that it would cover the original signal, which, moreover, in the meantime will have lost much of its frequency content. Whereas this whole process carried out digitally would take place without any loss of information whatsoever!). In digital support systems the audio signal firstly gets converted into digital through the sampling process [Sampling ] and thereafter it is stored in the form of digital data; in order to listen to the original signal another conversion from digital to analogue is required. Once the signal has been converted and stored as data, it will be far less exposed to degradation: numerical information is stored in a different manner compared to analogue signals[39 ]. Now let's take a look at the most commonly used digital media in sound engineering. We will divide them into three categories: magnetic, optical, and magneto-optical.




[38 ] Every time a conversion from analogue to digital takes place, part of the information transported by the signal itself is irredeemably lost.

[39 ] Digital supports allow information to be stored in bit form. As well as the support itself being more trustworthy, bear in mind that we can add a whole set of other data to the audio signal information, for the correction of potential reading errors. One of these is the parity check which will be explained in just a moment.







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