[edit] Introduction
Description: “ the word digital refers to a quantitive numeric form and analog refers to the continue physical quantity. To digitalize something means to converts an analog physical quantity into a numeric value”. A system of sound recording in which sound is represented as a series of discrete electrical measurements, expressed in binary numbers. The sound wave, converted into an electrical analogue by a microphone, is sampled and measured over time (for a musical CD, 44 100 samples per second). Each voltage measurement is then assigned a binary number. ...
- www.collectionscanada.ca/gramophone/m2-153-e.html
[edit] Digital Recording
AIM: the goal is to create a recording with very high fidelity (very high similarity between the original signal & the reproduced signal) and perfect reproduction(the recording sounds the same every single time you play it no matter how many times you play it). To accomplish these two goals, digital recording converts the analog wave into a stream of numbers and records the numbers instead of the wave using an analog-to-digital converter. To play the music, the stream of numbers is converted back to an analog wave by the digital-analog converter. It is then amplified and fed through the speakers to produce sound.
[edit] Digital Recording of the Past
In the Beginning: Etching Tin:
- Thomas Edison is credited with the first device for recording and playing back sounds in 1877 using a phonograph, which scratched sounds onto a tinfoil cylinder using a needle.
- This system was improved by Emil Berliner in 1887 to produce the gramophone which is also a purely mechanical device using a needle and diaphragm. The gramophone’s major improvement was the use of flat records with a spiral groove.
Thomas Stockham and Soundstream:
- An American Scientist who developed the first audio recording system, and pioneered techniques for digital audio recording and processing as well.
- Known as “the father of digital audio”.
- He founded Soundstream Inc. in 1975.
- The company developed a 16-bit digital audio recording system using a 16 track Honeywell instrumentation tape recorder as a transport, connected to digital audio recording and playback hardware of Stockham’s design.
- Soundstream provided commercial services for recording computer based editing. It was the first commercial digital recording company in the U.S.
- Stockham’s developments and contributions to digital audio, paved the way for later digital audio technologies such as the audio compact disc and DAT(digital audio tape).
- Soundstream’s digital editing system was the first instance of a computer used to edit commercial recordings. It attempted to develop a home digital player that would use a photographically reproducible ‘optical card’ as opposed to the mechanically pressed CD.
What actually happens:
As already mentioned in order to record a sound in digital format the sound must be converted from analog to digital or, for the purposes of this assaignment ‘A/D’.
[edit] Steps:
- The analog sound is created
- The filter then eliminates sound above a certain frequency in order to avoid distortion.
- The a/d converter then converts the analog signal into a digital code.
- The dsp (digital signal processing) is performed on the signal, digital dither is also added (Dither is a form of noise, or 'erroneous' signal or data which is deliberately added to sample data for the purpose of minimizing quantization error. Dither is routinely used in processing of both digital audio and digital video data) http://en.wikipedia.org/wiki/Dither/.this process is necessary for minimizing digital error. The information from the output can be stored in various different formats, e.g. magnetic tape, optical disk, or RAM (random access memory). Before storage the series of coded is given extra lines of code to allow for error correction. This detects and corrects the errors during playback
- Before the d\a conversion the digital dither must be added to numbers with regards to amplitude of the digital signal, only if digital signal processing as been performed.
- The d\a converter simply converts the digitl signal into ann analog signal.
- The output low pass “LP” filter’s task is to eliminate certain frequncys that are too high. This process is done during D\A conversion. (http://www.digital-recordings.com/publ/pubrec.html)
[edit] Applications:
With the advantage of storage size and the advantage that digital signals offer high quality signal over long distance which will never deteriorate.
Processing of a digital signalis also more practical than that of an analog. Apart from the fact that the quality does not deteriorate during dsp, dsp also, the dsp can perform tasks that would be physically impossible during asp. Digital recording has also made it possible for high quality recording equipment be available to a people who wish to avail of it. Funtions available during dsp include, reverberating pitch change, voice recognition, pitch change and much more.
The ability to change the input without damaging or performing destructive editing has allowed people to experiment with sound in ways unavailable to and analog signal.
[edit] Future Digital Recording
- Mark DeLoura: turned his home computer into a digital video recorder using one of several new products that are emerging as alternatives to the VCR. DeLoura can record TV shows on his PC and burn the programs he wants to keep onto DVD.
- The growing variety of new digital recording products and the declining sales of blank videotapes, suggests that the VCR’s quarter-century reign in home entertainment may be beginning to wind down. “I think that you can see that by 2008 or 2010 that digital recording will be as much in the dominant position as the VCR is now”- Jay Strivatsa.
- DVD set top devices record TV programs in digital form on an internal hard drive instead of the analog videotape.
- The DVD player introduced in 97’ has become the hottest-selling home consumer electronics device in history.
[edit] More Products:
- Bungee DVD; a USB connected device made by Pinnacle Systems Inc. It is a combination TV tuner, video capture and graphics card.
- On2 Technologies Inc: open source software system called VP Vision, which also turns a PC into a digital video recorder.
- For people who prefer something simple: MedioStream of San Jose introduced Software that bypasses a computer’s hard drive and burns any video in realtime directly to a recordable DVD or CD.
[edit] Big Companies Step in:
- Sony: recordable DVD drives and GigaPocket- a program that records TV programs on the hard drive.
- Apple: macintosh computers equipped with its recordable DVD SuperDrive and digital video editing tools.
- Pioneer, Philips, Panasonic & Samsung: are pushing digital recording from the TV side.
- Philips: sells DVD recorders that use the Philips backed DVD&R and DVD&RW format.
- Panasonic: DVDR985 offers DMR-E20, which can record on DVD-RAM or DVD-R discs with up to 12 hours of storage space and can also replay the first part of the show while recording the last part.
- Digital Recording gives viewers the chance to record their favourite shows automatically and skip past commercials.
[edit] The Future Product
KORG 1 bit recorder
- Super portable Mobile Recorder (MR) break new ground by providing high fidelity 1 bit recording.
- Hand held
- Enables conversion of your 1 bit recordings and mixes into all of today’s audio formats without degradation- you’re ready for the future!
- Ideal for source recording, podcasting, broadcast journalism, as well as archiving final mixes and master recordings.
- Pristine fidelity, offers lifelike imaging and analog quality depth.
- What comes in…comes out! With no manipulation needed. You can even convert to newer formats that will be adopted in the future, be they multi-bit or a future migration of the 1 bit format of the future.
- AudioGate software for Mac&PC can convert 1 bit recordings into WAF&AIFF formats at various bit rates and vice versa.
- KORG MR-1000: perfect tool for the professional who wants to record and archive their final images in the studio. While it’s compact size and portability make it ideal for location recording. After editing and recording all your tracks in the DAW/hardware system of your choice, you can mix directly or via the analog summing mixer to the MR-1000.
- High speed USB connectivity allows easy file transfer to and from a computer.
[edit] Advantages of digital recording :
(taken from http://www.digital-recordings.com/publ/pubrec.html)
Advantages Digital Analog
Larger memory: 93db 65db
Less distortion 0.005% 0.02%
Frequensy response 0 – 20,0000 30 – 20,0000
Loss of s/n* Nothing perfect copy 3db
Deterioration over time No Yes
- Loss of s/n (signal to noise ratio): Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering concept defined as the ratio of a given transmitted signal to the background noise of the transmission medium. It is also known as D/U ratio, which stands for desired to undesired signal ratio.
[edit] Bibliography: