Question

IT-441: Multimedia Systems Development

Given an analog sound file, explain the major processes for digitizing that file. If the MP3 sound file format is used, explain how does it reduce the file size while maintaining the audio quality.

(Use your own words for answering)

Answer 1

Analog and digital sound:

1. Analog sound is the true representation of the sound at that particular moment or rather at that time,it was being recorded.
2. Digital sound is actually what we store in computer sound card or mobile,it is not the recording of actual sound,but we can say a combination of 0's and 1's that is binary code,which correctly represents the intensity and pitch.

Digitization of sound:

The process which converts the vibrations of sound into a digital/electrical signal is called as digitization.In more simple words we an say digitization of sound is the process of converting analog audio to digital audio.

Waveform ---->After Digitization---->Combination of 1's and 0's(binary code)

Processes involved in digitization of sound:

1. Firstly take that analog audio at predetermined time intervals which is called as sampling rate of sound.
2. To represent the sampled audio with digital signals,we use Pulse Amplitude Modulation(PAM).
3. Encoding signals into binary form(0's and 1's) involves Pulse Code Modulation(PCM) .This is required for processing in computers.

Let's get into deep about all above mentioned processes.

PAM:

Pulse amplitude modulation is one of the pulse modulation in which signal is sampled at regular intervals and each sample is made proportional to the amplitude of modulating signal

PCM:

A pulse code modulation(PCM) is atwo step process which involves,

• firstly the audio is sampled and represnted by digital signals.
• secondly the digital systems are encoded in binary format which is explained below.

Binary encoding of signals in PCM:

The integer numbers are converted into 0's and 1's that is into binary form.Finally the 1's and 0's now contain the audio information encoded in a form that is processed by a computer.

example:9=1001(in binary form).

Now the last part of your question:

The MP3 format is a lossy compressed audio format.It is compressed using lossy compression which reduces file size and reduces the sound quality to some extent but in most cases we don't experience any difference as MP3 is popular used audio format throughout the world.The main motive of mp3 sound is to cut out all the sound data which exists above the hearing range of most normal people and to ultimately reduce the quality of audio that aren't as clear to hear and then compress all other audio data as much as possible with the efficient way