Video Data dan Teknologi Multimedia Sesi 06 Nofriyadi Nurdam
Learning Outcomes At the end of this session, the students will be able to: • Show how to use video on multimedia application.
Course Outlines • Analogue Video • Digital Video • Video Manipulation • Standard Broadcast Video • Working with Video
Different Kind of Movies Movies from Film Analog Video Digital Video
Movie From Film Sequential image frames are recorded on film using a light sensitive technology similar to still photography. Film must be chemically developed
Movie From Film Editing requires physically cutting and splicing the film
Analogue video • Video information that is stored using television video signals, film, videotape or other non-computer media • Each frame is represented by a fluctuating voltage signal known as an analogue wave form or composite video. • Composite analogue video has all the video components: brightness, colour and synchronization • Then, combined into one signal for delivery • Usage : television • Problems: colour blending, low clarity, high generation lost, difficult to edit
Analogue video editing Analogue tape editing is a linear process To find the section you want, you may have to forward or rewind the video tape To move a section to another place in the sequence you have to either re-record the section onto another tape or physically cut and splice the video tape
Digital Video • Digital video is the digitisation of analogue video signals into numerical format • It creates the illusion of full motion by displaying a rapid sequence of changing images on a display device. • Conversion from analogue to digital format requires the use on an ADC (Analogue to Digital Converter) • A Digital to Analogue Converter (DAC) can be used to output digital video on analogue equipment
Digital video editing • Digital video editing can be non-linear process • You can move sections around inside the computer and play those sections back in any order
File Size Considerations Frame rate Number of images displayed within a specified amount of time to convey a sense of motion Usually measured in frames per second Standard video movie 30 fps Movie film 24 fps Video digital at least 15 fps Computer?
File Size Considerations • Frame or Image size • The width and height of each individual frame or image • Determines the quality of the image displayed and the processing involved to display that image • Standard full screen resolution is 640x480 pixels • Video screen display is one fourth the size of the full window screen (320x240)
File Size Considerations • Color depth/Resolution • Number of colors displayed on the screen at one time • Ranging from 1 bit to 8 bit, 16 or 24 bit per pixel
File Size Considerations Quality directly related to frame size and color depth. Quality also depends on content. Motion picture needs higher frame rate File size depends on quality and duration
File Size Considerations File size = Frame Size x Frame Rate x Color Depth x Time • Where: • Frame size = image size ( width x height in pixels) • Frame rate = frames per second • Color depth = measured in bytes • Time = time in seconds This does not include any sound data !
Compression techniques • Since the size of raw digital video is so prohibitively large we need some means to compress the information • Video compression and decompression program, known as Codecs • Lossy compression techniques cause some information to be lost from the original image • Redundant information • Example: Image and video • JPEG and MPEG • Intraframe and Interframe • Lossless compression techniques do not lose information throughout the compression and decompression process • Example use in text images • Exactly same before and after compression • Technique is identify repeating words and assign them a code. • Decompression, the code would be changed back to the actual word.
Standard Broadcast Video • NTSC • North America, South America, Japan • 525 interlaced resolution lines • 30 frames per second (fps) • PAL (Phase Alternate Line) • Australia, South Africa, Europe • 625 interlaced resolution lines • 25 frames per second (fps) • SECAM • France, Russia • 625 interlaced resolution lines • 25 frames per second (fps) • HDTV • Six different formats • Aspect ratio is 16:9
Digital Video File Formats • .MOV signifies Quicktime, an Apple standard. It is playable on Macintosh and Windows machines. • .AVI is a Microsoft standard that is playable on Windows and Macintosh machines. • .MPEG (.MPG) is playable on Unix and Windows machines. Macintoshes can play MPEG, but may have trouble with the audio track. • .RM files are used by RealNetworks streaming. They are playable on Windows, MacOS, and Unix computers. • .ASF files are a Microsoft streaming format, and play on Windows, MacOS, and Solaris. • .WMV files are a Microsoft format used in Microsoft MovieMaker
MPEG video • Named after the Moving Picture Experts Group who devised the compression and file formats • There are a number of MPEG formats: • MPEG-2 is used for digital TV broadcasts and DVDs • MPEG-1 is a format used for low quality video (generally displayed on computers) • MPEG-1 Layer 3 is the popular encoding mechanism for MP3 audio files (more on this later in this course) • MPEG-4 is a new format for multimedia presentations • Can require separate hardware to decode higher quality MPEG video data
A simple scene showing a car moving across a desert landscape Only the difference between the current and next frame needs to be stored This is called interframe coding MPEG compression example
Developed by Apple, Inc. Primarily for playback without any hardware assistance Can achieve compression ratios of 25 to 200:1 The QuickTime format can also store audio, graphics, 3D and text making it more much versatile for multimedia applications QuickTime
Microsoft AVI • Audio Video Interleave format • Interleaving is a technique used to embed two or more things into the same stream of information • In every chunk of information you will find some video data and some audio data 001001010010010101010011110101... 001001010010010101010011110101... ... 001001010010010101010011110101... 8, 16 or 24 bits Video information Audio information 001001010010010101010011110101...
Consumer desktop video • Typified by the Apple iMac DV computer • IEEE 1394 or FireWire interface • Digital camcorders
How Video can be used effectively • Showing physical procedures. Some uses are: • Installing a board in a PC • Adjusting engine timing • Attracting and holding attention. Some uses are: • Advertising products and services • Teaching new skills to busy employees • Presenting scenarios. Some uses are: • Training technicians to respond to equipment malfunctions • Demonstrating possible uses for a product • Analyzing motion . Some uses are: • Body motion to improve athletic performance • Traffic patterns for transportation planning
Advantages and Disadvantages of using video • Carefully planned, well-executed video clips can make a dramatic difference in a multimedia project • Use video only when all other methods (text, still images) are not enough; don’t use it just because it’s possible • Video adds visual impact to multimedia applications: • Advantages • Captures interest • Increase retention • Clarifies complex physical actions and relationships • Can incorporate other media • Disadvantages • Is expensive to produce • Requires extensive memory and storage • Requires special equipment • Does not effectively illustrate abstract concepts and static situations