Digital recording technology
Microphones
MIDI
Guitar and Amplification
Samplers and Drum machines
Synthesis and synthesizers
Effects and Processors
Digital audioDistribution formatsAnalogue recording
DAT tape
Digital audio tape (DAT), favored in studios in the 1980‘s + 1990’s.Nowadays beening superseded by hard disc recording.
Used mainly for VHS tapes and was a cost effective multi-track solution.
Allowed users to record digitally onto a 4mm magnetic tape.
Developed by Sony and introduced in 1987.
DAT is recorded at 48, 44.1 or 32 kHz sample rate at 16 bits quantization. -It can be cloned exactly the same as it doesn’t use lossy data compression.
MiniDisc 1992: Developed by Sony.
Highly portable.
Made using an Magneto-optical material.
A laser beam was used to heat the magnetic material changing the characteristics.
An electromagnet would read these changes.
Could record for up to 74 minutes.
Used Sony’s audio compression format (ATRAC), so lost some characteristics of the sound.
History of the CD 1979: Philips demonstrated a 11.5 cm Optical Disk and a Compact Disc
Audio Player could produce high quality audio signals.
1982: Philips and Sony collaborated to produce a standard format and player technology.
1985: Philips and Sony developed computer-readable CD-ROM.
1990: Philips and Sony developed the CD-Recordable CD-R.
2000’s: CD’s had replaced the audio cassette player, but since sales have dropped due to the increase in digital audio formats.
1990: CD-Re-Writable (CD-RW) was developed, presenting copy write issues.
1991: Sony developed minidisc, created with no physical contact between lasers and disc, not wearing out after repeated writings.
CD recording
A digital file is made up of ‘0’ or ‘1’, known as binary code.
These ‘0’ and ‘1’ are grouped together into larger numbers where a computer
processor can decode.
This is stored by a laser burning ‘pits’ into the surface for every ‘0’,
leaving a black ‘land’ when there’s a ‘1’.
This can be converted back to audio signal.
Basics of a CD player
Data is read from the centre out. Data is held in bumps
and read using laser pickup.
Spindle motor spins the disc between 200 –
500 rpm.
Tracking motor moves the laser pickup so it can follow the spindle motor.
Last few decades computer capabilities and memory have become increasingly powerful.
Software packages are more available and less specialised.
Currently Windows and Mac are computer market leaders.
Audio Interfaces have become cheaper and more capable.
Recording quality only once produced in professional studio in 70’s and 80’s can be carried out on laptops because of the increased computer power of faster processors and larger RAM.
Through audio compression techniques, digital music transfers over the internet are the normal, iPods and mobile phones can reproduce music of a very acceptable quality.
Brief history of digital advancements
Digital sound“Digital audio refers to technology that records, stores, and reproduces sound by encoding an audio signal in digital form instead of analog form.”
To convert this sound from analog into a digital format:- Measurements of pitch, volume, timbre and other useful info are taken at regular intervals, a mathematical description is built of the sound.
- Each measurement is called a ‘sample’.
The less that is sampled, the poorer the the quality of the audio would be as there would be lots of gaps. - For example Wav has a higher sampling rate than MP3 is technically worse quality more of the audio is missing.
CODECS - "coder-decoder" Not related to dynamic compression
Research into auditory marking and perceptual coding in the 1970’s found that the human ear rejects a good deal of information and therefore not hear all of the material presented in recording. [1]
Formats that are CODECS: MP3, WMA, AAC………….
MP3 Commonly known as an MP3.
1993: MPEG-1 Audio layer III, was published.
1995: MPEG-2 Audio layer III, was developed and published.
An encoding format for digital audio which uses a form of lossy data compression.
Lossy compression algorithm is the compression of binary data into a form which when it is re-expanded has all most all of of the original information.
Audio can only be compressed at the ratio of 10:1 without noticeable loss in quality. [1]
It has revolutionized how music is brought/listened too, with physical copies being out sold by data downloaded played back via digital audio players.
The difference
Lose dynamic and frequency range.
FLAC – Free Lossless Audio Codex 2001: FLAC was first developed by Josh Coalson.
It is a free software.
Typically reduces audio to 50-60% of its original size.
Uses lossy compression, in comparison to others can be streamed and decoded quickly.
AAC – Advanced Audio Coding
Due to better processing is known to have higher quality sound than MP3.
AAC is used in YouTube, iPhone, iPod……
Uses Lossy compression.
WMA – Windows Media Audio 1999: WMA was developed by Microsoft as part of there operating
system.
2003: professional lossy codec was released by Microsoft for professional use.
WAV (Waveform Audio File Format) 1991: WAV released Microsoft and IBM audio file format.
The usual bitstream encoding is the linear pulse-code modulation (LPCM) format.
Uncompressed
Audio is sampled at regular discrete intervals.
Samples are rounded to the nearest discrete number at a fixed spacing, known as quantization.
The amplitude values are at a consistent level to the amplitude.
AIFF – Audio Interchange File Format 1988: AIFF was developed by Apple computer
Uncompressed
It uses uncompressed PCM (Pulse-Code Modulation)
• The amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps.
Digital audio players1997: SaeHan Information Systems, was created becoming the first
mass produced digital audio station.
2001: This saw the sale of the iPod, prominently popular with Mac users.
2003: MP3 player was introduced to mobile phone.
Computer based recording Hard Disc recording gradually replaced tape RAM (random access memory) systems began to replace
hardware multi-track recorders This contributed to the ability to access any point in the audio
and edit it non-destructively, this is called non-linear editing. Digital Audio Workstations (DAW) are when a personal
computer used with appropriate software such as Logic, Pro Tools, Cubase.
Audio interface/soundcards
Offered a cheaper and capable way of recording line in or microphone.
Audio Interfaces take an analogue signal and convert it into a digital signal for it to be read by a computer.
DAC (Digital to Analogue converter) is used to convert the signal back to audio and are contained within an audio interface.
Soundcards are found within a computer, and to record multiple audio channels at once it would need to be a multi-channel soundcard.
Advantages / Disadvantages
• Low noise
• Can be processed or manipulated easily
• Sent online accessed globally
• Easy to index and reference
• Can be though to be cold sounding
• Digital technology can not facilitate same type of sound manipulation as analogue technology.
• Audio has to be saved somewhere else when hard drive is full.
