Aspect Ratio Concept

Use the parameters of Aspect Ratio provided by specifications.

• For MPEG2, please useaspect_ratio_information(Refer toISO-13818-2(MPEG2 Specification) page 45)
• For H264, please useaspect_ratio_idc(Refer toT-REC-H.264-200711-I!!PDF-E.pdfPage 346).
• aspect_ratio_idc specifies the value of the sample aspect ratio of the luma samples. Table E-1 shows the meaning of the code. When aspect_ratio_idc indicates Extended_SAR, the sample aspect ratio is represented by sar_width and sar_height. When the aspect_ratio_idc syntax element is not present, aspect_ratio_idc value shall be inferred to be equal to 0.  

Aspect Ratio of a Shape

The aspect ratio of a shape is the ratio ofits longer dimensiontoitsshorter dimension. It may be applied to two characteristic dimensions of a three-dimensional shape, such as the ratio of the longest and shortest axis, or for symmetrical objects that are described by just two measurements, such as the length and diameter of a rod.

For more detailed information, please refer tohttp://en.wikipedia.org/wiki/Aspect_ratio.51Testing软件测试网+cD2z%T DwZ6_"R

 51Testing软件测试网-z*VKunu"hF2y

Pixel Aspect Ratio (PAR)

Pixel aspect ratio (PAR), in computer graphics terminology, is a mathematical ratio that describes how the horizonal length of a pixel in an imaging system compares to its vertical height.

Most digital imaging systems describe an image as a grid of very small but nontheless square pixels. However, some imaging systems, especially those which must maintain compatibility with analog standard-definition, define image as a grid of rectangular pixels in which the width of the pixel is different that of its height. To describe this proportion, we state it in form of Pixel Aspect Ratio. For more detailed information, please refer tohttp://en.wikipedia.org/wiki/Pixel_aspect_ratio.51Testing软件测试网1m7u u9OOA L

 51Testing软件测试网6hNQ%?kv*|^

Image Aspect Ratio

Image aspect ratio: The aspect ratio of an image is its width divided by its height.51Testing软件测试网4j0?/Y(L:{Hl3V-GX1r2\

Aspect ratios are mathematically expressed as x :y (pronounced "x-to-y") and x×y (pronounced "x-by-y"). The most common aspect ratios used today in the presentation of films in movie theaters are 1.85:1 and 2.39:1. Two common videographic aspect ratios are 4:3 (1.33:1), universal for standard-definition video formats, and 16:9 (1.78:1), universal to high-definition television and European digital television. Other cinema and video aspect ratios exist, but are used infrequently. In still camera photography, the most common aspect ratios are 4:3 and 3:2, though other aspect ratios, such as 5:4, 7:5, and 1:1 (square format), are used.51Testing软件测试网:bF~5hD+T
For more detailed information, please refer tohttp://en.wikipedia.org/wiki/Aspect_ratio_(image).

Computer display standard

Computer display standard:Various computer display standards or display modes have been used in the history of the personal computer. They are often a combination of display resolution (specified as the width and height in pixels), color depth (measured in bits), and refresh rate (expressed in hertz). Associated with the screen resolution and refresh rate is a display adapter. Earlier display adapters were simple frame-buffers, but later display standards also specified a more extensive set of display functions and software controlled interface.51Testing软件测试网#L-z;Ov A-T

Until about 2003, most computer monitors had a 4:3 aspect ratio and some had 5:4. Between 2003 and 2006, monitors with 16:10 aspect ratios have become commonly available, first in laptops and later also in standalone monitors. Productive uses for such monitors, i.e. besides widescreen movie viewing and computer game play, are the wordprocessor display of two standard letter pages side by side, as well as CAD displays of large-size drawings and CAD application menus at the same time. The VESA industry organization has defined several standards related to power management and device identification. Ergonomy standards are set by the TCO.51Testing软件测试网
k#f OV/G4^F-K
For more detailed information, please refer tohttp://en.wikipedia.org/wiki/Computer_display_standard.

 51Testing软件测试网.pMK4bI@A

 51Testing软件测试网#eD?Z2[h eV$XU/i

Reference:51Testing软件测试网'{!|e8zc