Multimedia – Basic Text

Basic Text: Multimedia


The topics of ‘Basic Text Multimedia’ do not claim to exhaust the matters dealt with, since each would provide enough information to formulate a complete work, but provide a sense of working with multiple media complexities. This text can be used with the presentation to support teacher performance: Applying Media in Education.


The term multimedia was first used to describe the transmission of information using multiple media and various human senses. “In its broadest sense the term multimedia refers to the presentation or retrieving information that is made, with computer assistance, the multisensory way, integrated, intuitive and interactive.” (KEYS E., 1991).

According to Chaves (1991), the term multimedia, the feminine singular, seems to have acquired citizenship rights in Portuguese, – because the media word is included in Aurelio – as a translation of multimedia English term that in English, following the Latin, is plural ; although it seems a sense to use the singular after the multi prefix; concludes.

In the multimedia “presentation or retrieval of information is done in multisensory way, it is meant that more than one human sense is involved in the process, which may require the use of media that, until recently, were rarely employed in coordinated way “(KEY E., 1991) and integrated. What was done so far with the use of audiovisual feature was the presentation of information juxtaposed form, since only two senses were involved in the process, “leaving aside the tactile dimension of multimedia” (KEY E., 1991) because, with the help of the mouse, we like to “play” in the program that we are interacting.

This property has only been achieved thanks to the ability of the modern computer to store, process and transmit this information in a multisensory way, ie in the form of: sound, image, text, etc.

Multimedia allows

Presentation or recovery information multisensory way

In nature, most of the events we see is accompanied by a sound; for this we must use the sound as a powerful ally in getting the student’s attention. “With the ability of digital sound, we will have access not only to manifest powerful storytelling, but also to subliminal influences the effects of music” (LINDSTROM R., 1996).


The term tone refers to the acoustic phenomenon obtained by compression and expansion of the waveform, the particles of one medium – air, for example – it “spreads in all directions, for example, waves they form when we throw a stone in a calm lake “(LUTHER A., 1995). “When something moves in the atmosphere such as, for example, a string instrument or our vocal cords, moving air molecules” (LINDSTROM R., 1996) generating pressure variations. We hear these pressure variations, when they come to our ears. “Human ears are a type of sensor or transducer, for converting audible pressure variations in an electrical format used by the brain” (LUTHER A., 1995).

According Lindstron (1996) electronic equipment we use to capture manipulate and play sound, in essence, are similar to the human ear, because these variations convert pressure into electrical information.

To record an existing sound in nature use a transducer – a device able to convert one type of energy into another – to convert the kinetic energy of sound waves into electrical energy used by electronic equipment. The output of this process are the different levels of electrical voltage corresponding to different pressure levels change. “A microphone is a transducer example. Voltage levels, related to the analog signal, are then used to create a pattern on a magnetic tape. For playback, the tape signal is read by playback heads, amplified and goes to the speakers. The speaker is another type of transducer that performs the opposite conversion to the microphone. “(LINDSTROM R., 1996) The speakers convert different energy levels back into kinetic energy, recreating the original fluctuations in air pressure making the audible sound. (See Figure 1).

Figure 1 – Scheme of the recording and reproduction of sound process

We called the electronic sound audio signal. It “is measured in a two axes graph – voltage that varies with time” (LUTHER A., 1995) (Figure 1).

Chart 1 – Audio Signal

An audio signal is also composed of other parameters: amplitude, frequency and period – or wavelength. Amplitude is the pitch and is measured in decibels (dB). “The greater the pressure exerted by the moving object, the higher the sound and the higher the amount of decibel” (LINDSTROM R., 1996). In electronic systems the amplitude is the height of the wave, and “is measured by the maximum and minimum range of the audio signal voltage” (LUTHER A., 1995) (Figure 2).

Som - sinal de áudio

Chart 2 – Audio Signal

The second parameter to an audio signal is frequency. According Badgett et al. (1994) can imagine frequency as the quantity of waves passing a fixed point in a second. “Most audio signals varies periodically positive voltage to negative and back to positive again. The speed with which this occurs is called frequency intervals, and is expressed in cycles per second. The unit of frequency – one cycle per second – is called hertz (Hz) “(LUTHER A., 1995) (Figure 2). “The human ear can detect frequencies from about 20Hz to about 20,000 Hz to 20 kHz (20kHz)” (LINDSTROM R., 1996).

The third component of the audio signal is a period or wavelength. It is the distance between the peaks, or valleys, of adjacent wave. It is inversely proportional to the frequency – decreases when the frequency increases (Figure 2).

is adding to the personal computer some appropriate devices, it is able to process and beeping stored in files with proper structure that can be like, wave and midi.


The files wave (wave – usually with .WAV extension) are files obtained by scanning existing pre-recorded sounds or capturing sounds directly to your computer through special devices, for example, a microphone. “Scanning does the same thing to the sound it makes for text or any kind of information. It converts the information into numerical combinations that can be stored, retrieved and manipulated by computer “(LINDSTROM R., 1996).

According Lindstron (1996) for the audio signal digitalization changes its electrical values are converted to numeric representation by a device called an analog to digital converter (ADC – analog to digital convert) – which is a firmware. This numerical representation of the audio wave form can be converted back to an analog signal by a digital to analog converter (DAC – Digital to Analog Converter) for playback. (Figure 2).

ADC - DAC - Conversão analógico para digital e digital para analógico

Figure 2 – analog to digital conversion and digital to analog conversion

During the audio scanning the ADC digitizes both audio signal dimensions (voltage and time). “The time scale is converted to digital by a process known as sampling (sampling)” (LUTHER A., 1995) (Figure 3). To carry out the sampling, the ADC does instantaneous readings of the voltage at evenly spaced time. “Sampling frequency or rate is the number of samples read per second” (LUTHER A., 1995).

Amostragem - Sampling

Graph 3 – Sampling – Sampling

The output of this process is the sample flow corresponding to audio signal position at the time of sampling. According to Luther “we can imagine the samples as snapshots, because each is the exact picture of the voltage of the analog audio signal that existed at the time of sampling. At this moment the samples are converted into digital values in a process called quantization (Chart 4). The voltage range is divided by a number of levels or bandwidth – the exact number of levels depends on the number of bits determined for each sample. For example, if 8 bits are used to represent each sample, then the scale 256 will have levels (256 = 28) “(LUTHER A., 1995).

For example, the output audio signal of the scanning process shown in Figure 1, in a 4-bit Bandwidth – 16 levels (16 = 24) – with the sampling rate seen in Figure 3, would be the following flow bit: 0011011010101101111011011001010100100010010010001100111011101011.

The use of this technology allows you to use sounds in multimedia programs as: narrations, music, special effects, etc.


We can use the human voice scanned to explain a particular content or procedure, winning it a powerful ally as the narration being highly expressive serves to motivate the student through messages, and second Badgett, “the way we collect information is: 10 % of the words we hear, 40% of the way words are spoken and 50% of what we see “(Badgett T., 1994).


The use of appropriate music to the specific content produces interest and impact, because music helps create the climate necessary to provide a greater alignment and focus.


Special effects, such as: the sound of a door opening or the touch of a phone, increase user attention because we are used to hear the sound corresponding to the event that we witness.

Basic Operations for sound editing

a) Trimming

remove blank recording starts and unnecessary time the end of the recording, the menu of editing applications the most common commands for this activity are: Cut, Clear, or Erase Silence.

b) splicing and Assembly

For removal of strange noises

c) Volume Adjustments

To have a consistent volume within the entire recording. Do not use high volume, can distort the sound.

d) Format Conversion

Macintosh formats are the type SND and AIF, Windows is the type .WAV

e) Resampling or Dowsampling

To save disk space when using low frequencies or resolutions

f) Fade-Ins and Fades-Outs

Important to smooth the beginning or end of a sound

g) Equalization

It allows you to modify the recording rate to make the sound brighter or not

h) Time Stretching

More advanced programs allow you to change the size (in time) of the sound file without changing the music.

i) Digital Signal procesing (DSP)

Allows the creation of special effects such as vibration for example

j) Reversing Sounds

You can reverse all or part of the file. It might be interesting for a speech to be presented back to front.


This type of file “.MID” format allows you to store the instructions generated by digital electronic musical instruments MIDI (musical instrument digital interface). “This standard was developed in 1983 to allow digital electronic musical instruments, such as: synthesizers organs and drum machines to communicate with each other and with computers, regardless of their brands” (LINDSTROM R., 1996). Unlike the format .WAV files the .MID format is not composed of captured sounds of nature, but by statements like: a musical note was issued, by which means, for how long, at what time, etc. These data are read and synthesized – artificially created by the computer – generating the corresponding music.

This technology allows you to create smaller files that can be played indefinitely. Its main application is in the music storage.


The file format .MID shows all his potential to play instrumental music, because your files are relatively small – compared to .wav with the same quality – not overloading the system.


This file format does not present a good result for use with narrations, it would be necessary to determine the sounds themselves to faithfully reproduce the human voice, which would overwork and the result would be artificial.


The .MID generates very small effects files, but the sound is very artificial, losing in quality to .WAV.

static IMAGE

The computer allows the still or moving image archiving, treating them like any other data type, but modern computers allow showing these images on the screen with a quality, in our view, admirable.


Images that have no movement on the screen are static images called. “There are two basic types of treatment graphics (drawings, images, etc.): what is the image point to point and that is the image as vectors or objects.” (MEIRELLES F., 1994).

bitmap format files

This file format is structured in the form of a bitmap, where it transforms the image into a kind of dot matrix; the intersection formed by the intersection of the lines with the columns receiving the pixel name – elements picture of contraction -: in a standard VGA video monitor there is 640 columns by 480 rows for a total of 307,200 pixels. This “is a highly structured file that contains information about the type, size and color, as well as the elements of a picture image or pixels. Bitmap files can store images with photographic quality of all colors, but can also contain relatively simple pictures, masquerading as icons, buttons, sliders and other figures. ” (SWAN T., 1993).

digitalização de imagem

Figure 3 – Figure scanning

The scanner – “a practical device that ‘reads’ a page of text or graphic and send that information to the computer” (Gookin & MULLEN, 1994) – make the call scan picture, from left to right and from first to last line, reflecting the colors or grayscale pixel in electrical values, which are converted into a set of bits that correspond to a color or grayscale a table. This set of bits forms a pixel map of Fig.

digitalização de imagem

Figure 4 – Obtaining of pixels

For example, to scan Figure 3, a 1-bit color depth – two colors – and with a resolution of 8 lines x 10 columns, obtaining the pixel during the scanning process would be required as shown in Figure 4. The bit stream : 000000000100000000100000001
10000000100000000100000001100000001000000001000000000 which describes pixel is red (1) or yellow (0). The output of this process would resemble Figure 5.

digitalização de imagem

Figure 5 – Process Results

As noted, this type of file structure is not the most suitable for storage of geometric figures, drawings and maps.

Vector format files

Unlike the bitmap format files that store color information corresponding to each point of a matrix, vector files provide information objects making up the image, and “more suitable for images such as maps, charts, architectural drawings and other composite prints multiple and possibly overlapping layers “. (SWAN T., 1993).

For example, the file that would store Figure 3 would be greatly simplified, because besides the header with information about the file itself, contain information relating to the objects that compose it: the rectangle – size and color, and the diagonal line – coordinates start and end points, width and color. The computer reconstructs the image at the time to demonstrate it.



With the help of scanner or digital cameras can include photos in the application, which can tell stories, describe people, places or things and serve to capture the user’s attention.

The structure of the photo files are usually bitmap format, it would be almost impossible to create a vector file given its complexity.


In its broadest sense, in multimedia, graphics include almost everything that is seen on the monitor, except the videos. The graphics range from a static background which hosts the interactions to the use of color, through illustrations, photos, animations and use of titles and spreadsheets.


Some artistic images are not taken from nature but produced on the computer itself, through appropriate programs for this purpose. These images may have the two file structures seen before.

Motion pictures

One of the most powerful possibilities, in our view, the media is to add moving images. Lindstrom drew attention to this when he said: “We live in a dynamic world – a movement of world. Even when you sit in a room where nothing moves, you can still change the perspective by moving your chair, your head or even just your eyes. You are, in a way, the film director (and editor) what you see. ” This feature allows us to attract the interactor’s attention to the point of the need to screen at the right time, to emphasize text or events, or demonstrate phenomena, procedures or any things that we deem necessary.

We can get these animations through exposure and concealment of successive still images, using this programming of our own application or can import files containing animations.


As with the sound recording, digital technology allowed convert videos from analog format to digital. This technology has made possible the use of scenes from movies or documentaries multimedia programs.

According Lindstron, digital video is stored by the computer as a binary code, like any other type of information, a photograph, for example. “The difference, however, is that the video image is based on timing. Video frames – each being a separate image – should be played in a steady and rapid speed to achieve the illusion of movement. ” (LINDSTROM R., 1996).


The analog video may be digitized using appropriate hardware and software or using appropriate chambers, it can be directly captured in the digital format.


We call animation any form of movement seen on the screen, which can range from a simple screen transition to the construction of a complex animation as a flying bird, through the direction on the screen of a moving object by a pre track -defined.

Three-dimensional animation

Calls 3D animations are a powerful tool to be used in multimedia programs, especially educational, they allow the modeling of objects by adequate programs and perfect control of these objects in the animation. Using this technique it can realistically demonstrate to students concepts or facts that would be impossible otherwise.


“The morphing effect is known as a technique in which an object gradually transformed into another. This technique has become very popular in movies, television and commercials. ” (ELLIOT et al, 1994) Using an appropriate program provide two images – the initial and the final – with the same technical characteristics; after we select some points one and move these points in the other, the program will generate a series of intermediate frames that give the impression that the first object is turning the other.


Written words are descriptive, detailed and direct, as highlighted Lindstrom (1996), however, the computer screen is not the most suitable place for reading, because the screen resolution is undeniably smaller than the resolution of the printed media. The use of scroll bars are, in our view, unpleasant, turning the pleasure of reading a sacrifice, for the light directed directly to the view makes the tiresome reading when compared to indirect light on the printed page. However, it was necessary to adapt this undeniably powerful way of transmitting information to the environment of multimedia.


Use short paragraphs – never larger than the screen – not wordy or dense – saying what must be said and only what must be said – in the proper location, as well as the use of markers and short words have shown to be more attractive .

Mapping Information.

According Romiszowski (1995), the mapping information is a process of preparing information maps; It consists of a set of rules to analyze, write, organize and present any information.

Romiszowski (1995), cited in demo, “said Robert Horn, the developer of this technique, information mapping … is a method of organizing information categories and present them both with reference purposes and for learning … The procedures and rules to map information were derived from educational research and technology and the world of communication. The emphasis is on formats to quickly communicate exploitation and data recovery. ” (Horn et al 1969).

For the application of this technique the writer must select the text blocks functional information – which are paragraphs whose information they bring, are self-sufficient – then must determine what fundamental kind of information they belong – if the contents of this block this is a concept, or an example, or a procedure or process, or even a flow chart, etc. – Then, among other measures, it must assemble the map taking care to indicate that fundamental class information they belong blocks.

The use of this technique in the preparation of study aids allows a non-linear reading, it is the player who chooses the logical sequence, as far as delving, what exercises to do, etc.

“The structure of a booklet prepared by this technique is similar to a geographical atlas, in the sense that there are pages which present a summary total (such as a world map), and other pages that explain each piece of information with more details (such as maps continents, countries, regions, cities) (Romiszowski A., 1995)

With minor adjustments, the information mapping proved to be an effective technique in the preparation of short, clear, understandable and self-explanatory texts, it provided them with powerful properties: the ease of recovery of the texts, the ability of the student to delve into a topic following their curiosity and the ability to find the object of quickly and efficiently search.


According to Horn (1989), the term hypertext was first used by the researcher Nelson, T. 1965; in his article, the researcher predicted that in the future all documents created by man would be the abeam links (link), contained in a single text. Today the term is used to describe interactive documents. According to the word morphology hyper prefix gives the word text a notion of ” superior ‘position; ‘beyond’; ‘Excess’ “(FERREIRA A., 1994) or, simply put, a gigantic text.

In practice, hypertext is a system of interconnected texts that allow students to read a personalized issue, and sent the new text when you click on Hotword (hot words) – an object made by one or more words that can respond to an event mouse or keyboard – which are previously marked in the text. (Figure 6).

Figure 6 – Schematic representation of hypertext


Hypermedia is an extension of the concept of hypertext, as well as linking the texts through Hotword interconnects also new media, such as: pictures, sounds, movies, etc. (Figure 7).

Figure 7 – Schematic representation of hypermedia


The interaction is reason to exist multimedia. It is the property of an application that “allows the user to ask questions and then direct the flow of the program” (Badgett T., 1994). Lindstron said that “the power of interactivity lies in the ability of all parties to express their interests and communicate their concerns” (LINDSTROM R., 1996).


As we alluded to in the introduction, to begin the research, our great uncertainty was whether the computer could be used as a tool for teaching geometric design, in view of the teacher’s difficulty in assessing an exercise, since there is no standard resolution. In Geometric Design exercises should be interpreted in the time of evaluation, as each student can reach the right solution, often in different ways. In our view then, the computer could only solve multiple choice questions. It was a great challenge!

We began to research the possibilities of Informatics and started to produce a graphical environment that resulted in the “Virtual Clipboard”. After this stage, we began to research the possibility of this program will not only be an exercise building environment, but also be able to examine whether these exercises would be correct. We achieved a consistent result with the binary logic offered by the authoring software used, and compatible with our commitments, but short of the wishes of the computer evaluate the exercise. That is, the system checks if it was created an object with the characteristics of the desired geometric entity, however, in case of error, do not know what is wrong or if correct, does not know if the expected result was achieved following the proper procedures the classical solutions Geometric Design. This solution was implemented by judge be motivating for the student, because it will get a response from the computer increasing their interaction with the program.

In parallel, We Searched how to use the computer’s potential to teach the concepts of geometric design. One of the investigated techniques, which proved very successful, was the mapping information, as provided in short and clear texts. Another technique was the 2D animation that allowed us to demonstrate the classic procedures for solving geometric problems, and also run the tutorial. Moreover, the animation technique in 3D enabled display in the space of examples of subjects treated; comparison, through transformations of geometric entities in objects of day-to-day; learning the proper use of drawing materials in obtaining the geometric entities; clarify any doubts by demonstrating counterexamples; always taking care to see if the student is mastering these concepts through conceptual exercises or procedures. All this was done with the utmost care not to preen with technology, not making the technique would compete with the stated issues, but always looking to leave the attractive work.

During the work, we take care to adopt a number of technical limitations, because we developed to meet the public schools, the vast majority have smaller capacity machines. As a result we obtained a lower aesthetic quality program, however, not neglected the quality of content and texts.

Depending on the technical limitations of the resolution of video monitors, we developed a way to increase the accuracy for the solutions of the exercises, since the succession of errors compromise the quality of the year, leading the program to interpret it as wrong. To this end we developed a routine that draws the cursor at intersections of rows, thus ensuring that the student always click the appropriate point.

We spare no efforts to run a complete hypermedia program, so that it is twenty-five subjects divided into one hundred seventy-four pages, has two hundred and seventy 3D animations, twenty six technical procedures, thirty-one years , tutorials, narrations, glossary, hypertext, help, etc. Our effort seems to have been well accepted in academia as invitations to present it on several occasions are numerous, and the program was awarded a prize awarded by the Ministry of Education and Sports.

The techniques researched during this period proved to be quite effective for the production of interactive educational programs, but also in the preparation of lectures, because they add a new dimension – out of conventional chalk picture plane – to matters covered by the teachers in the room class, serving as a powerful tool for these professionals.

Eduardo Stefanelli

Engenheiro por profissão, professor por vocação

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