1. What are the common format for video files?
What are the difference between VCD and DVD?
How can we produce video files to fit our needs?

2. Activity --- Video Editing

3. 5.1 Different Video Attributes
Video Standards
Different countries use different video standards for broadcasting
Video standard
Full name
Countries
PAL
Phase Alternate Line
The United Kingdom, most countries in Europe, Hong Kong, China, Singapore, Australia
NTSC
National Television Standards Committee
The United States, Japan, Taiwan
SECAM
Sequential Colour And Memory
France, Russia
TV display standards in different countries

4. 5.1 Different Video Attributes
Frames
Digitized video consists of a sequence of frames
Slightly different frames are displayed successively at high speed → continuous motion
Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Frame 6 Frame 7 Frame 8
Frame 9 Frame 10 Frame 11 Frame 12 Frame 13 Frame 14 Frame 15 Frame 16
A video actually consists of individual frames

5. 5.1 Different Video Attributes
Frame Size
The width and height of individual frames
Larger frame size → higher video quality → larger file size
Aspect ratio
the ratio of the video width to its height
What are the common aspect ratio used?
4:3
16:9

6. 5.1 Different Video Attributes
Frame size
Aspect ratio
Application
720 × 576
5 : 4
PAL DVD
480 × 576
5 : 6
PAL SVCD
352 × 288
11 : 9
PAL VCD
240 × 180
4 : 3
Web video
160 × 120
Web video or video mail
What are the frame size of TVs?
Traditional TV: 500 x 375
LCD/Plasma TV (32”): 1366 x 768
HD TV: 1920 x 1080(i./p)

7. 5.1 Different Video Attributes
Colour Depth
Each video frame is composed of pixels arranged in a rectangular grid
The colour depth of each pixel specifies the number of bits used to store colour information
Most video has 24-bit colour depth

8. 5.1 Different Video Attributes
Frame Rate
The number of video frames displayed on the screen in one second
Measured in frames per second (fps)
Higher frame rate (above 24 fps) → smoother motion
Frame rate (fps)
Multimedia system 30
NTSC TV 25
PAL TV 24
Movie films 15
Computer video or animation (such as Flash movies) 12

9. 5.1 Different Video Attributes
Effect of frame rate

10. 5.1 Different Video Attributes
Bit Rate (Encoding bit rate)
Determines the number of bits used to store one-second video
Can also be regarded as the number of bits passing through a particular point in a video stream
Measured in bits per second (bps)
The idea of video bit rate. The bit rate of video stream B is double of that of stream A.

11. 5.1 Different Video Attributes
Bit Rate (encoding bit rate)
Increasing bit rate → higher quality → larger file size
Choice of bit rate depends on user’s network connection speed
Low bit rate causes substantial quality loss
Bit rate: 20 kbps
File size: 56 KB
Bit rate: 50 kbps
File size: 127 KB
Bit rate: 100 kbps
File size: 274 KB
Bit rate: 450 kbps
File size: 1,113 KB
increasing bit rate
increasing quality
Increasing file size

12. 5.1 Different Video Attributes
The following videos have different bit rate, can you see the different?
80 kbps
700 kbps

13. 5.1 Different Video Attributes
Video File Size (uncompressed)
Can be estimated by the formula,
Video file size
Frame size
Colour depth
Frame rate
Duration × =
Consider a ten-second DVD frame size video clip (without audio), the uncompressed file size is:
(720 × 576) pixels/frame × 24 bits/pixel × 25 frames/second × 10 seconds
= 2,488,320,000 bits
= 311,040,000 bytes
= MB

14. 5.1 Different Video Attributes
Codec (Compressor and Decompressor)
The software used to compress and decompress video files
Compression reduces the storage space and the video access time
Original video
Compression
Compressed video
Decompression
Storage
Decompressed video (playback)
This step requires the appropriate codec installed on user’s computer

15. 5.1 Different Video Attributes
Codec (Compressor and Decompressor)
Most codecs are lossy
Final file size governed by a quality factor and encoding bit rate
Some common codecs
MPEG-1, MPEG-2, MPEG-4
Windows Media Video
DivX
RealVideo
Intel Indeo®Video
Cinepak Codec by Radius

16. 5.3 Common Video File Formats
Audio Video Interleave (AVI)
Native Windows video format developed by Microsoft
Data storage
Video data and audio data are stored in an interleaved manner
Improves the synchronization of audio and video playing
The structure of an AVI file

17. 5.3 Common Video File Formats
Audio Video Interleave (AVI)
Large file size in uncompressed format
Supports many codecs
The same 15-second AVI video in 3 formats
AVI (MPEG-4 codec)
File size: 3.28 MB
AVI (Cinepak Codec by Radius)
File size: 13.1 MB
AVI (uncompressed)
File size: 111 MB

18. 5.3 Common Video File Formats
Motion Picture Experts Group (MPEG, MPG)
A lossy compression file format
Preserves video quality yet supports high compression ratio
Stores only changes between successive frames, not all the image information of every individual frame → high compression 1 2

19. 5.3 Common Video File Formats
Motion Picture Experts Group (MPEG, MPG)
A family of compression standards
Standard
Maximum resolution
Encoding bit rate
Application
MPEG-1 (1992)
352 × 288 (PAL)
352 × 240 (NTSC)
1.5 Mbps
Video CDs, interactive CD-ROMs and MPEG-1 Audio Layer-3 music
MPEG-2 (1994)
720 × 576 (PAL)
720 × 480 (NTSC)
Varying up to 4 Mbps
DVDs and digital TV broadcast
MPEG-4 (1998) -
From 64 kbps up to 4 Mbps
Video in digital camera mobile phone, iPod and QuickTime
MPEG-4 can be as good as MPEG-2, but an MPEG-4 video is of a smaller file size and at a lower bit rate

20. 5.3 Common Video File Formats
Windows Media Video (WMV, ASF)
A streaming compressed video format developed by Microsoft
Can be played by Windows Media Player
Can be created with Windows Movie Maker
Windows Media Player
Windows Movie Maker

21. 5.3 Common Video File Formats
RealVideo (RV, RM)
A proprietary compressed streaming audio format developed by RealNetworks
Can be played by RealPlayer
RealProducer can encode video in other file formats with various bit rate.
Example 1
Example 2

22. 5.3 Common Video File Formats
RealVideo support video streaming
a user does not have to wait to download the whole video file before watching it
Without streaming
With streaming

23. 5.3 Common Video File Formats
QuickTime (MOV)
A streaming compressed multimedia file format on Macintosh computers
Can store text, still images and animation
Can be played with QuickTime Player
QuickTime Player
QuickTime pro

24. 5.3 Common Video File Formats
QuickTime VR
support virtual reality (VR) format
can display 360º panoramas of scenic
Example 1
Example 2
Example 3
QuickTime VR

25. Video capturing device
5.2 Capture Digital Video
Concept
To capture digital video, it is necessary to have
A capturing device (a camcorder)
A storage medium
Video encoding hardware and software
Video capturing device
Storage medium
Video encoding hardware and software

26. 5.2 Capture Digital Video Examples Video capturing devices
DV camcorder (or Handycam)
Digital camera
Webcam
Video encoding hardware
Video capture card
An external video capturing device
DVD-recorder
IEEE 1394 (firewire/i-link)
Video capturing and editing software is usually bundled with the hardware product

27. 5.2 Capture Digital Video Examples
A video capture card (top left) and an external video capturing device (bottom left) from Pinnacle. Moviestar, the video capturing and editing software, is bundled with the capturing hardware (right).

28. 5.4 Simple Video Editing
Common video editing techniques
trimming (cutting) video clips
adding titles
adding filters
adding transitions
importing still images
adding background music

29. END