1. Chapter 6 Fundamentals of Digital Video
Part 2
Basic Terminiology

2. In this lecture, you will learn:
These basic terminology in digital video: frame size frame aspect ratio pixel aspect ratio timecode

3. Sampling and Quantization of Motion
Temporal:
sampling rate:
how frequent you take a snapshot of the motion
frame rate
higher sampling rate: higher frame rate
higher frame rate  more frames for the same duration  larger file size

4. Sampling and Quantization of Motion
Each snapshot: a frame
an image
digitized based on the same concepts of sampling and quantization of images

5. Frame Size
Resolution of the frame image Measured in pixel dimensions No ppi setting: Unlike digital images, there is no pixel per inch (ppi) setting for video because video is not intended for print but for on screen display.

6. Frame Size Examples Frame size NTSC standard definition
720 x 480 pixels
high definition HDV format
1280 x 720 pixels
1440 x 1080 pixels
PAL
720 x 576 pixels

7. Frame Aspect Ratio
the ratio of a frame's viewing width to height NOT equivalent to ratio of the frame’s pixel width to height.

8. Frame Aspect Ratio Examples
4:3
16:9
Example:
Standard definition NTSC standard format
Examples:
Standard definition NTSC wide-screen format
High definition digital video
High definition TV

9. Ratio Does Not Match Up?
Frame size of a NTSC standard definition DV frame: 720 x : 480 = 3 : 2 NOT 4 : 3 or 16 : 9 This is because the pixels are not square!

10. Pixel Shapes
Digital images: square pixels Digital video: may not be square pixels

11. Pixel Aspect Ratio Pixel Aspect Ratio Pixel Shape 1 square < 1 tall
Ratio of pixel width : pixel height
Pixel Aspect Ratio
Pixel Shape 1
square
< 1
tall
> 1
wide

12. Pixel Aspect Ration Examples
Video Format
Pixel Aspect Ratio
Standard format of standard definition
(e.g. standard format of the non-blu-ray movies DVD)
0.9
Wide-screen format of standard definition
(e.g. wide-screen format of the non-blu-ray movies DVD)
1.2
HDV 720p,
QuickTime movies
1.0
HDV 1080i and 1080p
1.333

13. Let's see if the ratios match up

14. Standard Format Standard Definition
Pixel aspect ratio = 0.9 Frame size = 720  480 Frame aspect ratio = 720  0.9 : 480 = 648 : 480  4 : 3

15. Wide-screen Format Standard Definition
Pixel aspect ratio = 1.2 Frame size = 720  480 Frame aspect ratio = 720  1.2 : 480 = 864: 480  16 : 9

16. HDV 720p
Pixel aspect ratio = 1.0 Frame size = 1280  720 Frame aspect ratio = 1280  1.0 : 720 = 1280 : 720 = 16 : 9

17. HDV 1080i and 1080p
Pixel aspect ratio = Frame size = 1440  1080 Frame aspect ratio = 1440  : 1080  1920 : 1080 = 16 : 9

18. pixel aspect ratio
Video image will be distorted if it is displayed on a system with a different pixel aspect ratio.

19. For a video of pixel aspect ratio of 1
Displayed correctly on a system of pixel aspect ratio of 1
Displayed incorrectly on a system of pixel aspect ratio of 0.9.
The image looks stretched vertically.

20. For a video of pixel aspect ratio of 1
Displayed correctly on a system of pixel aspect ratio of 1
Displayed incorrectly on a system of pixel aspect ratio of 1.2.
The image looks stretched horizontally.

21. For a video of pixel aspect ratio of 0.9
Displayed correctly on a system of pixel aspect ratio of 0.9
Displayed incorrectly on a system of pixel aspect ratio of 1.
The image looks slightly stretched horizontally.

22. For a video of pixel aspect ratio of 0.9
Displayed correctly on a system of pixel aspect ratio of 0.9
Displayed incorrectly on a system of pixel aspect ratio of 1.2.
The image looks stretched horizontally.

23. For a video of pixel aspect ratio of 1.2
Displayed correctly on a system of pixel aspect ratio of 1.2
Displayed incorrectly on a system of pixel aspect ratio of 0.9.
The image looks stretched vertically.

24. For a video of pixel aspect ratio of 1.2
Displayed correctly on a system of pixel aspect ratio of 1.2
Displayed incorrectly on a system of pixel aspect ratio of 1.0.
The image looks slightly stretched vertically.

25. Distortion Pixel Apect Ratios Distortion
video frame's = display system's
none
video frame's < display system's
stretched horizontally
video frame's > display system's
stretched vertically

26. Counting Time in Digital Video
Timecode: to number frames
SMPTE (Society of Motion Pictures and Television Engineers) video timecode
number frames in hours, minutes, seconds, and frames
drop-frame timecode
non-drop-frame timecode

27. Drop-frame Timecode
Example: 00:02:51;20 or 00:02:51.20 Video time is 0 hours, 2 minutes, 51 seconds, and 20 frames Use semi-colons (not colons) Preferable for the NTSC system

28. Drop-frame Timecode
Does NOT mean dropping or removing frames from the video NTSC video is fps, not exactly 30 fps Drop-frame timecode renumbers frames to make the timecode more accurately represent the video time based on fps It’s able to do this by dropping frames. The specific pattern drops the first two frames of every minute except every tenth minute.

29. Non-Drop-frame Timecode
Example: 00:02:51:20 Video time is 0 hours, 2 minutes, 51 seconds, and 20 frames Use colons