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一分钟快速搭建 rtmpd 服务器: https://blog.csdn.net/freeabc/article/details/102880984
软件下载地址: http://www.qiyicc.com/download/rtmpd.zip
github 地址：https://github.com/superconvert/smart_rtmpd
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1. VP8 有两证类型的帧 http://www.faqs.org/rfcs/rfc6386.html
There are only two types of frames in VP8.Intraframes (also called key frames and, in MPEG terminology,I-frames) are decoded without reference to any other frame in asequence; that is, the decompressor reconstructs such framesbeginning from its "default" state. Key frames provide random access(or seeking) points in a video stream.Interframes (also called prediction frames and, in MPEG terminology,P-frames) are encoded with reference to prior frames, specificallyall prior frames up to and including the most recent key frame.Generally speaking, the correct decoding of an interframe depends onthe correct decoding of the most recent key frame and all ensuingframes. Consequently, the decoding algorithm is not tolerant ofdropped frames: In an environment in which frames may be dropped orcorrupted, correct decoding will not be possible until a key frame iscorrectly received.Intraframes 也叫 key frames ，类似于 h264 的 I 帧，Interframes 也叫 prediction frames， 类似于 h264 的 P 帧，VP8 没有 h264 的 B 帧
2. Golden Frame 和 AltRef Frame
prediction frames, called golden frames and altref frames(alternative reference frames). Blocks in an interframe may bepredicted using blocks in the immediately previous frame as well asthe most recent golden frame or altref frame. Every key frame isautomatically golden and altref, and any interframe may optionallyreplace the most recent golden or altref frame.这两个帧首先是 Key Frame ， Golden Frame 用于视频背景的更新，可以用来克服帧丢失， 是可以显示的。
AltRef Frame 只用于参考，不显示，质量高于普通帧，主要提升帧间预测的一些信息参考。此外还有一个 Last Frame ，
这三种帧提供了帧间预测的功能，类似于 h264 的 B 帧功能。
