digital audio
TRANSCRIPT
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Digital Audio & Technology Application
SamplingQuantization
Digital RecordingReproduction Process
Disk Based Audio System
By Azmawati Binti Mohd Lazim | [email protected]
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Learning Objective
• LO1 - To execute audio recording sessions in a proper studio environment.
• LO2 - To operate the features found in a digital audio workstation and essentially use it as a tool for multimedia production.
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What is sampling?
The term 'sampling'
used in music
production
which is taking
'samples' (or parts)
of an existing music-piece and
using that to create
a new music
production.
converting analogue sound to digital
soundfiles
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The act of capturing an
amplitude value is what is called
‘Sampling’.
A sample is actually a
static representati
on of a waveform in
time.
The amount of samples
that are taken per second is
what’s called the
samplerate.
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Real life situation
If we sample a 20 KHz frequency
with a samplerate of
20KHz, we only have one
sample per cycle.
To capture the +ve and -ve side of the cycle we
will need to have a sampling rate that is double the frequency
that we’re sampling.
In other words : To
capture a 20 KHz
frequency, we’ll need to
have a samplerate of
at least 40KHz.
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Nyquist Theory
• FS = 2 x FN
• FS=Sampling frequency
• FN=Nyquist frequency
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What is quantisation?
Sampling is capturing an amplitude value in time. This value is captured in a process called quantisation
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• As well as with the time axis, digital systems have a certain resolution on the amplitude axis
• The higher this resolution is, the more accurate the digital representation of the waveform’s amplitudes.
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Reproduction ProcessThe higher the bit-depth, the more dynamic range can be captured. So a 24 bits system has a higher resolution than a 16 bits system.
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You can imagine that mixing with audio that has a 24 bit resolution is much easier and pleasant to mix with since we literally have more values on the
amplitude axis.
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Digital Recording
44.1 KHsamplerate?
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Disk-based Audio System
This sample-rate standard dates back to the days of
videocasettes.
Digital audio was stored in the scans
of a videoframe and a samplerate of 44.1KHz could
fit in both systems.
It was mathematically compatible with both European
PAL as the United States
standard NTSC film systems.
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Does Bitrate Really Make a Difference In My Music?
Lossy• MP3• WMA
Lossless• WAV• AIFF
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Digital Audio Format: Lossy Format
Both WAV & AIFF file are
uncompressed formats
They are exact copies
of the original
source audio.
The same quality; they just store the
data a bit differently.
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AIFF vs WAVAIFF is made by Apple, so you
may see it a bit more often in
Apple products
WAV is pretty much universal.
However, since they're uncompressed, they take up a lot of unnecessary space. Unless you're editing the audio, you don't need to store the audio in these formats.
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Digital Audio Format: Lossless Format
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MP3, FLAC, MWAMPEG Audio Layer III, or MP3 for short, is the most common lossy format around. So much so that it's become synonymous with downloaded music. MP3 isn't the most efficient format of
them all, but its definitely the most well-supported, making it our #1 choice for lossy audio.
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MP3, FLAC, MWAFLAC is Free Lossless Audio Codec with high audio quality and smaller file size. Therefore, it is quite popular with storing FLAC files with less space and better quality and many people have FLAC files.The popularity of
Apple devices like iTunes, iPhone, iPod, Apple Watch
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MP3, FLAC, MWAWindows Media Audio (WMA) is an audio data compression technology developed by Microsoft. The name can be used to refer to its audio file format or
its audio codecs. It is a proprietary technology that forms part of the Windows Media framework.
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Real Life Situation• Originally,
Microsoft claimed that WMA files had the same quality as MP3 files with half the size
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Real Life Situation• Independent
testing has disputed this claim, but WMA may still have slightly better quality than MP3.
So why convert WMA files to MP3?
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It is about compatibility
• The most important is compatibility.• Even though WMA is popular in Windows
programs, there are still many multimedia programs and MP3 players that are incompatible with this format.
• MP3, on the other hand, is so ubiquitous that almost any program or device will play it.
• Another reason to convert WMA to MP3 is if the file will be used on Mac-based software.
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• https://www.youtube.com/watch?v=sZBjWyyHoO0
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So why not 40 KHz you ask?
Common samplerates that are used nowadays can be a bit higher than 44.1
KHz.
Not only does this mean we
can theoretically record higher frequencies,
It also means we have much more samples that are
taken to represent our
audio.
Many operating systems and
audio interfaces
nowadays can support
sampling rates up to 96 KHz or even 192 KHz giving much
higher quality and processing
options.
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Good Tips!Working on higher sample-rates. There’s a number of reasons why we could chose to work with higher sample-rates and bit-depths when recording and mixing. • The first would be the better quality
and more dynamic range given at these higher sample-rates and bit-depths. This is much more pleasing to work with during mixing. KHz for surround material.
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Good Tips!Working on higher sample-rates. • Processing is much more accurate on higher
resolution material. Equalizing, reverbs, filters, etc.
• All sounds much better on higher sample-rate material. This is the reason why many plugins use so called ‘upsampling’ techniques to internally work at higher samplerates when processing audio.
• When you’re producing sound for DVD’s, which can handle samplerate’s up to 192 KHz on stereo material, and 96
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Here is a list of most common sample-rates found in the
industry.Samplera
te Usage
44.100 hertz Audio cd quality.
48.000 hertz Pro video, Dat audio, sampling rate of a lot of professional audio gear.
88.200 hertz Not often used doubling of the cd-quality, can sometimes be found.
96.000 hertz DVD audio quality supporting stereo-mixes up 5.1-surround-mixes.
192.000 hertz DVD audio quality supporting stereo-mixes.
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ReferencesMcGuire, Sam, and Roy Pritts. Audio Sampling: A Practical Guide. Burlington, MA: Focal Press, 2008.
Thompson, Daniel M. Understanding Audio: Getting the Most out of Your Project or Professional Recording Studio. Boston: Berklee Press, 2005.
Winer, Ethan. The Audio Expert: Everything You Need to Know about Audio. Waltham, MA: Focal Press, 2013.
Stanley, R Audio in Media 10th Edition. : Michael Rosenberg 2014
Audio Engineering Society (AES): www.aes.org
Audio Publishers Association (APA): www.audiopub.org
audio-tutorials/season-3-mixing/Episode-7-Digital-Audio-Sample-Rate-Bit-Depth.html
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Referenceshttp://audio-converter-software-review.toptenreviews.com/why-convert-wma-to-mp3-.html
http://lifehacker.com/5927052/whats-the-difference-between-all-these-audio-formats-and-which-one-should-i-use
http://www.digitalpreservation.gov/formats/fdd/fdd000027.shtml
http://whatis.techtarget.com/fileformat/WMA-Audio-file-in-Microsoft-Windows-Media-format