带宽约束下FGS视频传输非均等错误保护

为了在带宽约束的丢包信道下获得最小的视频传输失真，提出一种基于MPEG-4精细粒度可扩展（FGS）编码的非均等错误保护（ULP）策略.该策略采用前向冗余纠错（FEC）方法进行错误保护，并根据FGS视频增强层之间存在的不同重要性, 对不同的增强层分配不同速率的冗余数据.重要性高的层获得更强的错误保护，而重要性低的层获得较弱的错误保护.建立了平均网络丢包概率和FGS视频率失真之间的关系模型，设计了优化的FEC数据分配算法.在网络仿真器（NS-2）中的模拟结果表明，该错误保护策略可以有效地减少视频失真以及视频质量波动，在10%的平均丢包概率下，可以获得1.5dB的质量提高.

Unequal loss protection for FGS video transmission under bandwidth constrained channel

To minimize the video transmission distortion on a bandwidth-limited network path with packet loss,an unequal loss protection(ULP) strategy was proposed for MPEG-4 fine granularity scalability(FGS) coding video stream.Video data were protected using forward error correction(FEC) scheme in the strategy.By exploiting the different significance existing in FGS video enhancement layers, different number of redundant data was allocated for different enhancement layers.Strongest protection was assigned for the most significant layers while weaker protection was assigned for the less significant layers.A relationship model of FGS video rate-distortion and average packet loss ratio was established,the optimal FEC data allocation algorithm was designed.Simulation results in network simulator(NS-2) show that the proposed error protection strategy can effectively reduce the video distortion and the variation of video quality.The strategy can achieve 1.5 dB gains under average packet loss ratio of 10%.