【作者】 李凡； 刘贵忠； 李智；

【Author】 Fan Li 1 Guizhong Liu 1+ Zhi Li1 1 (School of Electronics and Information Engineering, Xi’an Jiaotong University,Xi’an 710049)

【机构】 西安交通大学电子与信息工程学院信通系；

【摘要】 本文提出了一种新的实时MPEG视频在Internet中传输的错误抵抗方法。本文定义了帧重要性参数,用以表示每一帧对整个视频的不同重要性;根据每一帧的重要性不同,采用前向纠错编码,对具有不同帧重要性参数的视频包进行不同程度的保护。仿真结果表明,该方法获得了较好的传输性能和视频效果。更多还原

【Abstract】 It has become more promising challenging to provide adequate quality of service (QoS) for video stream transport over the Internet, especially for the real-time video stream. The current Internet works on best-effort service, and couldn’t provide QoS guarantee. Therefore, effective transmission control must be applied for improving the end-to-end video quality. The MPEG video compression technique is based on a macroblock structure, the motion compensation, and the conditional replenishment of macroblock. Frames in MPEG video can be divided into three types: intra (I), predictive (P) and bidirectionally (B). Because of the various encoding predictive methods, I, P and B frames have different importance degree for the video stream. Some studies focused on that, and proposed error resilience methods. They give unequal protection for I, P and B frames in order to improve the end-to-end video quality. Factually, frames with identical coding type may make unequal contribution to the video perceptual quality. They rely on the fact that the error concealment is performed in most video decoders to retrieve loss of information incurred in delivery. In this paper, we present an error resilience for real-time MPEG video stream over the Internet. First, we define the frame relative importance index (FRII) to estimate the contribution made by each frame to the video perceptual quality. The FRII of each frame is calculated by the compressed domain features, such as macroblock (MB) encoding bits, MB encoding types and motion vectors. The compressed domain method need not to fully decompress the video stream, and hence has lower complexity. Then, the unequal forward error correction (FEC) is applied for video packet transmission according to the FRII of each frame. The frame with higher FRII will be given more protection in delivery. Simulation results are presented to indicate good performances and significant improvement of the proposed approach.更多还原