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A Short Overview of Digital Audio |
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What is Digital Audio
Digital audio is made up of audio signals that are stored in a digital format. Digital audio includes all of the following processes or activities:
- Audio conversion:
- Analogue to digital conversion (ADC)
This is the conversion of an analogue audio signal into a digital audio signal. This process involves sampling and quantization.
- Digital to analogue conversion (DAC)
This is the conversion of digital audio into an analogue signal for playback and distribution.
- Audio signal processing
This involves processing of any digital signal in some way and applying various functions like echo, reverb etc. to it.
- Storage, retrieval, and transmission of digital audio in various storage formats such as CDs, MP3, Ogg Vorbis, etc.
The digital audio process begins with the sound being converted into electrical signals which are simply ‘on/off’ pulses. This is in contrast to older analogue recording where the signals are electro-mechanical signals. The most important feature of digital audio is that it is possible to copy and transmit it with ease. Digital audio is also said to be more efficient than analogue because it results in lower data loss. This argument is justified by the fact that in any studio environment, sound signals would pass through cables, mixing desks and processing equipment a larger number of times before the recording is finally mixed down in a single track. This would lead to a larger amount of loss if the recording is analogue.
The basic aim of conversion of analogue signals to digital audio is to keep the resultant digital data as close as possible to the original recording. However, many digital audio formats results in a ‘lossy’ conversion, that is, the digital data produced would lack in quality as compared to the analogue one. In spite of this, this loss is actually undetectable by the human ear. The lossy formats simply discard the information which is usually undetectable by human ears while listening to a digital recording. This is true of the most widely used format over the world, the MP3 file format.
When converting to digital audio, data may also be lost due to misreading while conversion. However, error correction and interpolation techniques have been used to correct this to a certain extent. The only step where the information is lost is when the analogue signal is being converted into digital signals or vice versa.
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