2.2.1.12 X-StartupProfile

This header specifies a list of streaming bit rates, and for each bit rate it specifies the maximum amount of data that the audio and video decoders need and the time stamp of the ASF payload at which this maximum occurs. The client buffers at least the amount of data indicated by this header to prevent buffer underflow.

The information on this header is valid only during an initial time period during which the server is transmitting data faster than real time. The header specifies the first and last time stamp of the ASF payloads for which the information is valid.

The Rate, MaxBytes, Time, and ByteRate parameters on the X-StartupProfile header are arrays. This means that the first value in the Rate array corresponds to the first value in the MaxBytes array, and the second value in the Rate array corresponds to the second value in the MaxBytes array, and so on.

This header is defined for use only in responses sent to a client.<49>

The syntax of the X-StartupProfile header is defined as follows.

 X-StartupProfile= "X-StartupProfile: " XSP-Rate ";"
   XSP-MaxBytes ";" XSP-Time ";" XSP-STime ";" 
   XSP-LTime ";" XSP-MaxDTime ";" XSP-MaxDSTime ";"
   XSP-ByteRate ";" CRLF
  

Example:

 X-StartupProfile: Rate=10,12,15,20,30;
 MaxBytes=12874,9407,9086,8551,7482;Time=12512,34,34,34,34;
 StartTime=1694318962;LastTime=19521;MaxDiffTime=0;
 MaxDiffSndTime=0;ByteRate=30794,31469,31469,31469,31469;