Page 230 - DCAP303_MULTIMEDIA_SYSTEMS

Multimedia Systems

notes Comparison MiDi Digitized audio
Analogy Vector Graphics Bitmap Image
Ease to incorporate Must have knowledge Does not require much knowledge

13.7 animation, video and Digital Movie tools

Animation and digital movies are sequences of bitmapped graphic scenes (frames, rapidly played
back. Most authoring tools adapt either a frame or object oriented approach to animation.
Moviemaking tools typically take advantage of QuickTime for Macintosh and Microsoft Video
for Windows and lets the content developer to create, edit and present digitized motion video
segments.
13.7.1 video formats
A video format describes how one device sends video pictures to another device, such as the
way that a DVD player sends pictures to a television or a computer to a monitor. More formally,
the video format describes the sequence and structure of frames that create the moving video
image.

Video formats are commonly known in the domain of commercial broadcast and consumer devices;
most notably to date, these are the analog video formats of NTSC, PAL, and SECAM. However,
video formats also describe the digital equivalents of the commercial formats, the aging custom
military uses of analog video (such as RS-170 and RS-343), the increasingly important video formats
used with computers and even such offbeat formats such as color field sequential.

Video formats were originally designed for display devices such as CRTs.
Since other kinds of displays have common source material and video formats enjoy wide adoption
and have convenient organization, video formats are a common means to describe the structure
of displayed visual information for a variety of graphical output devices.

13.7.2 Common organization of video formats
A video format describes a rectangular image carried within an envelope containing information
about the image. Although video formats vary greatly in organization, there is a common
taxonomy:

• A frame can consist of two or more fields, sent sequentially, that are displayed over time
to form a complete frame. This kind of assembly is known as interlace. An interlaced video
frame is distinguished from a progressive scan frame, where the entire frame is sent as a
single intact entity.
• A frame consists of a series of lines, known as scan lines. Scan lines have a regular and
consistent length in order to produce a rectangular image. This is because in analog formats,
a line lasts for a given period of time; in digital formats, the line consists of a given number
of pixels. When a device sends a frame, the video format specifies that devices send each
line independently from any others and that all lines are sent in top-to-bottom order.
• As above, a frame may be split into fields – odd and even (by line “numbers”) or upper and
lower, respectively. In NTSC, the lower field comes first, then the upper field, and that is
the whole frame. The basics of a format are Aspect Ratio, Frame Rate, and Interlacing with
field order if applicable: Video formats use a sequence of frames in a specified order. In
some formats, a single frame is independent of any other (such as those used in computer

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