Software and Hardware: Digital
Digital vs. Analogue
Sound can be recorded in either an analogue or a digital format. Digital recording only became a possibility in the 1980’s, so up until then, everything was recorded in an analogue format.
The edexcel definition of analogue is “when a signal or equipment uses a continuously variable physical quantity.” What this really means is that an analog audio signal is an exact copy of an original audio signal, whereas a digital signal represents this original signal in terms of digits or numbers.
Pros and Cons of Digital
✔️ Digital doesn’t require lots of hardware, most of it can be software, so it can take up less space in your studio.
✔️ In a DAW, you can have as many channels as you want and do as many takes as you like. You have a limited tape length and channels in analogue recording.
✔️ Cheaper than analogue because, at the most basic level, you can record with just a computer and a microphone. No need for a whole tape machine.
✔️ The quality never degrades in a digital recording ie. artefacts are not a problem.
✖️ Technology isn’t always reliable. DAWs crash and large projects inevitably slow down the speed of your computer.
✖️ Doesn’t always sound natural. Can sound 'inhuman'.
For pros and cons of analogue, see this page.
Digital Software vs Hardware
Digital audio information can be processed using software and hardware.
Analogue to Digital Conversion
Converting a signal from analogue to digital occurs at the point in your signal chain when the analogue signal from your microphone needs to be read by your computer digitally. A/D converters are (usually) featured within your audio interface.
As explained above, a digital signal represents an analogue signal in terms of digits and/or numbers. An A/D converter works with sample rate and bit depth.
Sample rate takes little “snapshots” of the analogue signal, and controls frequency resolution. It's sort of similar to how you film something – your camera shoots in frames per second and combines all of these frames to make a moving image.
The standard sample rate is 44,100Hz, meaning that 44,100 samples are taken each second. This is commonly expressed as 44.1kHz. The reason for this sample rate being the standard is because of Nyquist’s Theorem.
Nyquist’s theorem states that to fully recreate an analogue signal digitally, the sample rate must be at least twice the highest frequency in the signal. Human hearing ranges from 20Hz to 20,000 Hz, and 20,000 doubled is 40,000. In 44.1kHz sample rate, the extra 4.1Hz is just for safety. The reason why it must be double the highest frequency is to ensure that all the peaks and troughs in the waveform are accounted for.
Bit depth is the resolution of amplitude, as opposed to frequency. The more bits of information you have, the larger the dynamic range. The standard bit depth is for CDs is 16bit and for most streaming services, it is 24bit.
Digital Audio Workstations (DAWs)
A Brief History of DAWs
The DAW, “a piece of software for recording, editing and mixing audio and MIDI files", started life as a MIDI sequencer. It wasn’t until the late 1990s that DAWs could record audio files as well as MIDI.
As with most modern technology, DAWs have more or less obeyed Moore’s law which states that processing power doubles every 2 years. In the beginning, DAWs were massively hampered by the lack of data storage on early hard disk technology. The first version of Pro Tools was released with the ability to record and playback up to 4-tracks only. However, as time went on and as hard disks capacity and speed increased, multitracking became more widely available and cheaper.
DAWs began to reduce the amount of hardware equipment that was needed to record. First they began to replace the old reel-to-reel analogue and digital tape recorders, followed by rack-mounted hardware, dynamic processors and outboard effects units. Mixing desks eventually weren’t necessarily needed either, with audio interfaces and software emulation of various effects being introduced. External rack-mounted hardware and mixers are still used today however in some studios as some producers prefer the sound quality that is created as a result of using these technologies (see this page for pros and cons of analogue)
The invention of the DAW has made producing music far more accessible, and it has resulted in new forms of music such as bedroom pop. It has allowed producers to be more creative in how they work and what sounds can be created.
The Function of the DAW:
To record audio: This is usually done in real-time, meaning that there is a very small delay between the sound wave being captured and it being recorded.
To process MIDI data: This can either come from a physical instrument like a keyboard or from virtual software instruments from within your DAW.
To edit audio: DAWs use non-destructive editing, meaning that any changes that you make can be reversed easily (not permanent). DAWs also allow for non-linear editing, which means that you don’t have to edit in chronological order; you can flit between channels, takes and sections of a project as you please.
To add reverb: The fact that DAWs can add reverb to a signal means that you don’t have to record a signal with a natural reverb which can cause recording problems. Convolution reverb is especially good because you can place your signal in a specific space, such as the Royal Albert Hall or the Sydney Opera House.
To support amp modelling: Amp modelling allows you to record electric guitar and bass via direct injection (DI) without the need for an amp. DI signal is much cleaner than recording an amp, but it can sound a little unnatural, which is where amp modelling comes in. Usually in plugin form in your DAW, amp modelling emulates the sound of different amps, from valve to solid-state.
To support software instruments: Software instruments generate sound when triggered by 'drawn in'/programmed MIDI data or when a key on a MIDI controller keyboard is pressed. Software instruments create sound either via samples of real instruments or using synthesis and sequencers.
Graphical User Interfaces (GUIs)
Graphical user interfaces are the visual, interactive element of computer software. A GUI displays objects that convey information. A DAW is made up of…
a computer, which provides power, storage space for files and processes information..,
a sound card / audio interface, which converts analogue signals into digital signals, and…
…a GUI, which makes the DAW useable and provides the visual/graphical aspects (ie. buttons, sliders, channels etc.)
Digital Consumer Formats
Digital consumer formats are either uncompressed or compressed.
Uncompressed audio files are the best quality because they are perfect representations of the audio recorded, but it results in a large file size.
Compressed files are of lesser quality because in order to compress the file some data has to be discarded, but on the other hand the file size is considerably smaller. Compressed files can either be lossy or lossless. Lossy compressed files lose some audio quality in the compressing process but lossless compressed files don't lose any quality.
Bit rate is how many thousands of bytes (kilobits) of information are stored per second of audio. Bit rate refers to the playback resolution of an audio file, not to be confused with sample rate and bit depth which refers to the resolution at which audio is captured.
The more kilobits there are per second (kbps), the higher the sound quality. Sound files with lower bitrate will have been compressed more than a file with a higher bitrate. At 16bit quality, both CDs and wav files have a bit rate of 1,411 kbps. MP3 files, also at 16bit depth, have a bit rate of 320 kbps. The MP3 file has a lower bitrate because it has been compressed.
Which bit rate you choose depends on the application (streaming services want lower bit rates so transmission rates are quicker) and not all consumer formats have a set bitrate so there are always a few you can choose from.
CD (compact disk)
The CD, or compact disk, was released in the early 80s and were the most popular format from the early 90s to the early 2010s. However, they became less popular when streaming services and online downloads started to become bigger markets.
To get a CD to play, an analogue signal is converted into binary data and written onto the disk. CDs will only play audio files that are at 44.1kHz/16bit. The bitrate of CD audio is 1,411 kbps.
MP3 and m4a/AAC
Both MP3 and m4a/AAC files are compressed, lossy files. Bitrates range from 96 kbps and 320 kbps. Compressed digital formats became popular in the late 1990s because, unlike uncompressed digital formats, they were small enough to be transferred over the internet and be stored on a playback device such as an iPod.
M4a or AAC was designed to become mp3’s successor, but never became quite as widely used due to the fact that its use is limited to Apple products. The advantage it has over MP3, however, is that it can be compressed to smaller sizes while losing the same, if not less, quality.
High Definition Masters
High resolution file formats are created from recordings that have been mastered in better than CD quality (16bit/44.1kHz).
High resolution audio began to emerge in the late 1980s but didn't become available on the consumer market until 1996.
These can be compressed or uncompressed. The advantage of high definition audio files is that they contain more information and have a higher resolution than non-high definition audio files, and therefore sound really great, but due to this they end up being large files. This is why some are compressed.
Uncompressed file types include WAV files and AIFF files. AIFF is Apple's version of WAV.
Compressed files include FLAC and ALAC. Again, ALAC is Apple's version of FLAC. Both are lossless files and can be up to half the size of a WAV or AIFF.
Emerging Technologies
Only in the last few years or so has streaming been the most popular way to access music. The changing model of music distribution means that producers are now mastering with streaming in mind by, for example, applying normalisation and limiting.
Compressed digital formats are used in two ways; for downloading and for streaming. The downloading process is a one time thing whereby you pay for the music and then it is kept, much like an online store. Streaming, however, allows you to listen to whatever you want with a subscription fee, without having to buy the music or own it.
Digital Recording and Sampling Hardware
In the early 1980s, digital technology was introduced to recording. Tape recorders were still used but the tape would store the information digitally rather than in an analogue format. The tape would pass the record head as it did in analogue tape machines, but the information that was recorded to the tape was in the form of a data stream of binary information. It was the invention of digital recording that lead to the introduction and eventual success of the compact disk (CD).
Another way of recording digitally without the use of any software is using a multitrack digital recorder. These devices have preamps and converters built in with storage and memory capabilities (usually via a removable SD card). While multitrack digital recorders are nowhere near as popular as using DAW recording due to track limitations, they are very portable and compact. They are widely used on film sets for capturing on-set dialogue and room tone.
Hardware samplers are devices that use either keyboards or pads to trigger sampled sounds that are stored within the device. Sounds can be loaded on to the device either by the manufacturer or the user. The pitch of a sample can be manipulated to be mapped to a keyboard and the sound that a key or pad triggers can be customised.
Digital Multitrack Recorder
