Inside Macintosh: QuickTime /

Chapter 2 - Movie Toolbox / Movie Toolbox Reference

Functions That Modify Movie Properties / Finding Interesting Times

GetTrackNextInterestingTime

The GetTrackNextInterestingTime function searches for times of interest in a track.

pascal void GetTrackNextInterestingTime (Track theTrack, 
                                 short interestingTimeFlags,
                                 TimeValue time, Fixed rate, 
                                 TimeValue *interestingTime,
                                 TimeValue *interestingDuration);

theTrack

Specifies the track for this operation. Your application obtains this track identifier from such Movie Toolbox functions as NewMovieTrack and GetMovieTrack (described on page 2-136 and page 2-188, respectively).

interestingTimeFlags

Specifies the search criteria. Note that you may set only one of the nextTimeMediaSample, nextTimeMediaEdit, nextTimeTrackEdit and nextTimeSyncSample flags to 1. The following flags are available (set unused flags to 0):

nextTimeMediaSample

Searches for the next sample in the track's media. Set this flag to 1 to search for the next sample.

nextTimeMediaEdit

Searches for the next group of samples in the track's media. Set this flag to 1 to search for the next group of samples.

nextTimeTrackEdit

Searches for the media sample that corresponds to the next entry in a track's media edit list. The end of the track is considered an empty edit. Set this flag to 1 to search for the next track edit.

nextTimeSyncSample

Searches for the next sync sample in the track's media. Set this flag to 1 to search for the next sync sample.

Sync samples do not rely on preceding frames for content. Some compression algorithms conserve space by eliminating duplication between consecutive frames in a sample.

nextTimeEdgeOK

Instructs the Movie Toolbox that you are willing to receive information about elements that begin or end at the time specified by the time parameter. Set this flag to 1 to accept this information.

This flag is especially useful at the beginning or end of a track. The function returns valid information about the beginning and end of the track.

nextTimeIgnoreActiveSegment

Instructs the Movie Toolbox to look outside of the active segment for samples that meet the search criteria. Set this flag to 1 to search outside of the active segment.

time

Specifies a time value that establishes the starting point for the search. This time value must be expressed in the movie's time scale.

rate

Contains the search direction. Negative values cause the Movie Toolbox to search backward from the starting point specified in the time parameter. Other values cause a forward search.

interestingTime

Contains a pointer to a time value. The Movie Toolbox returns the first time value it finds that meets the search criteria specified in the flags parameter. This time value is in the movie's time scale.

If there are no times that meet the search criteria you specify, the Movie Toolbox sets this value to -1.

Set this parameter to nil if you are not interested in this information.

interestingDuration

Contains a pointer to a time value. The Movie Toolbox returns the duration of the interesting time. This time value is in the movie's time coordinate system. Set this parameter to nil if you do not want this information--in this case, the function works more quickly.

ERROR CODES

invalidTrack	-2009	This track is corrupted or invalid
invalidTime	-2015	This time value is invalid