2.4 Sound/Audio Representation

	Sound is a physical phenomenon produced by the vibration of matter and transmitted as waves.
	Sound waves can be characterized by the following attributes: period, frequency, amplitude, bandwidth, pitch,
	loudness, and dynamic.
	Sound waves are continuous signals. These signals have to be converted to a digital form to be used by
	computers. Nyquist sampling theorem states that the sampling rate must be at least twice as high as the
	highest frequency you need to represent.

Audio file types

The following are the common audio file types:

		.wav: The wav format is the most common sound format file in Windows operating system.
		.mp3: The mp3 format is stands for MPEG (Moving Pictures Experts Group) audio layer 3. It has a good
		compression rate with perceivably high quality sound.
		.mov: It is created originally by Apple. It has a variety of sound compressors and files can be streamed.

2.4 Sound/Audio Representation

MIDI: Musical Instrument Digital Interface

	MIDI is a protocol that enables computers, synthesizers, keyboards, and other musical devices to
	communicate with each other.
	Synthesizer is a sound generator with various pitch, loudness, and tone.
	Different synthesis can be used to make sound.
	Synthesizer often has a microprocessor, keyboard, control panels and memory.
	It has one or more MIDI INs and MIDI OUTs and/or USB connectivity.
	The sequencer is a software program that has one or more MIDI INs and MIDI OUTs and/or USB connectivity.
	The MIDI system has a computer that controls the scheduling, synchronization and recording of all data.
	Hardware aspects of MIDI: The MIDI setup has the following pins:

		MIDI IN: the connector via which the device receives all MIDI data.
		MIDI OUT: the connector through which the device transmits all the MIDI data it generates itself.
		MIDI THROUGH: the connector by which the device echoes the data receives from MIDI IN.

2.4 Sound/Audio Representation

Structure of MIDI messages: There are two types of MIDI messages which are:

Channels messages:

			These messages are transmitted on individual channels.
			The receiving instrument is instructed to assign particular sounds to its voice.
			Then, alter the sound of the currently active note or notes.

System messages:

			These messages carry information that are not channel specific such as timing signal for
			synchronization, positioning information in pre-recorded MIDI sequences, and setting up sounds,
			sPatch Names etc.