Digital recording technology

1. Digital recording technology Microphones Synthesis and synthesizers Guitar and Amplification Effects and Processors MIDI Samplers and Drum machines Analogue recording Distribution formats Digital audio

2. DAT tape • Developed by Sony and introduced in 1987. Digital audio tape (DAT), favored in studios in the 1980‘s + 1990’s. Nowadays beening superseded by hard disc recording. • Allowed users to record digitally onto a 4mm magnetic tape. • 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. • Used mainly for VHS tapes and was a cost effective multi-track solution.

3. MiniDisc • 1992: Developed by Sony. • A laser beam was used to heat the magnetic material changing the characteristics. • Made using an Magneto-optical material. • An electromagnet would read these changes. • Highly portable. • Could record for up to 74 minutes. • Used Sony’s audio compression format (ATRAC), so lost some characteristics of the sound.

4. History of the CD • 1982: Philips and Sony collaborated to produce a standard format and player technology. • 1979: Philips demonstrated a 11.5 cm Optical Disk and a Compact Disc Audio Player could produce high quality audio signals. • 1985: Philips and Sony developed computer-readable CD-ROM. • 1990: Philips and Sony developed the CD-Recordable CD-R. • 1991: Sony developed minidisc, created with no physical contact between lasers and disc, not wearing out after repeated writings. • 1990: CD-Re-Writable (CD-RW) was developed, presenting copy write issues. • 2000’s: CD’s had replaced the audio cassette player, but since sales have dropped due to the increase in digital audio formats.

5. 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.

6. Basics of a CD player Data is read from the centre out. • Spindle motor spins the disc between 200 – 500 rpm. • Data is held in bumps and read using laser pickup. • Tracking motor moves the laser pickup so it can follow the spindle motor.

7. Brief history of digital advancements • 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.

8. 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.

9. CODECS - "coder-decoder" • Not related to dynamic compression • Research into auditory marking and perceptual codingin 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………….

10. Commonly known as an MP3. 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] • Lose dynamic and frequency range. The difference • It has revolutionized how music is brought/listened too, with physical copies being out sold by data downloaded played back via digital audio players.

11. FLAC – Free Lossless Audio Codex • It is a free software. • 2001: FLAC was first developed by Josh Coalson. • Typicallyreduces 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 • Uses Lossy compression. • Due to better processing is known to have higher quality sound than MP3. • AAC isused in YouTube, iPhone, iPod……

12. 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.

13. Uncompressed 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. • 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.

14. Uncompressed AIFF – Audio Interchange File Format • 1988: AIFF was developed by Apple computer • 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.

15. Digital audio players 1997: 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.

16. 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.

17. 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.

18. 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.