Share this:


MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)

Multimedia is the combination of sound, graphics, animation, and video.
In the world of computers, multimedia is a subset of hypermedia, which combines the elements of multimedia with hypertext so as to link the information.
Overview
In this topic, we discuss issues concerned with using multi-media components. At the end of this section, you will be able to
  • Discuss formats for graphics, sound and video and select the appropriate format for a specific purpose
  • Compare formats for graphics, sound and video
  • Have an appreciation for other technology tools for the display of information
Multimedia is the combination of sound, graphics, animation, and video.
In the world of computers, multimedia is a subset of hypermedia, which combines the elements of multimedia with hypertext so as to link the information.
1. Graphics
There are many formats for storing pictures in digital format. Images associated with personal computer systems are stored in pixel format. A pixel is an individual dot or element with associated intensity and color information. Pixels are combined to form images. The size of each pixel is a function of the quality of the monitor. For most monitors, the pixel size is about 0.28mm.
Color Depth
Some storage formats for pictures involve compression, a technique that reduces the amount of storage space required for the picture, often at the expense of quality. Other formats alter the color depth of the image, as less color will require less storage space. Color depth refers to the number of unique colors used by the image. Using more colors in a picture will require more storage space (bytes). For instance, a single bit can be either on or off. This would correspond to two colors, black and white. Using 8 bits for each pixel would result in a color depth of 256 colors. The more colors you have, the more realistic and natural the image looks. The following table shows the connection between color depth and the number of bits representing that color depth.
Color Depth
(in pixels)
Number of Bits
Image
Image Size
(in bytes)
Download Time
(at 28.8Kbps)
2
1
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
1998
0.55
16
4
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
4666
1.29
256
8
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
10113
2.80
65536
16
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
22494
6.24
16.7 million
24

Increasing the size of the image introduces distortion, as the graphics package must calculate what the new pixels should look like. The image on the right shows a portion of what this increased image size looks like, with the resultant distortion clearly visible.
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
Graphic Format
File Extension
Color Depth
Description
Bitmap
.bmp
All
Microsoft Windows format. Supported by all Microsoft operating systems. Not used for web pages.
GIF
.gif
8 bit
Graphics Interchange Format. Used for web pages.
JPEG
.jpg

24/16 bit
Joint Pictures Entertainment Group. Used for web pages.
TARGA
.tga
All
Used primarily for image creation, composing and editing.
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
Best Quality
20% compression
22494 bytes
Medium Quality
70% compression
33
40 bytes
Low Quality
90% compression
1988 bytes
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)

Blur
Cutout
Vortex
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
This is a screen capture of the Microsoft GIF animator program. The program is currently supplied with Microsoft Frontpage (as of December 1998). It is simple to use and creates effective animations.
Sound Quality
Sample rate
Description
Telephone
11,025
Suitable for speech
Radio
22,050
Suitable for music
CD
44,100
Suitable for high quality music
Stereo files are twice the size in bytes as a mono file due to each sample containing left and right channel information. They have the advantage of appearing to give distance separation and are useful to create special effects. This must be traded against the available bandwidth and how long the file takes to download. Mono files are the most common format. The following table shows the comparative file sizes (approximate) for one second of recorded speech.
Sample Rate
8 bit
Mono
8 bit
Stereo
16 bit
Mono
16 bit
Stereo
11KHz
11KB
22KB
22KB
44KB
22KHz
22KB

44KB
44KB
88KB
44KHz
44KB
88KB
88KB
166KB
Compression(Codecs)
A codec is a “compression decompression” device. It is often implemented in software, though many new accelerated cards have codecs implemented in hardware for faster coding and decoding of signals. A codec is used to alter the signal in order to reduce the bandwidth requirements (i.e., the size of the file is compressed making it smaller and thus quicker to transfer or download). The codec converts the file format to a format suitable for playing on the destination hardware.
The following is a brief discussion on two popular speech codecs
  • ADPCM (Adaptive Differential Pulse Code Modulation)
    This codec reduces the file size by over 50%. However, any compression causes loss of sound quality. There is no generally accepted standard for ADPCM, with codecs generally provided by manufacturers of sound cards that are installed using a software install program.
  • PCM (Pulse Code Modulation)
    Another common codec supported by all Windows operating systems.
Streaming Audio
The major problem associated with the previous format of waveform audio is the file size. When you use a waveform audio file on a web page, the browser must download the entire file before it can be played. For files of reasonable size, this leads to long delays for the receiver. Streaming audio addresses the issue of this delay by allowing the file to be played whilst it is still being downloaded. Special players are required for viewing and playing streaming audio clips.
Streaming audio is primarily associated with Real Networks. “Real Player” supports the playing of streaming audio over the Internet. The advantages of using streaming audio are
  • the use of a special codec that reduces the bandwidth requirements for audio down to about 5Kbps
  • instant playing of the audio clip
  • suits limited bandwidth connections (i.e., a dial-up user with a 28.8Kbps modem)
When a user selects a streaming audio clip, the streaming audio player contacts the server and establishes the bandwidth and delays between the user computer and the host server. A few seconds of the clip is then downloaded into temporary buffer storage before the clip begins to play. As the clip begins to play, more content is downloaded and placed into temporary storage. If there is a congestion delay in the Internet connection, the clip continues to play using the contents of the buffer storage. Hopefully, before the buffer storage is exhausted, the congestion delay will cease and thus the buffer storage will fill up again. In this manner, the streaming player tries to achieve smooth playback of the clip. Without using storage, gaps or breaks in the audio would be evident when a congestion delay occurred.
A special content provider program is necessary for producing streaming audio clips. A limited free version can be downloaded from the Real Networks web site. In addition, to provide streaming audio clips from a server requires the use of a streaming server.
Sample audio file
(8KHz, 8 bit mono WAV file, 12.4KB, 1.55 seconds duration)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
Converted sound file from the WAV file above.
(Streaming audio format, 4.45KB, 1.55 seconds duration)
Recording and editing of sound files
To record WAV sound files you need a microphone (or sound source such a tape recorder), sound card, and sound recorder program.
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)

The Windows operating system provides the program “Sound Recorder”. This program is simple to use and can create short WAV files. The sample rate is adjustable and it can record in mono or stereo. Simplistic editing of the sound file (delete before cursor, delete after cursor) is provided.
For more sophisticated sound recording and editing, a program such as “Cool Edit for Windows” is necessary. This program has many more features and is a good tool for producing quality sound WAV files.
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
To create streaming audio files, you need a program such as “Real Encoder” from Real Networks. This takes an existing sound WAV file or a live sound source and converts it to a streaming audio file. It is possible to specify a number of parameters such as Internet bandwidth when creating the file.
Other considerations
As always, bandwidth is a premium for the Internet. This means that you must tradeoff quality and size for quick download speed and fast display. New technology like streaming audio can deliver more content utilizing the same or less bandwidth.
However, streaming audio content is not currently supported (as at Dec 1998) within a web browser. This means using streaming audio poses the problem of requiring the receiver to have the streaming player installed on their computer. For this reason alone, you should ensure that an Internet link to where the player can be downloaded from is available on the web page.
In addition, using a separate player rather than the browser (which supports WAV format) means greater memory requirements. This is because the player needs to be started and loaded into memory, in addition to the web browser.
This also raises a contextual issue, as the user is now interfacing with two packages, the browser and the player. This can lead to confusion and reduce the effectiveness of the presentation or learning experience.
If producing for a CD-ROM, many of the issues related to sound file sizes and sampling rates do not apply to the same extent. A CD-ROM can provide information at a much faster rate than a dial-up modem. Typically, a 2X CD-ROM can transfer data at 300KB per second. This means higher quality sound can be used due to the larger available bandwidth.
4. Videos
Video Recording is the process of recording still or moving images electronically, rather than photochemical as in photographic film.

The delivery of video on web pages has tilled recently been fraught with difficulty. Lack of standards and support a few years ago were major issues. The reality of the Internet and lack of available bandwidth means that delivery of video content is severely restricted to simple slow moving content (such as people speaking face to face or teachers delivering lectures) and in very small frame windows (of 320×240 or less). The frame rate (the number of images displayed per second) has also been a problem, with a lot of real-time video (such as net meeting or video conferencing software) achieving rates of 10 frames per second (fps) or less. Around 15fps is the minimum frame rate required for smooth movement. Television frame rates are 30fps for NTSC (American standard) and 25fps for PAL (Europe, NZ standard).
The more frames per second the more realistic movement appears. However, this requires greater bandwidth. With video we are stretching the limits considerably. The features of video are
  • content keeps changing so we need a reasonable frame rate else the motion appears jerky
  • the window size needs to be a reasonable size to ensure enough detail is perceived
  • sound is added for maximum effect
Every increase in a video parameter means you require more bandwidth. For instance, more frames per second require more bandwidth. Larger window sizes require more bandwidth. A video with audio needs more bandwidth than a video that has no audio.
Just what are the bandwidth requirements of a video image? Well, that depends on the size of image, the color depth, the frame rate and a number of other factors. Consider a 15fps video using 256 color (8-bit color depth) of 320×240 in size, lasting 10 seconds in duration. The bandwidth per second required for this is
15 * ((320 * 240) * 8) = 9.216Mbps
This does not even include audio yet. As you can see, this video cannot be played over the Internet using a dial-up 28.8Kbps connection. In fact, it would not even play on some personal computers. What is needed is a mechanism of reducing the information in the video to a much smaller size (i.e., reduce the bandwidth required). This is achieved by eliminating redundant information from the video, and compressing what’s left. This is called compression. The device (either in software or hardware) that does compression of the video and decompresses it ready for playing is called a codec.
Frame Sizes and Formats
There is a number of common video formats for personal computers. The three most common formats available today are
  • MOV (Developed and supported by Apple Inc.)
  • AVI (Developed and supported by Microsoft.)
  • MPEG
Video has standardized on a 4:3 ratio. This ratio is an accepted standard. Typical video sizes are
  • 320 x 240
  • 160 x 120
When producing video for multi-media productions such as CD-ROM and the Internet, you should adhere to common standards. This means using commonly accepted frame sizes, frame rates, color depths, compression codecs and video formats. Using a non-standard format may cause problems in playback on the client computer, such as the inability to play the video.
Codec
Codec isthe hardware that can convert audio or video signals between analog and digital forms.
Codec compresses and decompresses the video stream. When a codec is applied, it looks at the original video stream and changes it, saving the result to a file. When the file is played back, the codec interprets the changes and attempts to reconstruct the original video stream.
A lossless compression scheme preserves the original data, so that the resultant video after decompression looks the same as that before it was compressed. Most lossless compression schemes use run length encoding (RLE). This works well with computer generated images, but is not very effective when applied to digitized video. The reason for this is because RLE works by discarding continuous regions that have the same colors. Computer generated images tend to have more solid colors than digitized video, so RLE is more effective for these.
A lossy compression scheme removes data from the video stream that the viewer is unlikely to notice. The amount of information that is lost depends on how much compression is applied.
A spatial compression scheme compresses the information in every frame. This can result in blurring, blockiness (small blocks of the same color) and streaking (lines of the same color).
A temporal compression scheme compresses the data by comparing frames over time. Frame differencing is a type of temporal compression that stores data for only the frames that contain changes. This can result in blockiness.
The following is a summary of the more common video codecs supported by personal computers (as at Dec 1998).
Video Codec
Description

RLE
Run length encoding is a technique that discards continuous regions that have the same color. It is suitable for 8-bit (256) color video.
Indeo
Use this codec to compress 24-bit color for playback from CD-ROM, or for the original digital video capture.
Cinepak
Use this codec to compress 24-bit video for playback from CD-ROM. The codec is much faster at decompressing that compressing so is good for playback of moving video content.
Microsoft Video 1
This codec is a lossy, spatial compressor. It supports 8-bit and 16-bit color.
Key frames
A key frame contains the entire image information and is used as a reference for subsequent frames in a sequence. In the illustration below, key frames are repeated every seven frames. Intermediate frames that occur between key frames only contain the changes between that frame and the key frame. This method reduces the file size of the video.
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
The intermediate frames are called delta frames.
AVI (Audio Video Interleave)
AVI is a format Microsoft introduced with the Windows 3.1 operating system. It intermixes both audio and video content within the file. The video and audio streams in the file are stored sequentially, without time stamps. A header in the file indicates the rate at which the video and audio streams are to be played. The audio stream is stored as a WAV file.
When a user selects a streaming video clip, the streaming video player contacts the server and establishes the bandwidth and delays between the user computer and the host server. A few seconds of the clip is then downloaded into temporary buffer storage before the clip begins to play. As the clip begins to play, more content is downloaded and placed into temporary storage. If there is a congestion delay in the Internet connection, the clip continues to play using the contents of the buffer storage. Hopefully, before the buffer storage is exhausted, the congestion delay will cease and thus the buffer storage will fill up again. In this manner, the streaming player tries to achieve smooth playback of the clip. Without using storage, gaps or breaks in the video would be evident when a congestion delay occurred.
Any number of video streams and audio channels can be combined with transition effects (how one video stream is changed to a different video stream) into a single video. It supports a wide variety of frame formats, frame sizes and codecs. It is ideal for producing video content for CD-ROM.
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
Often, AVI files can be further reduced in file size by conversion to MPEG format. The XING encoder is relatively inexpensive and should be considered as an option for any serious multi-media developer. This package cannot be used to create AVI or MPEG content. It can only convert existing AVI files to MPEG format.
It is a free download from Real Networks. A player is required to play the generated video stream. In addition, a streaming server is recommended to handle the delivery of streaming video content over the Internet. It is possible to place limits on the data rate of the video content when it is created.
This product can also produce live streaming video content and slide shows (graphics plus optional audio).
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
Video Type
File Size
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flybyc.avi
493KB
Cinepak codec
CD-ROM only
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flybym.avi
491KB
Microsoft Video 1
CD-ROM only
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flybyi.avi
1287KB
Intel Indeo(R) Video 3.2
CD-ROM only
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flyby.mpg
747KB
Converted with XingMPEG encoder
CD-ROM only
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flyby1.rm
25KB
Data rate set to 28.8Kbps, smoothest motion

EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flyby2.rm
13KB
Data rate set to 28.8Kbps, sharpest image
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flyby3.rm
31KB
Data rate set to 56Kbps, smoothest motion
CD-ROM only
EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)
flyby4.rm
24KB
Data rate set to 56Kbps, sharpest image

CD-ROM only


EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)

subscriber

1 Comment

  • EcoleBooks | COMPUTER O LEVEL(FORM FOUR) NOTES - MULT-MEDIA (GRAPHICS,ANIMATIONS,SOUNDS AND VIDEOS)

    minö kid, September 17, 2023 @ 5:09 am Reply

    I want notes

Leave a Reply

Your email address will not be published. Required fields are marked *

Accept Our Privacy Terms.*