Multimedia Elements: Sound, Animation, and Video

Objectives w Describe the sound, animation, and video elements that make up multimedia w Specify the tradeoffs involved in using these elements w Specify the advantages and disadvantages of using these elements w Describe the programs used with these elements

Multimedia Elements: Sound, Animation, and Video 3 Chapter Outline w Sound Sampling MIDI w Animation w Video Digitizing Compression

Multimedia Elements: Sound, Animation, and Video 4 Sound w Volume: height of peak w Frequency: distance between peaks, measured in hertz (Hz) Volume Frequency

Multimedia Elements: Sound, Animation, and Video 5 Sampling w A digital representation of a portion of the sound is made every fraction of a second. w Sample rate: how often is the digital representation made? w Sample size: how large (# of bits) is each digital representation? Number of bits used for each sample or, the number of quantization levels

Multimedia Elements: Sound, Animation, and Video 6 Sample Rate w Common sample rates kHz kHz 44.1 kHz w The more samples, the more accurately the sound is represented w The more samples, the larger the file size

Multimedia Elements: Sound, Animation, and Video 7 Sample Size w Common sample sizes 8 bit: 256 possible values 16 bit: 65,536 possible values w The larger the sample size, the more accurately the sound is represented w The larger the sample size, the larger the file size

Multimedia Elements: Sound, Animation, and Video 8 File Size w 1 second = sample rate x bit value / 8 w Stereo doubles the size w CD quality: 44.1khz 16 bit sample w Stereo CD-quality file size: 176,400 bytes per second

Multimedia Elements: Sound, Animation, and Video 9 Sound Card w Used to digitize sound w Accepts analog input from audio source w Samples according to specified sample rate and sample size w Produces digital representation of the audio signal

Multimedia Elements: Sound, Animation, and Video 10 Sound Editing Programs w Digital representations can be easily manipulated w Cut and paste w Sound effects (echo, fade-in, fade-out, etc.)

Multimedia Elements: Sound, Animation, and Video 11 MIDI w Musical Instrument Digital Interface w MIDI files Coded events (such as note pitch and duration) Series of instructions that can be followed by any MIDI-capable musical instrument Another way to incorporate sound into multimedia titles

Multimedia Elements: Sound, Animation, and Video 12 MIDI Compared to Digital Audio w Digitized audio begins with a sound, samples it, and creates a digital representation which is stored in a file. w MIDI begins with an event, such as pressing a key on an electronic musical instrument such a s MIDI keyboard, and code the event (including which key and how hard and long it was pressed) as a series of commands.

Multimedia Elements: Sound, Animation, and Video 12 MIDI Compared to Digital Audio w Advantages because it represents the notes along with information as volume and frequency More precise editing is possible File sizes are much smaller w Disadvantages Only MIDI-capable instruments can send MIDI instructions Only MIDI-compatible playback devices can be used

Multimedia Elements: Sound, Animation, and Video 12 MIDI Compared to Digital Audio w Requires specialized software w A MIDI compatible audio card w Special equipment with MIDI interface

Multimedia Elements: Sound, Animation, and Video 13 Animation w Consists of a series of images, each in its own frame w “Jerkiness” occurs when fewer than 12 frames per second (fps) are displayed

Multimedia Elements: Sound, Animation, and Video 14 Types of 2-D Animation w Cel animation w Path animation

Multimedia Elements: Sound, Animation, and Video 15 Cel Animation w ‘Cel’ comes from the word ‘celluloid’ w Objects move against a fixed background

Multimedia Elements: Sound, Animation, and Video 16 Path Animation w Objects move along predetermined path w Path specified by mouse dragging or by clicking on intermediate points w Tweening is a technique used to fill in the path between predetermined points

Multimedia Elements: Sound, Animation, and Video 17 Steps in 3-D Animation w Modeling w Animation w Rendering

Multimedia Elements: Sound, Animation, and Video 18 Modeling w Process to create 3-D objects and scenes w Points are set in a grid to define the object’s shape

Multimedia Elements: Sound, Animation, and Video 19 Animation w Specify the object’s motion w Specify how lighting and views change as the object moves

Multimedia Elements: Sound, Animation, and Video 20 Rendering w Apply colors, textures, and transparency to objects w Takes a substantial amount of time

Multimedia Elements: Sound, Animation, and Video 21 Animation Special Effects w Morphing: transform one image into another in a series of frames w Warping: transform aspects of a single image in a series of frames

Multimedia Elements: Sound, Animation, and Video 22 Virtual Reality w Attempts to create an environment that “Surrounds” the user so that he or she becomes part of the experience w Useful for simulations, games, and educational applications w Requires that the user have a high-end computer

Multimedia Elements: Sound, Animation, and Video 23 Digitizing Video w Video source is connected to video capture card in the computer w The card converts the video signal to a digital file stored on the hard drive

Multimedia Elements: Sound, Animation, and Video 24 Advantages of Digital Video w Easier to edit w Adding special effects is easier

Multimedia Elements: Sound, Animation, and Video 25 File Size Considerations w Frame rate: 15 fps (low quality) to 30 fps (TV quality) w Image size: 320 x 240 (1/4 screen) to 640x480 (full screen) w Color depth: 8 bits (256 colors) to 24 bits (16 million colors) fps x image size x color depth / 8 = file size per second

Multimedia Elements: Sound, Animation, and Video 26 Video Compression w Codec: compression/decompression programs w Lossless compression: exact image is retained w Lossy compression: some information about the image is lost

Multimedia Elements: Sound, Animation, and Video 27 JPEG Compression w JPEG: Joint Photographic Experts Group w File size is reduced by removing redundant information w Similar neighboring pixels are stored as a block of pixels w 20:1 compression possible

Multimedia Elements: Sound, Animation, and Video 28 MPEG Compression w MPEG: Motion Picture Experts Group w Includes still-image compression w Also removes redundant information between frames w Requires special hardware

Multimedia Elements: Sound, Animation, and Video 29 Software for Capturing and Editing Video w Some packages permit capturing, compressing, and editing video w Common editing features Fast access to any frame Transitions Titles Sound-video synchronization Filters

Multimedia Elements: Sound, Animation, and Video 30 Key Terms w Analog wave pattern w Animation w Cel animation w Codec w Frames per second (fps) w Frequency w Hertz (Hz) w JPEG w Lossless compression w Lossy compression w MIDI

Multimedia Elements: Sound, Animation, and Video 31 Key Terms (continued) w Modeling w Morphing w MPEG w Path animation w Rendering w Sampling w Sound card w Tweening w Virtual reality (VR) w Volume w Warping