android高通视频硬编解码的样例代码

android高通视频硬编解码的样例代码

H.264编码, 视频监控的必选

H264编码开源代码 Video Usability Information (VUI) Guide by Christian Heine ( sennindemokrit at gmx dot net ) 1. Sample Aspect Ratio ----------------------- * What is it? The Sample Aspect Ratio (SAR) (sometimes called Pixel Aspect Ratio or just Pel Aspect Ratio) is defined as the ratio of the width of the sample to the height of the sample. While pixels on a computer monitor generally are "square" meaning that their SAR is 1:1, digitized video usually has rather odd SARs. Playback of material with a particular SAR on a system with a different SAR will result in a stretched/squashed image. A correction is necessary that relies on the knowledge of both SARs. * How do I use it? You can derive the SAR of an image from the width, height and the display aspect ratio (DAR) of the image as follows: SAR_x DAR_x * height ----- = -------------- SAR_y DAR_y * width for example: width x height = 704x576, DAR = 4:3 ==> SAR = 2304:2112 or 12:11 Please note that if your material is a digitized analog signal, you should not use this equation to calculate the SAR. Refer to the manual of your digitizing equipment or this link instead. A Quick Guide to Digital Video Resolution and Aspect Ratio Conversions http://www.iki.fi/znark/video/conversion/ * Should I use this option? In one word: yes. Most decoders/ media players nowadays support automatic correction of aspect ratios, and there are just few exceptions. You should even use it, if the SAR of your material is 1:1, as the default of x264 is "SAR not defined".

quadrature signal

在这节复习中，我们回顾一下连续时间和离散时间卷积，以及拉普拉斯和Z 变换。在本科 生课程中，你可能已经看到了这些概念，在这里我们处理单个信号和。这些概念 可以扩展到信号向量的情况，例如，但是现在，我们更应该注 意乘法的次序。例如，下面所描述的卷积中包括向量或矩阵时，是不可交换的，但是当x 和h 是单个信号时，是可以交换的。