WEBRTC FEC/NACK 前向纠错码

转自:http://www.cnblogs.com/lingyunhu/p/rtc55.html

文档:
webrtc FEC方案详细介绍
https://static.googleusercontent.com/media/research.google.com/zh-CN//pubs/archive/41611.pdf


创业公司方案:
http://www.mediapro.cc/rtp%E6%8A%97%E4%B8%A2%E5%8C%85%E4%BC%A0%E8%BE%93%E6%96%B9%E6%A1%88/


本文主要分析webrtc中的抗丢包与带宽自适应原理,文章来自博客园RTC.Blacker,欢迎关注微信公众号blacker,更多详见www.rtc.help

 

文章内容主要来自中国电信北京研究院丁博士在上周六的技术交流会上的演讲内容,之前我们有在公众号上介绍过这个技术交流会,详见:http://mp.weixin.qq.com/s?__biz=MzA5ODMzMjE1NQ==&mid=401152241&idx=1&sn=38dd10e369d3f8e308a6086e84984072&scene=23&srcid=1219MtQx3dqOaQZo9L2emdBH#rd

从结果来看这种技术交流会还是挺有料的,主要是技术人员在分享技术,所以我们后面会将其他演讲嘉宾的资料也一并整理好发上来。

 

 实时通讯中为了保证传输速度我们的通讯协议一般采用udp,但是这样会带来丢包的问题,加上实际网络状况的复杂性,都会带来丢包,这样严重影响了音视频通话质量,如果保证在这种不稳定的网络状况到得到较好的通话质量呢?这就是本文主要介绍的三种技术:NACK,FEC和网络带宽自适应。

 

先看这三个术语的名词解释:

FEC:前向纠错也叫前向纠错码(Forward Error Correction简称FEC),是增加数据通讯可信度的方法。在单向通讯信道中,一旦错误被发现,其接收器将无权再请求传输。FEC 是利用数据进行传输冗余信息的方法,当传输中出现错误,将允许接收器再建数据。

 

NACK:a negative-acknowledge character (NAK or NACK)

In telecommunications, NACK is a transmission control character sent by a station as a negative response to the station with which the connection has been set up.

In Binary Synchronous Communications protocol, the NAK is used to indicate that a transmission error was detected in the previously received block and that the receiver is ready to accept retransmission of that block.

In multipoint systems, the NAK is used as the not-ready reply to a poll.

 

网络带宽自适应:这个比较好理解,按照一定的算法根据网络带宽状况,动态调整码率,以保持良好通话质量!

 

以下截图来自博士的pdf文档,由kelly进行整理:

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分类:  webrtc
标签:  webrtc android ios

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