Text, audio, video, graphics and animation

Hello students, welcome to Kwickprep. Why is a song file small, but a movie file huge? The answer lies in how each multimedia component is stored. Today we study text, graphics, audio, video and animation in detail, with their types and file formats.

Let us start with text. Text appears as headings, labels, menus, subtitles and captions. A font is the style of the letters, like Arial or Times New Roman. Serif fonts, like Times New Roman, have small strokes at the ends of letters, while sans serif fonts, like Arial, do not. Hypertext is text with links that take you to other content, like on a website.

Text is saved in different file formats. Plain text files end in txt and hold only characters, with no styles. Rich Text Format files end in rtf and keep bold, italics and fonts. Word processor files end in docx or odt. PDF files keep the page layout fixed, so they look the same on every device.

Graphics are of two types. A bitmap image, also called a raster image, is made of pixels, which are tiny coloured dots. When you zoom in a lot, the dots show and the image becomes blurry. A vector image is stored as lines, curves and shapes, using maths. So it stays sharp at any size, which suits logos.

Here are common graphic formats. JPEG is a bitmap format that makes photographs small in size. PNG is a bitmap format that keeps sharp edges and supports transparent backgrounds. GIF is limited to two hundred fifty six colours and can hold tiny animations. BMP stores images without compression, so files are big. SVG is a vector format, used for icons and logos on websites.

Two words decide the quality of a bitmap image. Resolution is the number of pixels, written as width by height, like nineteen twenty by ten eighty. More pixels give more detail, but a bigger file. Colour depth is the number of bits used to store the colour of one pixel. Twenty four bit colour can show about one point six eight crore colours.

Now audio. Sound travels as a wave, but a computer can only store numbers. So it measures the wave again and again, and this is called sampling. The sample rate is how many times it measures each second. Music CDs use forty four thousand one hundred samples every second. A higher sample rate gives better sound, but a bigger file.

Audio also has many formats. WAV files are usually uncompressed, so they sound best but are large. MP3 files are compressed by removing sounds we hardly hear, so they are small, and this is called lossy compression. AAC is similar, and phones and streaming apps use it. MIDI files do not store recorded sound at all, only instructions like which note to play.

Pause and predict. A three minute song saved as WAV is about thirty megabytes. We save the same song as MP3. Will the file be bigger, smaller, or the same? It will be much smaller, around three to seven megabytes, because MP3 removes sounds we hardly hear.

Next, video. A video is many still pictures, called frames, shown quickly one after another. The frame rate is the number of frames shown each second, written as fps. Cinema films use twenty four fps, and many phones record at thirty fps. Common video resolutions are HD seven twenty p, Full HD ten eighty p, and 4K.

Video files come in several formats. MP4 is the most common, used by phones and YouTube. AVI is an older format made by Microsoft for Windows. MOV is the format used by Apple devices. MKV can hold many audio and subtitle tracks, so it is used for movies.

Now we can answer our opening question. One second of Full HD video holds thirty large pictures, plus sound. That is why video files are the largest. Compression shrinks them by storing only what changes between frames. A codec is software that compresses video and opens it again for playing. A very common codec is H.264, used in most MP4 files.

Finally, animation. In animation, each picture changes only a little from the last one. Our eyes hold an image for a fraction of a second, which is called persistence of vision, so fast pictures look like motion. An animator draws keyframes, which are the main start and end positions. Tweening means the computer creates the frames in between automatically.

Animation comes in different types. Two D animation is flat, like cartoon shows on television. Three D animation has depth, and is made with modelling software, like modern animated films. Stop motion moves real objects, like clay models, a little in each photo. GIF animations are short loops, used as stickers on websites and chat apps.

Let us compare all five together. Text does not move, and uses formats like TXT and PDF. Graphics are still, and use JPEG and PNG. Audio is sound only, stored as MP3 or WAV. Video moves, and is recorded from real life, usually as MP4. Animation also moves, but it is created, and is saved as GIF or MP4.

Let us revise what we learned today. Text uses fonts and hypertext, saved as TXT, RTF or PDF. Bitmap graphics blur on zooming, but vector graphics stay sharp. Audio is stored by sampling, and WAV is big while MP3 is small. Video is measured in frames per second and compressed by a codec. Animation uses keyframes and tweening. Check the formats of files on your own phone today.