multimedia element \ video

1. By: Taj Elsir Hassan Suliman
Computer Department
2013
Multimedia
Fundamental concepts in video

2. Video Concept
 Video is an excellent tool for delivering multimedia.
 Video places the highest performance demand on computer and its
memory and storage.
 Digital video has replaced analog video as the method of choice for
making and delivering video for multimedia.

3. Video Concept
 Digital video device produces excellent finished products at a
fraction of the cost of analog.
 Digital video eliminates the image-degrading analog-to-digital
conversion.
 Many digital video sources exist, but getting the rights can be
difficult, time-consuming, and expensive.

4. 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.

5. Analogue Video
 Composite analogue video has all the video components:
 brightness, colour and synchronization
 Then combined into one signal for delivery
 Example : traditional television
 Problems: colour blending, low clarity, high generation lost, difficult
to edit.
DIGITAL ANALOGUE

6. Digitizing Video
 Digital video combines features of graphics and audio to create
dynamic content for multimedia products.
 Video is simply moving pictures.
 Digitized video can be edited more easily.
 Digitized video files can be extremely large.

7. Digitizing Video
 Digital video is often used to capture content from movies and television to be used
in multimedia.
 A video source (video camera ,VCR, TV or videodisc) is connected to a video capture
card in a computer.
 As the video source is played, the analog signal is sent to the video card and
converted into a digital file (including sound from the video).
VCR
Video Overlay Board /
Video Capture Card
PC

8. Analogue signal from VCR
Converted to DIGITAL
by VIDEO CAPTURE CARD
The converted
signal is
entered inside a
computer
Signal is processed
Video is edited
using video editing
software software

9. 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

10. Digital Video
 Video clip stored on any mass-storage device can be played back on a computer’s
monitor without special hardware.
 Setting up a production environment for making digital video, requires some
hardware specifications.
 Some specifications include computer with FireWire connection and cables, fast
processor, plenty of RAM, fast and big hard disk.

11. File Size and Formats
 There is an important consideration:
 file size in digitized video which included
1. frame rate
2. image size
3. color depth.
File Size (bytes)= Frame Size(bytes) x Frame
Rate (fps) x Video Time(sec)

12. File Size and Formats1. Frame Rate
 animation is an illusion caused by the rapid display of still
images.
 television and movies play at 30 fps but acceptable playback
can be achieved with 15 fps.

13. File Size and Formats2. Image Size
 A standard full screen resolution is 640x480 pixels but to safe storing
space a video with 320x240 for a computer display is still acceptable.
 New high-definition televisions (HDTV) are capable of resolutions up
to 1920×1080p60,
 1920 pixels per scan line by 1080 scan lines, progressive, at 60
frames per second.

14. File Size and Formats
3. Color Depth
 The quality of video is dependent on the color quality (related to the
number of colors) for each bitmap in the frame sequence.

15. 3. Color Depth
 The color depth below 256 colors is poorer-quality image.
 The frame rate to below 15 fps causes a noticeable and distracting
jerkiness that unacceptable.
 Changing the image size and compressing the file therefore become
primary ways of reducing file size.
File Size and Formats
24 bit 8 bit (256 colors)16 bit

16. A video clip is captured with a resolution of
320 x 240, and using a color depth of 16
bits, the frame rate is 25 fps , and the clip has
a duration of 29 seconds, calculate the file
size of the video clip?
Solutions:
Give : depth=16 bit (2 bytes), t=29 sec, frame
rate = 25 fps
Example:

17. Frame Size = Total no of pixels x Depth
= 320 x 240 x 2 = 153,600 bytes
File size (bytes) = frame size x frame rate x t
= 153600 x 25 x 29 = 111360000 bytes
File size (MB) = 111360000/1024 x 1024
= 10.6 MB
Example:

18. Video Compression
 The video compression/decompression programs are used so that video can fit on a
single CD and the speed of transferring video from a CD to the computer can be
increased.
 Let us say that a sequence of 25fps video is about 25MB.
 CD-ROM transfer rate is calculated as follows:
 1X= 150KB per second
 10X=1.5 MB per second
 100X= 15 MB per second
 To overcome large video size, CODECS were developed.
Compresses
when saved
CODEC
File format used
such as: Avi,
Mpeg, Mov
Decompresses
when needed for
display

19. Video Compression
 Digital video compression schemes or codecs is the algorithm used to compress
(code) a video for delivery.
 The codec then decodes the compressed video in real-time for fast playback.
 Streaming audio and video starts playback as soon as enough data has transferred to
the user’s computer to sustain this playback.
FULL
VIDEO
Taken from the CD
into memory buffer
DISPLAY ON
SCREEN
MEMORY BUFFER

20. Video Compression
 Two types of COMPRESSION:
 Lossless compression.
 Preserves the exact image throughout the compression and
decompression process. E.g: text images is to identify
repeating words and assign them a code.

21. Video Compression
 Two types of COMPRESSION:
 Lossy compression.
 Eliminates some of the data in the image and therefore
provides greater compression ratios than lossless
compression.
 Applied to video because some drop in the quality is not
noticeable in moving images.

22. Video Compression
 Two types of CODEC (lossy):
 Spatial compression
 a digital compression of video data that compresses the size of
the video file by compressing the image data of each frame
 Compression is done by removing redundancy from data in
the same frame.

23. Video Compression
 Two types of CODEC:
 Temporal compression
 a digital compression of video data that uses similarities of
sequential frames over time to determine and store only the image
data that differs from frame to frame.
 Compression is done by removing similarity between successive
video frames

24. Video Compression
 Flavors of file formats brand to choose:
 Microsoft’s AVI format
 QuickTime
 MPEG
 Div-X
 Wmv (Windows Media Video)

25. Video Compression
 Standards have been established for compression
programs, including JPEG (Joint Photographic Experts
Group) and MPEG (Motion Picture Experts Group).

26. JPEG (Spatial)
 Often areas of an image (especially backgrounds) contain
similar information.
 JPEG compression identifies these area and stores them as blocks
of pixels instead of pixel by pixel reducing the amount of
information needed to store the image.
 These program reduce the file size of graphic images by
eliminating redundant information.

27. MPEG (Temporal)
 The changes in the image from frame to frame.
 Key frames are identified every few frames the
changes that occur from key frame.
 Provide greater compression ratios than JPEG.
 Initially, it requires extra hardware for multimedia.

28. Video Hardware and Software
VCR
Video Overlay Board /
Video Capture Card
Video digital
Editing Software
MULTIMEDIA PC

29. Advantages of using Video
 Captures interest
 Increase retention
 Clarifies complex physical actions and relationships
 Can incorporate other media

30. Disadvantages of using Video
 Is expensive to produce
 Requires extensive memory and storage
 Requires special equipment
 Does not effectively illustrate abstract concepts and
static situations

31. H.W
 A video clip with size of 45 MB is found in the face book,
suppose your friend Taj is going to download it , and he is
using Zain Connect with bandwidth of 2 MB, calculate
the download time?