对DVB Over IP应用来说，如何传送用可变比特率（VBR）压缩的MPEG-2传输流格式的视频是一个重要的问题。其中以传统的恒定速率（CBR）方式传送VBR视频时，接收端需要较大的缓存和开始延时时间；而另一种新的采用PCR协助的恒定速率（PCBR）传送方式，则是以较高的传输速率和以牺牲码率的稳定性来减少缓存需求。为了平衡传输速率和接收端缓存需求，在PCBR基础上，提出了一种称为IPCBR的改进的视频流传送方法。通过实验证明，该新方法与传统的CBR传送方式相比，不仅可降低缓存需求，而且与PCBR方式相比，又具有较高的稳定性和带宽利用率，并克服了PCBR丢包率较高的问题。同时由于该算法特别针对DVB Over IP，具有较强的实用性。且有利于Internet TV业务拓展。

For application of DVB Over IP,one important issue is about how to transmit compressed variable bit rate(VBR) MPEG-2 transport stream video.Transmitting compressed VBR video with traditional constant bit-rate(CBR)service requires a large buffer at the end.Another new transmission schemes called PCR-assist CBR which reduces the buffer requirement at the cost of higher transmission rate and low stability.To balance the transfer rate and the need for buffer in receiver,this paper presents an improved algorithm of transmitting transport streams called IPCBR which is based on PCBR.Experiments show that compared with traditional constant bit-rate service,the algorithm reduces the buffer requirement,provides high stability and high use of bandwidth as well as overcomes the problem of packet loss.Besides,the algorithm focuses on DVB over IP, so it has high practicability and also is valuable for developing new operation of Internet TV.