This document discusses key concepts in digital audio including sampling, quantization, digital recording, and disk-based audio systems. It explains that sampling is taking parts of an existing music piece to create a new production. Quantization refers to capturing amplitude values during sampling. The document also discusses sample rates, bit depths, lossy and lossless audio formats like MP3, WAV, and FLAC. Common sample rates used in the industry like 44.1 kHz and 48 kHz are also outlined.

1. Digital Audio &
Technology Application
Sampling
Quantization
Digital Recording
Reproduction Process
Disk Based Audio System
By Azmawati Binti Mohd Lazim | azmawati@mmu.edu.my

2. 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.

3. What is sampling?
which is
taking
'samples'
(or parts)
of an
existing
music-
piece
and using
that to
create a
new music
production.

5. 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.

6. Nyquist Theory
• FS = 2 x FN
• FS=Sampling frequency
• FN=Nyquist frequency

7. What is quantisation?
Sampling is capturing an amplitude value in time.
This value is captured in a process called
quantisation

8. • 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.

9. Reproduction Process
The 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.

10. 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.

11. Digital Recording
44.1 KH
samplerate?

12. 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.

13. Does Bitrate Really Make a
Difference In My Music?
Lossy
• MP3
• WMA
Lossless
• WAV
• AIFF

14. 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.

15. AIFF vs WAV
AIFF 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.

16. Digital Audio Format:
Lossless Format

17. MP3, FLAC, MWA
MPEG 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.

18. MP3, FLAC, MWA
FLAC 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

19. MP3, FLAC, MWA
Windows Media Audio (WMA)
is an audio data compression
technology developed by
Microsoft. The name can be
used to refer to its audio file
format orits audio codecs. It is a proprietary
technology that forms part of the Windows
Media framework.

20. Real Life Situation
• Originally,
Microsoft
claimed that
WMA files had
the same
quality as MP3
files with half
the size

21. 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?

22. 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.

23. • https://www.youtube.com/watch?v=sZ
BjWyyHoO0

24. So why not 40 KHz you
ask?

25. 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.

26. 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

27. Here is a list of most common
sample-rates found in the industry.
Samplerate 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.

28. References
McGuire, 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

29. References
http://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