本标准定义了一种传输协议，用于通过IP网络传输实时分段恒定可变比特率（VBR）MPEG-2传输流，包括或不包括用于从网络传输错误中恢复的前向纠错。根据ISO/IEC 13818-1:2007§2.4.2.2，分段恒定VBR传输流只能在考虑中的项目的PCR处变化。

This standard defines a transport protocol for the carriage of real-time piecewise constant variable bit rate (VBR) MPEG-2 Transport Streams over IP networks, either with or without Forward Error Correction for recovery from network transmission errors. A piecewise constant VBR transport stream can only vary at the PCRs of the program under consideration per ISO/IEC 13818-1:2007 § 2.4.2.2.