Since the media of output usually support rasterised bitmap image only, a computer graphic image is always rasterised into a grid of pixels before being outputted onto the media of output. The property of computer graphics used by vector graphics enables the computer graphic image to be scaled up or down without losing resolution, while this is impossible to be done on bitmap image. Example of vector graphic image format is SVG. A vector graphics is computer graphic image that is made up of polygons and other shapes constructed by connecting lines and curve on specified 2D coordinate points. Examples of bitmap image file formats are JPEG, GIF, and PNG. Raster graphics is a bitmap image that made out of a matrix of small dots, called pixels.
In general, there are types of digital graphic pictures, namely raster graphics and vector graphics. However, the higher the image resolution, the bigger the image size required.
For both the media of output and digital graphic image, the more pixels mean the higher resolution and the better image quality. Since the construction and size of the pixel block depends on the media of output used, the mapping process is usually done by ethe media of output. 标签： scale ffmpeg stream frame ctx ret filter codec avġ、概述 此例子用ffmpeg的filter实现视频scale。 2、代码 /** * 最简单的基于FFmpeg的AVFilter例子（scale） * * 缪国凯（MK） * * * * * 本程序使用FFmpeg的AVfilter实现了视频的缩放功能。 * * */ #include "stdafx.Digital graphic pictures on a media of output are presented by mapping the pixel elements of graphic image to the tiny pixel blocks of the media of output.
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