摘要
低延迟直播是视频直播中一个颇具挑战性的技术难点.文章从网络推流、首帧延迟、视频编码延迟三个角度进行延迟优化:首先依据网络状况自适应调整推流码率;其次实现关键帧缓存算法,优化首帧打开时间,使得首帧打开时间减少到2~4秒;然后改进帧内预测模式快速选择算法,通过降低候选模式个数减少编码复杂度,在视频质量基本不变的前提下使编码时间最多可降低约22%.最后基于以上三种优化策略设计实现屏幕直播系统并应用于课堂教学,满足课堂屏幕共享低延迟场景.
Low delay live is a challenging technical difficulty in video live broadcast.In this study,delay optimization is carried out from three perspectives:network push stream,first frame delay,and video coding delay.The details are as follows.Firstly,according to the network condition,the code rate of live pushing stream is adjusted adaptively.Secondly,the key frame caching algorithm is implemented to reduce the opening time of the first frame to 2~4 seconds.Then,a fast selection algorithm is improved for intra-frame prediction mode,the coding complexity is reduced by cutting down the number of candidate modes and the encoding time can be reduced by up to about 22%under the premise that video quality is basically unchanged.Finally,based on the above three optimization strategies,the screen live system is designed,implemented,and applied to classroom teaching to meet the low delay scenes of classroom screen sharing.
作者
付鹏斌
任衡
杨惠荣
FU Peng-Bin;REN Heng;YANG Hui-Rong(Faculty of Information Technology,Beijing University of Technology,Beijing 100124,China)
出处
《计算机系统应用》
2019年第9期81-87,共7页
Computer Systems & Applications
关键词
直播延迟
自适应推流
关键帧缓存
帧内预测
屏幕直播
live delay
adaptive push stream
keyframe cache
intra-frame prediction
screen live
