 Hello friends, Myself Ilya Arsandane, Assistant Professor from Department of Electronics, Valchen Institute of Technology, Sallapur. Today we are going to see the topic Levels of Digitization and the term M.I.D.I. This deals with the subject which is known as Audio Video Engineering. So, basically what are the learning outcomes? So, at the end of these topics, you will be able to understand the different levels of digitization. Also, the students can able to illustrate the different formats of sound audio which are used in recording and reproduction and then the term what is meant by M.I.D.I. So, first we will see Levels of Digitization. The major levels of digitization of a sound are sampling and quantization. So, basically what is meant by sampling? Here sampling is nothing but conversion of sound waves into digital one. This is done by using a periodic signal which is nothing but a sound or an audio. First, this signal is analyzed for the sampling process and then samples are taken by using the equation as xn is equal to x of nt where t is the sampling period and the opposite transformation is done by using x of n tends to x of t which is also known as interpolation method. Generally, the sampling depends on the Nyquist rate which is given by the formula as fs is greater than or equal to twice of fm where fs is the sampling frequency and fm is the maximum frequency. Here fm is nothing but the maximum frequency this deals with the sound or the audio signal. Nextly, the next level of digitization is the quantization method. Here, the quantization is done by using the equation as x of n is equal to q x of n where q is a function which is known as rounding of function which maps the value of x of n which is a real number into the value of n levels which are the integers and these n levels are generally the samples which are taken from an audio signal. So, quantization generally this maps each sample to the nearest value of n levels vertically hence this is done by using the rounding up also we must know the quantization error this is generally defined as the difference between actual value of analog signal and nearest quantization intervals here in the diagram you will come to know the difference between the sampled and the quantized level here the figure a generally shows the samples which are taken at different time intervals here input is the frequency and output is the and the output is nothing but the time period here this generally shows the staircase type of the waveform but by using the quantization process the step size is increased that it that means here we can say that the during the quantization process each sampled is mapped to its nearest value of the integer or the samples taken in a vertical manner hence you will come to know the difference here at the vertical position is different in this figure b here the vertical position of the staircase is exact as that of the samples taken for the for the quantization process. Nextly the quantization generally uses PCM type of modulation technique whereas PCM is known as pulse coding modulation type of a technique in this bits per samples which are taken are of 8 or 16 bits. Nextly when the levels of digitization is done by using sampling and quantization process editing of digital audio signal is done so this is basically done by the below steps first the different trimming and splicing and assembling type of process takes place where trimming generally takes place for the unwanted part splicing generally takes place for the removal of the noise and assembling that means after these two process that is trimming and splicing assembly of the total audio signal takes place. Nextly volume adjustments are done for the low pitch and the high pitch of the sound similarly format conversions are done depending upon the different OS resampling and or down sampling is done during the reproduction of the sound fading and fadeouts are generally done at the noise different noise level where the fading and fadeouts are done at the different noise level where the noise is high or noise is low equalization is maintained between between the high pitch and the low pitch also the synchronization is maintained between the audio as well as the video. Generally time stretching takes place wherever the time needs to be extended. Nextly digital signal processing and reversing of sound generally deals with the reproduction of the digital audio signal in this way editing of digital audio signal is done. So what are the different audio formats so basically the different audio formats generally these depends upon the type of OS we are using first AIFF that is audio interchange file format this is generally used for SOU type of McIntosh type of operating system next second format is .WAV that is waveform audio this file format is generally used for Windows or Microsoft. Nextly .VOC that is voice recorder these are generally used for sound blaster cards. So what is meant by the term MIDI so basically the full form of this is musical instrument digital interface here the MIDI is a standard which is used for specifying a musical performance. So here basically the process takes place in this manner some raw digital audio is sent to the MIDI then the MIDI gives the performer some instructions as to how to play the instrument what should be the volume and what should be the sound of that particular instrument also which note to be played for that particular digital audio. Nextly if we can take the example of synthesizer the synthesizer when interfaced with MIDI the MIDI gives the synthesizer the actual notes different volumes and sounds which are to be played during the playing of a keyboard piano. Nextly MIDI sequences so generally the MIDI sequences are the instruments which are generally used or we can say it is a software which is which is used by the different musicians to edit and to create musical compositions which is done by using cut and paste method and insert and delete method. So this is the MIDI sequencer type of a software which is generally used for the by the musical composers for editing deleting and for enhancing the audio or a sound signal. So we will take a look now between the difference between MIDI versus the .AWAV. So here quality of recording this is the first parameter generally this the generally this depends upon the MIDI whereas in .WAV it is easier to it is easier to create than the MIDI. The MIDI has advantages as such file size is smaller size as the size is smaller the storage required for storing MIDI file is less. Nextly MIDI has disadvantages that playback should be done again and again and next the cost of the particular software is high and we require some skilled person to use the MIDI software. So summary there are two types of two main types of digital audio first sampled audio which is firstly captured then it is analog which is then converted into the digital by using the sample sampling process and data rate is set secondly MIDI data here some instructions are given on how to perform some musical compositions by using different instruments and sampled audio requires more storage than the MIDI informations. So students these are the assignments first discuss the different levels of digitization second list out the different audio formats and thirdly discuss the term MIDI. So these are the references by which you can solve the assignments and the you can have the data for solving the assignments. Thank you for watching the video.