Multimedia is a term typically used to mean the combination of text, sound, and/or motion video. Multimedia has been described as the addition of animated images, but typically it means one of the following:
Text and sound
Text, sound, and still or animated graphic images
Text, sound, and video images
Video and sound
Multiple display areas, images, or presentations presented concurrently
In live situations, the use of a speaker or actors and "props" together with sound, images, and motion video
The types of computer hardware and software necessary to develop multimedia on the PC vary.
The minimum hardware requirements include:
video accelerator card
sound adapter card with attached speakers.
Key Multimedia Components
A microphone connected to a sound card to input sound.
CD-ROMs and DVD players are used for input and output of multimedia.
A connection to the Internet via a network interface card or a modem. Streaming of audio and video is very popular.
Digital still pictures and video cameras connected to standard computer ports or special card adapters.
A video capture card
MPEG hardware and Web based movie players are used to play movies.
Computer games via DVD or CD require specialized hardware.
The Video Card
A video adapter (also called a display adapter or video board) is an integrated circuit card in a computer that provides digital-to-analog conversion, video RAM, and a video controller so that data can be sent to a computer's display. In a few cases, the video adapter is built in to the monitor. Today, almost all displays and video adapters adhere to the standard Video Graphics Array (VGA).
Standard VGA connector (Female DB-15)
The Video Card
In addition to VGA, most displays adhere to one or more standards set by the Video Electronics Standards Association (VESA).
VESA defines how software can determine the capability of a display.
It identifies resolutions setting beyond those of VGA. These resolutions include 800 X 600, 1024 X 768, 1280 X 1024, and 1600 X 1200 pixels.
Displays use bits to describe color and how many colors can be displayed.
The number of bits used to describe a pixel is called bit-depth
VGA video is 256 colors or 8-bit bit-depth
24-bit bit-depth is known as true color
Dot pitch is the size of an individual beam that gets through to light up a point of phosphor on the screen measured in millimeters with a typical display having a .28 mm dot-pitch
The actual sharpness of a display image is measured in dots-per-inch (dpi). The dots-per-inch is determined by a combination of the screen resolution and the physical screen size.
Display Characteristics Dot pitch is a diagonal distance between the same color phosphor dots. The smaller the dot pitch, the greater the potential image sharpness. The three primary colors used in monitor displays are red, green, and blue (RGB)
On desktop computers, the display screen width relative to height, known as the aspect ratio , is generally standardized at 4 to 3 (usually indicated as "4:3").
Screen sizes are measured in either millimeters or inches diagonally from one corner to the opposite corner. Common desktop screen sizes are 15, 17, and 19-inch. Notebook screen sizes are somewhat smaller.
Two data-compression standards are commonly used with digitized video. These are the Joint Photographic Experts Group (JPEG) and the Moving Picture Experts Group (MPEG) compression standards.
Other Compression Standards
Indeo compression standard, developed by Intel.
Another compression/decompression (codec) standard supported by Video for Windows is Cinepak . This standard uses an AVI file format to produce 40:1 compression ratios and 30-frames per second capture, at 320-by-200 resolution.
JPEG provides enough compression to allow single-frame digitized images to fit on disk drives, but full-motion pictures were going to need much greater compression to be useful on current technology. Therefore, the MPEG format was developed.
MPEG has compression ratios up to 200:1, with high-quality video and audio.
The MPEG standard includes specifications for audio compression and decompression in both MPEG1 and 2.
MPEG1 supports a very near CD-quality stereo output, at data rates between 128kbps and 256kbps.
The MPEG 2 specification supports CD-quality surround-sound (four-channel) output.
Accelerated Graphics Port
Newer Pentium systems were the first to include an advanced Accelerated Graphics Port (AGP) interface for video graphics.
The AGP interface is a variation of the PCI bus design that has been modified to handle the intense data throughput associated with 3 dimensional graphics.
Video Capture Cards
Video capture software is used to capture frames of television video and convert them into digital formats that can be processed by the system.
One of the popular file formats for video is the Microsoft Audio Visual Interface (AVI) format.
Video capture cards are responsible for converting video signals from different sources into digital signals that can be manipulated by the computer.
The video card samples the incoming video signal by feeding it through an A-to-D (analog-to-digital) converter.
Video Card Installation
After the video card has been installed and the monitor has been connected to the video card and plugged into the power outlet, it will be necessary to install the correct drivers for the video card. The Windows 9x operating systems should detect the video card, start the system with basic VGA video drivers, and ask you if you want to install the manufacturer's video drivers.
The Windows 2000 operating system is even more proactive. It will detect the new video card, tell you that it has found the new card, and then automatically load its video drivers. The only time that you should need to be directly involved with the system's video drivers is when PnP fails or the video card is not recognized by the operating system.
Video Memory and Resolution
Monitors are analog, not digital devices. In order for the monitor to work, the digital information in the video memory must be translated into analog form for export to the monitor screen. This is the role of the Random Access Memory Digital-to-Analog Converter (RAMDAC) chip. The RAMDAC chip reads the video memory contents, converts it to analog, and sends it over a cable to the video monitor. The quality of this chip impacts the quality of the image, speed of the refresh rate, and maximum resolution capability. Refresh rate refers to the number of times per second that the video display screen can be redrawn.
Video Memory and Resolution
The video chip set relies on video memory to render the image requested. The basic element of every video image is a dot (or pixel). Many dots comprise what you see displayed on the monitor. Every dot has a location reserved in video memory. The maximum number of dots, which can be displayed, relates to the resolution.
Resolution is expressed as a pair of numbers. Each pair of numbers represents the maximum possible number of dots on a horizontal and vertical axis. The basic VGA resolution is 640 by 480. The higher the resolution, the sharper and clearer the image.
Audio is an integral component of the multimedia experience, but for a PC to have audio capabilities, it requires the use of a sound card.
A sound card is a device that allows the computer to handle audio information.
The basic responsibility of a sound card is the input, processing, and output of audio information
Sound cards produce audio, or synthesize, using three distinct methods:
Frequency Modulation (FM)
Musical Instrument Digital Interface (MIDI)
CDs are 120mm in diameter, 1.2mm thick,
They have the ability to store 650 MB / 70 minutes and 700 MB / 80 minutes of information.
CD-ROM drives can be mounted internally in the computer or as an external drive.
They connect either directly to an external port on the computer (such as USB, FireWire, or parallel) or to a controller installed in one of the computer's expansion slots (usually SCSI).
Common internal connections include IDE and SCSI.
IDE communication cables are 40-pin ribbon cables that connect to the drive and the motherboard.
Currently there are two major types of CD recorders: CD-R and CD-RW.
CD-R – CD-R stands for Compact Disc - Recordable and was the first of the two technologies conceived.
CD-RW – CD-RW stands for Compact Disc - Rewritable.
CD-ROM drive speed rating is based upon multiples of 150 kbps
A CD drive that can write at 3000kb per second is shown as having a 20x (or 20 times 150kb) write speed. A drive listed as 24x/40x has a write speed of 24x and a read speed of 40x.
What is the write speed of this drive in kilobits?
Digital versatile disc (DVD) is a newer technology that builds upon the strengths of CD-ROMs.
DVDs share the same physical size as a CD-ROM, but they can handle a much greater amount of information.
DVDs can store close to 20 times the amount of information as a single CD.
There are four different methods of DVD recording.
DVD-R is similar to CD-R technology in that it allows the media to be written one time only. This method is most often used for DVD authoring and is not very practical for consumers due to the price of drives
DVD-RAM – Using the RAM technology allows users to write and overwrite discs 100,000 times. DVD-RAM uses phase-change technology similar to CD-RW drives and stores 4.7 GB of information on each side of the disc.
The DVD-RW is a technology designed to address compatibility and re-recording issues. Geared more towards general use than authoring
DVD+RW is the latest DVD recording technology. As with DVD-RW, the technology is both compatible with existing hardware and is easily written to multiple times. The major advantage of DVD+RW is the ability to use a variable bit-rate when encoding certain types of media, such as streaming video.
CD Recording Formats (Physical Standards)
CD Recording Formats (Physical Standards)
Red Book – defines the format for audio CDs
Yellow Book – defines the format for data CDs
Green Book – defines the format for interactive CDs
Orange Book – defines the format for recordable CDs
White Book – defines the format for video CDs
Blue Book – defines the format for enhanced CDs
A digital still camera has a series of lenses that focus light to create an image of a scene just like a conventional film camera.
It focuses light onto a semiconductor device that records the light electronically instead of focusing this light onto a piece of film.
It is this electronic information that is broken down into digital data by the computer.
A charge-coupled device (CCD) is the image sensor used by many digital cameras (high-end cameras).
CCDs (Charge Coupled Devices) a solid-state chip containing a series of tiny, light-sensitive photosites
CCD's can be thought of as film for electronic cameras
CCDs are used to capture and store image data in telescopes, scanners, digital still cameras, and digital video cameras.
A good CCD can produce an image in extremely dim light, and its resolution does not degrade in low light the way those of film cameras do.
Complementary metal oxide semiconductor (CMOS) technology is used by some of the more inexpensive cameras.
Resolution is measured in pixels. It is the amount of detail that the camera can capture. Basically, more pixels mean more detail and better quality.
Today, cameras with up to 10.2 million pixels are available, providing the same or even better results than film cameras.
Many digital cameras use an LCD screen, which makes it possible to view and delete pictures right away.
Cameras with fixed storage must be connected to the computer in order to download the images.
This connection can be by a serial, parallel, SCSI, or USB port.
Many newer cameras provide removable storage which allows the images to be transferred to the computer or even directly to a printer without having to connect the camera.
The following list describes storage systems for digital cameras:
Built-in memory – Built-in flash memory is used by many inexpensive cameras
SmartMedia cards –Small Flash memory modules
CompactFlash – Another form of Flash memory, similar to but slightly larger than SmartMedia cards
Memory Stick – This is a proprietary form of Flash memory used by Sony
Floppy disk – Some cameras can store images directly onto an inexpensive floppy disk
Hard disk – Small built-in hard disks, or PCMCIA hard-disk cards, for image storage
Writeable CD and DVD – Writeable CD and DVD drives to store images are used by higher-end cameras
Digital cameras use two main file formats:
JPEG is a compressed format and TIFF is an uncompressed format.
The JPEG file format is used most often for storing pictures, providing different quality settings such as medium or high.
Video cameras or camcorders are similar to a digital camera in that they use CCD.
There are two types of video cameras:
Analog formats include the following:
Standard VHS – Uses the same type of video tapes as a regular VCR.
VHS-C – This is a compact VHS format.
Super VHS – Super VHS tape records an image with a much higher resolution image than standard VHS tape. The video camera itself is a VCR and can be hooked up directly to a television or VCR to copy to standard VHS tapes.
Super VHS-C – A more compact version of Super VHS that uses a smaller size cassette.
8mm – Small 8mm tapes, about the size of an audio cassette, are used and provide about the same resolution as standard VHS.
Hi-8 –Hi-8 camcorders have a higher resolution. Hi-8 tapes are more expensive than ordinary 8mm tapes.
Digital recorders record information digitally, as bytes.
This allows the image to be reproduced without losing any image or audio quality.
Digital video can also be downloaded to a computer, where it can be edited or posted on the Internet.
Digital video has a much better resolution than analog video.