9.4.4 Multimedia Systems
http://multimediasystems.wikispaces.com/Examples+Of+Multimedia+Systems
Glossary
Term Definition
Multimedia Systems An information system that combines different types of digital
media to produce a product to achieve a purpose, such as to
educate, train, entertain or simply to enhance the provision of
information.
Text Data type consisting of letters, numbers and other characters.
Audio Sound that has been digitised
Frequency The number of times per second that a complete wavelength
occurs.
Amplitude Determines the volume or level of the sound.
Images Data in the form of pictures, such as a drawing, painting or
photograph
Pixel The smallest part of the screen that can be controlled by the
computer
Resolution A measurement of the detail of an image produced on a screen
Cel-based Animation Sequence of cels (images) with small changes between each cel.
When played the illusion of movement is created.
Path-based animation A line (path) is drawn for each character to follow. When played
each character moves along their line in front of the
background.
Animation The movement of graphics, as in a cartoon
Video Data type that combines pictures and sound displayed over time
Codec Short for compression and decompression
Hyperlinks •A link that transports the user to other parts of the system;
, allowing them to freely explore areas of interest. In a
multimedia system, the link may transport them to a variety of
different media types including image, sound, video or
animation.
Hypermedia A combination of media whose locations are linked to provide a
easy way to navigate between the documents
Frame A single image in a film
Storyboard A series of frames, each representing a different action or
screen image
Linear A sequential path that is set up quickly
Hierarchical A sequential path in a top down design
Interactivity The degree of control the participant has over the system
Characteristics of Multimedia Systems
Multimedia Systems
- Combines different types of media into interactive information systems
- The creation of multimedia systems can involve all information processes (COASPTD), but
focuses primarily on the information process of displaying
- The integration of various media into a single presentation is a defining feature of multimedia
- Interactive nature of most multimedia allows users to explore the content in any order and at
their own pace
- Most combine text, images and animation and many also include audio and video
- Professional developed multimedia systems require a broad range of expertise
- Examples: flight simulators are used to train pilots and computer games are a popular form of
escape for many; schools and universities use a variety of multimedia systems to enhance the
learning experiences of students
- Widespread use due to increasing speed of processing and communication technologies, and
advances in compression and decompression techniques, resulting in higher quality content
using smaller file sizes over faster communication links
Text and Numbers
- Most multimedia systems represent the bulk of their information as text and use images, sound,
video and other media to reinforce it
- Some multimedia systems limit text for user instructions e.g. in games
, - Two main commonly used methods for digitally representing text are systems based on ASCII
and EBCDIC
- Quantities that can be expressed on a numerical scale are represented using numbers. Unlike
other types of media, numbers have magnitude. Number media type is used to represent:
o Integers (whole numbers)
o Real numbers (decimals)
o Currency
o Boolean (true/false) - represented using a single bit, usually true is 1 and false is 0
o Dates and time
- Numbers are less commonly used except for the underlying code that controls the presentation.
However when they are displayed on screen, it is usually represented by text rather than
numerical values
- In Multimedia systems, both text and numbers are displayed as images using fonts. Fonts
describe how each character will be rendered when displayed
- There are two main types of fonts: outline and raster
o Outline fonts describe characters using mathematical descriptions of the lines and
curves within each character
o Raster fonts store a bitmap of each character
- Outline fonts are able to be enlarged without becoming jagged and pixelated, therefore they
should be used wherever possible, especially when printing
-
- It is critical to ensure that fonts used within a multimedia presentation will be available on the
end-user’s machine. If the end-user’s operating system does not have that font installed, a
different font may be automatically substituted and may affect the readability of the display
- Some presentation and multimedia software include the ability to embed the font within the
presentation. If this function is not available, then font selection should be restricted to those
included within target systems
Audio
- Represents sounds, including music, speech, sound effects
- All sounds are transmitted through the air as compression waves: vibrations cause the
molecules in the air to compress and then decompress, and this compression is passed onto
further molecules and so the wave travels through the air
- Sound waves are the data, what we recognise as sound is the information
- File formats for storing audio include MP3, WAV and WMA for samples sounds, and MID which
represents individual notes much like a music score
- All waves have 2 components:
, o Frequency, measured in hertz (Hz): the number of times per second that a complete
wavelength occurs. It determines the pitch that we hear: higher frequencies is higher
pitched sounds. Human ear can hear frequencies in the range 20 to 20,000Hz
o Amplitude, measured in decibels (db): determines the volume or level of sound. Very
low amplitude waves cannot be heard, whereas very high amplitude waves can damage
hearing. 0 decibels is the threshold of hearing, sounds above 120 decibels can hurt
- Audio data can be represented in binary using two methods:
o Sampled Audio: The level of the signal is recorded at precise intervals of time which
results in a large number of points that can be joined to approximate the shape of the
original sound wave. Used when a real sound wave is converted into digital as opposed
to computer generated sound. Accuracy and quality of audio samples depend on the
number of samples per second and the number of bits used to represent each of these
samples. E.g. stereo music contains 44100 samples for each second of audio for two
channels and each of these samples is 16 bits long, which means 300 second long audio
requires storage of 44100 samples x 300 secs x 16 bits x 2 channels = about 50MB of
storage. Sample rate can also be expressed in hertz, e.g. 44100 samples = 44100 Hz or
44.1kHz. Today it is common for sound data to be recorded using 6 channels (surround
sound), so various compression techniques have been devised to reduce the size of
samples sound data, however greater processing power is required to decompress prior
to playback.
o Individual Notes: describes the sound in terms of the properties of each individual note,
generally used for computer generated sound, particularly musical compositions. This
music representation is similar to a traditional music score, where the vertical position
on a music score determines pitch and the symbol determines duration. In binary, each
note in the music is represented in terms of its pitch (frequency) and its duration (time).
The most common storage format for such files is the MIDI (Musical Instruments Digital
Interface) format. Files that specify the tonal qualities of an instrument or contain real
recordings are used in conjunction with the notes to electronically reproduce the music.
- Example of compression technique: MP3 uses a lossy compression technique, meaning some
detail of original sound is lost. It removes parts of the sound that are frequencies outside the
range of normal human hearing.
Images and/or Animations
- Used to represent data that’ll be displayed as visual information. All information displayed on
monitors and printed as hardcopy is ultimately represented as images.
- Screens and printers used to display image media - however text and numbers are organised
into image data only in preparation for display.
- The method of representing the image is chosen to best suit the types of processing required.
E.g. the representation used when editing a photo to be included in a commercial publication
differs to that used when drawing border around some text in word processor.
- Two different techniques for representing images: bitmap (JPEG, GIF, PNG)/vector (SVG, WMF,
EMF)
Bitmap
, - Represents each element/dot in picture separately. These dots/pixels can each be a different
colour and each colour is represented as a binary number.
- Total number of colours present in an image has a large impact on the overall size of binary
representation, e.g. black and white image only requires 1 bit for each pixel (1 = black, 0 =
white). For 256 colours, 8 bits are required for each pixel so image would require 8 x as much
storage of a similar black and white image.
- Number of bits/pixel is often referred to as image’s colour/bit depth. The higher the bit depth,
the more colours it includes and therefore the larger storage requirements for image will be.
- Resolution determines how clear/detailed image appears - it is usually expressed in terms of
pixel width by pixel height.
- To calculate the uncompressed storage requirements for a bitmap:
1. Calculate total number of pixels
2. Multiply by colour/bit depth
- E.g. if image has resolution of 800 x 600 pixels then the total number of pixels is 480,00.
If bit depth is 24 bits then each pixel requires 3 bytes storage - therefore total file size in bytes
will be 480,000 x 3 bytes/pixel → 1,440,000 bytes
To convert this figure to kB divide by 1024. 1,440,000 divided by 1024 = 1406kB.
To convert this figure to MB divide by 1024. 1406 divided by 1024 = 1.37MB.
- When using bitmap images within multimedia projects it is vital to consider the likely resolution
of end users’ display device to determine most suitable resolution for bitmap.
- Typically screens have resolutions ranging from 800 x 600 pixels up to 1920 x 1200 pixels or
greater.
- Bitmap images are often compressed to reduce their size prior to storage/transmission.
Vector
- Represent each portion of image mathematically (like outline fonts). Stored data used to
generate the image is a mathematical description of each each shape the makes up the final
image.
- Each shape within a vector image is a separate object that can be altered without affecting
other objects. E.g. a single line within a vector image can be selected and its size/colour/position
altered independently from rest of the image.
- Total size of data required to represent a vector image is less than that for an equivalent bitmap
image; however processing needed to transform data into a visual image is far greater.
- Vector images can be resized to any required resolution without loss of clarity and without
increasing size of data used to represent image. Vector graphics generally unsuitable for
representing photographic images - detail required is difficult and inefficient to reproduce
mathematically.
- Animations are often produced using a combination of cel-based and path-based approaches.
- Cel-based involves creating a sequence of individual cels where each cel is slightly different to
the previous one (e.g. pivot stick animation). Cel-based techniques can be used to create the
entire animation as a sequence of complete images/can be used to create small animations of
individual characters
http://multimediasystems.wikispaces.com/Examples+Of+Multimedia+Systems
Glossary
Term Definition
Multimedia Systems An information system that combines different types of digital
media to produce a product to achieve a purpose, such as to
educate, train, entertain or simply to enhance the provision of
information.
Text Data type consisting of letters, numbers and other characters.
Audio Sound that has been digitised
Frequency The number of times per second that a complete wavelength
occurs.
Amplitude Determines the volume or level of the sound.
Images Data in the form of pictures, such as a drawing, painting or
photograph
Pixel The smallest part of the screen that can be controlled by the
computer
Resolution A measurement of the detail of an image produced on a screen
Cel-based Animation Sequence of cels (images) with small changes between each cel.
When played the illusion of movement is created.
Path-based animation A line (path) is drawn for each character to follow. When played
each character moves along their line in front of the
background.
Animation The movement of graphics, as in a cartoon
Video Data type that combines pictures and sound displayed over time
Codec Short for compression and decompression
Hyperlinks •A link that transports the user to other parts of the system;
, allowing them to freely explore areas of interest. In a
multimedia system, the link may transport them to a variety of
different media types including image, sound, video or
animation.
Hypermedia A combination of media whose locations are linked to provide a
easy way to navigate between the documents
Frame A single image in a film
Storyboard A series of frames, each representing a different action or
screen image
Linear A sequential path that is set up quickly
Hierarchical A sequential path in a top down design
Interactivity The degree of control the participant has over the system
Characteristics of Multimedia Systems
Multimedia Systems
- Combines different types of media into interactive information systems
- The creation of multimedia systems can involve all information processes (COASPTD), but
focuses primarily on the information process of displaying
- The integration of various media into a single presentation is a defining feature of multimedia
- Interactive nature of most multimedia allows users to explore the content in any order and at
their own pace
- Most combine text, images and animation and many also include audio and video
- Professional developed multimedia systems require a broad range of expertise
- Examples: flight simulators are used to train pilots and computer games are a popular form of
escape for many; schools and universities use a variety of multimedia systems to enhance the
learning experiences of students
- Widespread use due to increasing speed of processing and communication technologies, and
advances in compression and decompression techniques, resulting in higher quality content
using smaller file sizes over faster communication links
Text and Numbers
- Most multimedia systems represent the bulk of their information as text and use images, sound,
video and other media to reinforce it
- Some multimedia systems limit text for user instructions e.g. in games
, - Two main commonly used methods for digitally representing text are systems based on ASCII
and EBCDIC
- Quantities that can be expressed on a numerical scale are represented using numbers. Unlike
other types of media, numbers have magnitude. Number media type is used to represent:
o Integers (whole numbers)
o Real numbers (decimals)
o Currency
o Boolean (true/false) - represented using a single bit, usually true is 1 and false is 0
o Dates and time
- Numbers are less commonly used except for the underlying code that controls the presentation.
However when they are displayed on screen, it is usually represented by text rather than
numerical values
- In Multimedia systems, both text and numbers are displayed as images using fonts. Fonts
describe how each character will be rendered when displayed
- There are two main types of fonts: outline and raster
o Outline fonts describe characters using mathematical descriptions of the lines and
curves within each character
o Raster fonts store a bitmap of each character
- Outline fonts are able to be enlarged without becoming jagged and pixelated, therefore they
should be used wherever possible, especially when printing
-
- It is critical to ensure that fonts used within a multimedia presentation will be available on the
end-user’s machine. If the end-user’s operating system does not have that font installed, a
different font may be automatically substituted and may affect the readability of the display
- Some presentation and multimedia software include the ability to embed the font within the
presentation. If this function is not available, then font selection should be restricted to those
included within target systems
Audio
- Represents sounds, including music, speech, sound effects
- All sounds are transmitted through the air as compression waves: vibrations cause the
molecules in the air to compress and then decompress, and this compression is passed onto
further molecules and so the wave travels through the air
- Sound waves are the data, what we recognise as sound is the information
- File formats for storing audio include MP3, WAV and WMA for samples sounds, and MID which
represents individual notes much like a music score
- All waves have 2 components:
, o Frequency, measured in hertz (Hz): the number of times per second that a complete
wavelength occurs. It determines the pitch that we hear: higher frequencies is higher
pitched sounds. Human ear can hear frequencies in the range 20 to 20,000Hz
o Amplitude, measured in decibels (db): determines the volume or level of sound. Very
low amplitude waves cannot be heard, whereas very high amplitude waves can damage
hearing. 0 decibels is the threshold of hearing, sounds above 120 decibels can hurt
- Audio data can be represented in binary using two methods:
o Sampled Audio: The level of the signal is recorded at precise intervals of time which
results in a large number of points that can be joined to approximate the shape of the
original sound wave. Used when a real sound wave is converted into digital as opposed
to computer generated sound. Accuracy and quality of audio samples depend on the
number of samples per second and the number of bits used to represent each of these
samples. E.g. stereo music contains 44100 samples for each second of audio for two
channels and each of these samples is 16 bits long, which means 300 second long audio
requires storage of 44100 samples x 300 secs x 16 bits x 2 channels = about 50MB of
storage. Sample rate can also be expressed in hertz, e.g. 44100 samples = 44100 Hz or
44.1kHz. Today it is common for sound data to be recorded using 6 channels (surround
sound), so various compression techniques have been devised to reduce the size of
samples sound data, however greater processing power is required to decompress prior
to playback.
o Individual Notes: describes the sound in terms of the properties of each individual note,
generally used for computer generated sound, particularly musical compositions. This
music representation is similar to a traditional music score, where the vertical position
on a music score determines pitch and the symbol determines duration. In binary, each
note in the music is represented in terms of its pitch (frequency) and its duration (time).
The most common storage format for such files is the MIDI (Musical Instruments Digital
Interface) format. Files that specify the tonal qualities of an instrument or contain real
recordings are used in conjunction with the notes to electronically reproduce the music.
- Example of compression technique: MP3 uses a lossy compression technique, meaning some
detail of original sound is lost. It removes parts of the sound that are frequencies outside the
range of normal human hearing.
Images and/or Animations
- Used to represent data that’ll be displayed as visual information. All information displayed on
monitors and printed as hardcopy is ultimately represented as images.
- Screens and printers used to display image media - however text and numbers are organised
into image data only in preparation for display.
- The method of representing the image is chosen to best suit the types of processing required.
E.g. the representation used when editing a photo to be included in a commercial publication
differs to that used when drawing border around some text in word processor.
- Two different techniques for representing images: bitmap (JPEG, GIF, PNG)/vector (SVG, WMF,
EMF)
Bitmap
, - Represents each element/dot in picture separately. These dots/pixels can each be a different
colour and each colour is represented as a binary number.
- Total number of colours present in an image has a large impact on the overall size of binary
representation, e.g. black and white image only requires 1 bit for each pixel (1 = black, 0 =
white). For 256 colours, 8 bits are required for each pixel so image would require 8 x as much
storage of a similar black and white image.
- Number of bits/pixel is often referred to as image’s colour/bit depth. The higher the bit depth,
the more colours it includes and therefore the larger storage requirements for image will be.
- Resolution determines how clear/detailed image appears - it is usually expressed in terms of
pixel width by pixel height.
- To calculate the uncompressed storage requirements for a bitmap:
1. Calculate total number of pixels
2. Multiply by colour/bit depth
- E.g. if image has resolution of 800 x 600 pixels then the total number of pixels is 480,00.
If bit depth is 24 bits then each pixel requires 3 bytes storage - therefore total file size in bytes
will be 480,000 x 3 bytes/pixel → 1,440,000 bytes
To convert this figure to kB divide by 1024. 1,440,000 divided by 1024 = 1406kB.
To convert this figure to MB divide by 1024. 1406 divided by 1024 = 1.37MB.
- When using bitmap images within multimedia projects it is vital to consider the likely resolution
of end users’ display device to determine most suitable resolution for bitmap.
- Typically screens have resolutions ranging from 800 x 600 pixels up to 1920 x 1200 pixels or
greater.
- Bitmap images are often compressed to reduce their size prior to storage/transmission.
Vector
- Represent each portion of image mathematically (like outline fonts). Stored data used to
generate the image is a mathematical description of each each shape the makes up the final
image.
- Each shape within a vector image is a separate object that can be altered without affecting
other objects. E.g. a single line within a vector image can be selected and its size/colour/position
altered independently from rest of the image.
- Total size of data required to represent a vector image is less than that for an equivalent bitmap
image; however processing needed to transform data into a visual image is far greater.
- Vector images can be resized to any required resolution without loss of clarity and without
increasing size of data used to represent image. Vector graphics generally unsuitable for
representing photographic images - detail required is difficult and inefficient to reproduce
mathematically.
- Animations are often produced using a combination of cel-based and path-based approaches.
- Cel-based involves creating a sequence of individual cels where each cel is slightly different to
the previous one (e.g. pivot stick animation). Cel-based techniques can be used to create the
entire animation as a sequence of complete images/can be used to create small animations of
individual characters
