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INTRO TO MULTIMEDIA

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Chapter #3

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INTRO TO DIGITAL AUDIO

DAC : Diagital Analog Converter.

ADC : Analog Digital Converter.

Sampling Rate: The number of samples we take persecond. (Hz).

Digitization: Process of assigning discrete value to each ofthe sampled values.

Fidelity: The closeness of the recorded version to the

original sound.2

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Mono Recording: (1 Channel)

File size = Sampling rate x duration of recording in seconds x (bits per sample/8) x 1

Stereo Recording: ( 2 Channels)

File size = Sampling rate x duration of recording in seconds x (bits per sample/8) x 2

SOUND FORMATS & SETTINGS

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Q) What will be the size in MB of 30 seconds

recorded sound, whose Sampling Rate is 11 kHz & bitresolution is 16 Bits. ( in Mono Recording ).

A) F.S = 11 khz x 30 seconds x 16/8 bit.= 11 k/s x 30 s x 2 bytes

= 660 kb* 660 1024 = 0.6 MB

*Hz = 1/s

* kHz = k/s = 1000/s

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Q) What will be the size of 2 minutes recordedsound, whose Sampling Rate is 1000 Hz & bitresolution is 16 Bits. (in Sterio Recording)

* F.S = S.R x Time x B.Time= F.S.

S.R x B

(120 seconds)

( 1 kHz )

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COMPRESSION

Compression: Reducing the physical size of data suchthat it occupies less storage space and memory.

Common Compression Methods :- An array of compression techniques have been set by the CCITT group-aninternational organization that develops communication standards known asRecommendations for all digitally controlled forms of communication.

There are 2 types of compression:

1.Lossless Compression. (we never lose data)

2.Lossy Compression. (we lose data)

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Lossless Compression:

- This compression technique is used for textdocuments, databases, and text-related objects.

Lossy Compression:

- There is loss of some information when lossycompression is used. Its the most commonly usedcompression. Its used for images, audio and video.

COMPRESSION TYPES

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END OF CHAPTER 3

(= Rahma Alhajri =)

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