有保证的服务品质包含三种参数：封包传输延迟、封包延迟变异，以及封包遗失率。

Guaranteed QoS includes three basic parameters: packet transfer delay, packet delay variation and packet loss rate.

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传送端根据以变动框架长度为基础之 遗失率估算法，来估算目前网路上封包 遗失的状况，并以此作为切换高低音质档案的依据。

The sender tracks the packet loss status according to the algorithm-loss rate estimation based on variable frame size and switches two audio sample files in accordance with packet loss status.

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