MediaSetRate(IM: QC)

Inside Macintosh: QuickTime Components /

Chapter 10 - Derived Media Handler Components / Derived Media Handler Components Reference

Functions / General Data Management

MediaSetRate
The MediaSetRate function allows the Movie Toolbox to set your media's
playback rate.
pascal ComponentResult MediaSetRate (ComponentInstance ci, 
                                     Fixed rate);
ci
Identifies the Movie Toolbox's connection to your derived media handler.
rate
Contains a 32-bit, fixed-point number that indicates your media's new effective playback rate. This effective rate accounts for any master time bases that may be in use with the current movie. Positive values represent forward rates and negative values indicate reverse rates.

DESCRIPTION
The Movie Toolbox calls your derived media handler's MediaSetRate function whenever the movie's playback rate changes. The Movie Toolbox provides you with a new effective rate for your media. This effective rate accounts for any master time bases that may be in use with the current movie. Consequently, you may use this rate without having to further transform it.
You obtain the initial rate information from the effectiveRate field of the movie parameter structure that the Movie Toolbox provides to your MediaInitialize function.
Your derived media handler should support this function if you perform your
own scheduling. If you are doing your own scheduling (that is, you
have set the handlerNoScheduler flag to 1 in the flags parameter of the MediaSetHandlerCapabilities function--see page 10-36 for more information about this function), your media handler can use this function to determine when your media is playing, and the direction and rate of playback. This information can help you prepare for playback more efficiently.

RESULT CODES
Any Component Manager result code