1. Multimedia Fundamentals(continued)

2. Multimedia Fundamentals
Audio
realistic sound: is produced by the vibration of matter. During the vibration, pressure variations are created in the air surrounding it. The pattern of the oscillation of an air pressure wave is called a waveform.(Figure: continuous waveform)

3. Figure: continuous waveform

4. Multimedia Fundamentals
Computer representation of sound:
The smooth, continuous curve of a sound waveform is not directly represented in a computer. A computer measures the amplitude of the waveform at regular time intervals to produce a series of numbers. Each of these measurements is a sample.(Figure: digitally sample waveform)

5. Figure: digitally sample waveform

6. Multimedia Fundamentals
Sampling Rate
The rate at which a continuous waveform is sampled is called the sampling rate. Like frequencies, sampling rates are measured in Hz. The CD standard sampling rate of Hz means that the waveform is sampled times per second.

7. Multimedia Fundamentals
Quantization
Just as a waveform is sampled at discrete times, the value of the sample is also discrete. The resolution or quantization of a sample value depends on the number of bits used in measuring the height of the waveform. An 8- bit quantization yields 256 possible values; 17-bit CD- quality quantization results in over values.(216=65536)
the space of 4 minutes CD-quality song: (4×60×44100×17)/8=22.5MB

8. Multimedia Fundamentals
MP3 compression
The MP3 format is a compression system for music. The MP3 format helps reduce the number of bytes in a song without hurting the quality of the song.
the norm for music today-typically compress a CD-quality song by a factor of 10 to 12 while still retaining CD-quality sound.

9. Multimedia Fundamentals
Digital photograph
8 Million pixels bits color (the total space of the picture would be 24MB)

10. Multimedia Fundamentals
Summary
computer graphics
computer animation
audio
digital photograph