T2 - Sound + Compression Flashcards

1
Q

Analogue sound signals are which type of data

A

continuous.

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1
Q

Digital signals are which type of data

A

discrete.

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2
Q

How Sound is digitized:

A

by repeatedly measuring + recording the sound wave

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3
Q

A to D converters:

A

Sounds is converted to a digital form
= stored + processed by a computer

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4
Q

An Analogue to Digital Convertor (ADC) is used for

A

to convert inputs to digital signals.

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5
Q

A Digital to Audio Convertor (DAC) is used for

A

to convert digital signals to outputs.

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6
Q

Sound sampling -

A

measurement of amplitude of a
sound wave at a given time

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7
Q

How is sound sampled:

A
  • Sound is sampled using a bit depth and sample rate
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8
Q

what does bit depth determine in sound sampling

A

determines how closely the wave is sampled on the y-axis

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9
Q

Sampling rate -

A

number of samples taken per second
(Hz)

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10
Q

Sample resolution:

A

The number of bits used to record
each measurement

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11
Q

More bits used per sample =

A
  • the height of the wave to be more accurately measured
  • increases file size
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12
Q

Hertz

A
  • 1Hz = 1 sample per second
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13
Q

sample resolution aka

A

audio bit depth

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14
Q

Sampling rate frequency:

A

The greater the frequency, the greater the accuracy, and file size

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15
Q

Calculating sound file sizes:

A

sample rate * bit depth * duration

16
Q

Recording quality improves: as a result of

A

the more frequent
the more accurately recorded the wave height

17
Q

Increasing the sampling rate (frequency) =

A

means recording more data points

18
Q

Increasing the bit-rate =

A

improves the accuracy of each data point

19
Q

Lossy compression:

A

removes sounds that
we can’t easily hear or that is unnecessary

20
Q

Lossy compression cons:

A

-leaves out some data
=affects quality

21
Q

Lossy compression pros:

A

useful for storing,
downloading or streaming
-as it is smaller

22
Q

Lossless compression:

A

-reduce the file size
when compressed but do not
lose any information
-can be decompressed

23
Q

Eg of lossless:

A

FLAC (Free Lossless Audio Codec)
ALAC (Apple Lossless Audio Codec)
WMA Lossless (Windows Media Audio)

24
Q

Uses of compression:

A

often used for files and data that are sent via the internet
Download times are reduced
Data allowances go further
No lagging

25
Q

Benefits of compression: (6)

A
  • Smaller files = fewer packets = faster transmission time
  • Quicker to complete transmission
  • Reduces traffic over the Internet
  • Reduces download times
  • Images inside web pages appear faster
  • Reduces space on disk / servers
26
Q

no lagging means

A

= transmission of
video + music data streams as fast as they are playing