说明：  这是RFC3894原文文档，文档详细说明了H.264码流如果打包成RTP包。如果需要做H.264码流的实时传输，这是一篇必读的文章。
(This is the original document RFC3894, the document details the H.264 bitstream into RTP packets if the packaging. If you need to do real-time H.264 bitstream transmission, this is a must-read article.)