intro to daw power point

Intro To DAW

SAE Instructor

Lamarr Miller

Intro To DAW v What is the denition of DAW? v Digital Audio Workstation v A Hardware or computer-based hard disk

recording system that oers multi-track recording, editing and signal processing in one package.

v Extremely dierent from the old school tape reel recording process.

Intro To DAW v What is the denition of DAW? v Audio signals are now almost exclusively

stored and transmitted digitally. v What are the advantages of digital audio?

v No tape noise v Easier to Edit v Does not lose quality when copied

Intro To DAW v Digital Audio Theory v Digital audio is a numerical (Binary) version of

analog audio. v Binary is simply a language. v The English language uses 26 characters v (A-Z) to create words

Intro To DAW v Digital Audio Theory v Binary uses 2 characters v (0 & 1) to create words.

v Each character in a binary word is called a bit and is expressed by wither a 1 or a 0.

v For every bit that you add to a binary word, the total number of values which that word can express doubles.

Intro To DAW v Digital Audio Theory v 1 bit word has values: v 0 = 0 v 1 = 1

Intro To DAW v Digital Audio Theory v 2 bit word has 4 values: v 00 = 0 v 01 = 1 v 10 = 2 v 11 = 3

Intro To DAW v Digital Audio Theory v 3 bit word has 8 values: v 000 = 0 v 001 = 1 v 010 = 2 v 011 = 3 v 100 = 4 v 101 = 5 v 110 = 6 v 111 = 7

Intro To DAW v Digital Audio Theory v So, an audio waveform has to be converted

to binary (0s & 1s) v An audio wave form has 2 basic

characteristics: v Amplitude = (Volume) v Frequency = (Time)

Intro To DAW v Digital Audio Theory v Digital audio represents these characteristics

with: v Bit Depth = (Volume) v Sample Rate = (Time)

Intro To DAW v Digital Audio Theory

v Bit depth is how many 0s and 1s (bits) are used to create 1 binary word. v Each binary word is one

measurement of amplitude (a sample).

v The more bits used for each measurement will result in a higher dynamic range (better delity).


v Sample rate is the number of measurements taken every second. v Each measurement is one sample v It is time based and determines the

frequency response of the recording.

Intro To DAW v Digital Audio Theory v Analog signal moves continually without

break. v Digital recording measures the amplitude

periodically and converts that measurement to a binary number. v It then repeats the process thousands of

times every second v Digital is not continuous v The audio between samples is lost


v An Analog To Digital Converter (ADC) convert the analog voltage uctuations into pulsing binary words by means of a Sample and Hold Circuit.

v A Sample and Hold Circuit measures an instantaneous voltage (amplitude) and holds it steady until an ADC converts it to a binary number.

Intro To DAW v How Sampling Aects Amplitude: v Quantization is the process of assigning a

binary word (numeric value) to represent the value of an amplitude measurement. v Captured as a bit depth. v Represents the amplitude part of the

sampling process. v 4 bits (nibble) has 16 possible values. v 8 bits (byte) has 256 possible values. v 16 bit (word) has 65,536 possible values.

Intro To DAW v How Sampling Aects Amplitude: v Quantization Error is the dierence between each

instantaneous value of amplitude and the quantization value assigned to it by the ADC. v When the analog amplitude falls between digital

values, the ADC must round o the value to the nearest bit.

v More audible in low amplitude signals because only a few bits are used.

v Each additional bit reduces the audible level of quantization error by 6dB.

Intro To DAW v How Sampling Aects Amplitude: v Dither is a solution to quantization error v It is noise added before quantization. v It makes the quantization error less

audible, but is a compromise v A low level hiss for less digital

distortion.

Intro To DAW v How Sampling Aects Amplitude:

v Dither is applied by the ADC, but must also be applied when converting digital audio to a lower bit depth. v Ex: 24 bit audio le to a 16 bit audio

le. v Clipping occurs when the amplitude/voltage

is too high for the ADC to measure v Creates clicks and pops in the audio.

Intro To DAW v How Sampling Aects Frequency: v Sample Rate determines the frequency

response. v Discovered by Harry Nyquist v The Nyquist Theory states that the

highest frequency that can be recreated digitally is the sample rate.

Intro To DAW v How Sampling Aects Frequency:

v In order to record a frequency, the amplitude must be sampled twice per cycle. v Once during compression, and once during

rare fraction. v The Nyquist Frequency is the highest frequency

in a digital system. v Its the sample rate.

v Whats the highest frequency that a 44.1kHz 16 bit system can faithfully reproduce? v 22.05 KHz

Intro To DAW v How Sampling Aects Frequency: v When a frequency is higher than the Nyquist

Frequency, the ADC does not measure it often enough and creates a misinterpreted wave waveform known as an alias le. v The resulting alias is a lower frequency

than the original waveform.

Intro To DAW v How Sampling Aects Frequency: v To prevent aliasing, we send analog audio

thru a LPF before the sample and hold circuit. v These LPFs use very steep roll o rates,

and are known as Anti-Aliasing Filters. v This eliminates frequencies above the

Nyquist Frequency, and therefore eliminates aliases.

Intro To DAW v How Sampling Aects Frequency: v Wordclock is the timing mechanism for the

sample rate. v Sample time is the elapsed time between

measurements v Its the reciprocal of the sample rate (1/

sample rate) v 44100 or 44.1 sample rate is (1/44100) = .

02268ms

Intro To DAW v How Sampling Aects Frequency: v If the wordclock is bad timing drifts between

samples, and jitter occurs. v Jitter is the amount of variation in latency/

response time, in milliseconds. v In addition to frequency response, your

sample rate also aects stereo imaging. v The faster that the samples are recorded,

then your ears receive more ITD information (binaural localization).

Intro To DAW v A typical Analog To Digital Converter (ADC) chain:

Line In Dither Anti Alias Sample & Hold ADC Processing Storage

v Storage and Playback of Digital Audio: v Bandwidth bit rate needed to communicate

all of the digital data. v Bit depth x sample rate x # of channels v Bandwidth of a CD = v 16 x 44100 x 2 = 1,411,200 bits/sec,

approximately 10mb min.

Intro To DAW v Storage and Playback of Digital Audio: v We use that bandwidth because it has been

accepted as the minimal amount of data to create a believable digital recreation of our hearing spectrum.

v 16 bit = 96 db ; 44.1 kHz = 22.05 kHz Nyquist Frequency ; Stereo imaging of 2 channels.

Intro To DAW v Storage and Playback of Digital Audio: v A digital signal that is stereo interleaved

means that it has been multiplexed into one stream of numbers containing both L & R channels.

v The bandwidth of a digital system will aect the audio quality, track count and processing capabilities of a DAW.

v Higher bandwidth requires more processing power.

Intro To DAW v Storage and Playback of Digital Audio: v File compression is sometimes used to

reduce the size of audio les v Lossy Compression: MP3, AAC, WMA, etc. v Reduces delity and le size by reducing

resolution and /or sample rate.

Intro To DAW v Storage and Playback of Digital Audio: v Lossless Compression: Zip, Flac, etc. v Reduces le size, but not delity by

nding redundant data and removing it during compression.

v Replaces the data when expanding.

Intro To DAW v Storage and Playback of Digital Audio: v Connecting Digital Gear: v CDs, DVDs and most digital audio

connections uses Pulse Code Modulation (PCM) to communicate the binary code.

Intro To DAW v Storage and Playback of Digital Audio:

v In PCM, the magnitude of a signal is measured at regular intervals to communicate bits v High level pulse = 1 v Low level pulse = 0

v Wordclock must be synchronized to all machines connected (Master-Slave)


v Digital Connection Types: v AES/EBU: Audio Engineering Society / European Broadcast

Union. v XLR Connector: Transmits 2 channels in one direction.


v Digital Connection Types: v S/PDIF: Sony / Phillips Digital Interface

v RCA Connector: Transmits 2 channels in one direction.


v Digital Connection Types: v ADAT Lightpipe: Alesis Digital Audio Tape

v Optical Connector: Transmits 8 channels in one direction.


v Digital Connection Types: v TDIF: Tascam Digital Interface

v db 24 connector: Transmits 8 channels in both directions.

Intro To DAW v The Development of the Digital Audio

Workstations: v Computer based DAWs have pretty much

replaced alternative recording methods. v Analog tape, digital tape and traditional

hard disk recorders . (i.e. Radar) v As audio recorders moved towards digital,

synthesizers and sound modules did too thanks to MIDI.


Workstations: v All of these digital advancements are

becoming integrated into DAW applications. v Samplers were the beginning of DAWs v Sampler record sound to short digital les

and trigger them using MIDI.

Intro To DAW v The Development of the Digital Audio Workstations:

v The rst instrument to use pre-recorded sounds was the mellotron.

v The rst digital sampler to be mass produced was the EMU Emulator 1 in 1981 which was an 8 bit sampler.

v Samplers became more aordable in the mis 80s. v Akai S612: 12 bit, 32kHz 1 sec storage v $900

Intro To DAW v The Development of the Digital Audio Workstations:

Mellotron

EMU Emulator Akai S612


Workstations: v MIDI (Musical Instrument Digital Interface): v Developed at 1982 NAAM (National

Association of Music Merchants) and introduced in 1983.


Workstations: v MIDI was created so that synthesizers and

samplers could communicate. v MIDI is not audio; Its a communication

language. v Since MIDI is already in the digital domain,

most DAWs have integrated MIDI sequencing.

Intro To DAW v The Development of the Digital Audio Workstations: v First computer based DAW was Post Pro by New

England Digital. v Digidesign quickly became the main computer DAW

with Pro-Tools introduced in 1983. v Pro-Tools created the standard for computer

DAWs. v Sequencing multiple audio tracks to waveform

displays. v Made editing easy and visual.


Workstations: v A DAW is fundamentally like a tape recorder,

but is not linear and now is expected to include sequencing (audio and MIDI), editing, mixing capabilities, and more.

v The power of your DAW can be augmented with 3rd party plugins.

v More RAM, faster processor, or more I/O


Workstations: v The rst DAW you will work with is GarageBand. v A multi-track DAW for audio and MIDI

recording, editing, sequencing and mixing. v What was the rst well-known song to sample

another well-known song?


Workstations: v 1982 song, "Planet Rock", by Afrika Bambaataa

& Soul Sonic Force using a chunk of Kraftwerk's "Trans Europe Express" as a back beat.

v A good DAW operator can manipulate audio in remarkable ways with todays software.

v They are also fully aware of when they are editing destructively, or non destructively.

Intro To DAW v Kraftwerk's "Trans Europe Express.

Intro To DAW v 1982 song, "Planet Rock", by Afrika Bambaataa

& Soul Sonic

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