2.2.1.4.6 client-lag

This token indicates to the server the amount of time, in milliseconds, by which the client can be lagging behind the server as a result of predictive streaming playlist changes. The server SHOULD then slow down the pushing of headers to the client by the smallest of the amount specified and 15000 milliseconds to ensure that the client does not fall too far behind.

Lag is defined as the amount of data queued on the client that is not intended for buffering. For example, if the client still has 5 seconds left to render from a playlist entry but the server has already streamed the first 7 seconds of the next playlist entry, and the client's network buffer is 3 seconds, the lag is 5 + 7 - 3 = 9 seconds. Under normal circumstances, the lag is expected to be zero, but implementation-specific issues can result in a nonzero lag.

This token is defined for use only in requests sent to a server with a version greater than or equal to 5.0 (as specified by the server in the Server header). The server MAY ignore the value specified by this token.<21>

The value MUST be an integer in the range from 0 through 4,294,967,295.

The syntax of the client-lag token is defined as follows.

 client-lag      = "client-lag=" 1*10DIGIT

Example:

 Pragma: client-lag=250