quicktime - 访问 QuickTime 电影轨道的 Edit Atom 的内容？

Question

有什么方法可以使用 QuickTime (C) API来获取 QuickTime Movie Track 的Edit Atom（即“edts”）的一般内容和它的Edit List Atom（即“elst” ）的内容？

目标是识别给定轨道中的任何编辑及其持续时间和开始时间。

在过去的两个小时里，我一直在检查 QuickTime 参考库（旧版和当前版），但无法识别任何 API 来实现这一点。

任何提示将不胜感激。

干杯，

\比约恩

Answer 1

回答我自己的问题：

轨道编辑列表的内容（如果有），即轨道中存在的编辑/片段可以通过GetTrackNextInterestingTime()API 函数（从 Movies.h 中提取的代码）确定：

/*
 *  GetTrackNextInterestingTime()
 *  
 *  Availability:
 *    Non-Carbon CFM:   in QuickTimeLib 2.5 and later
 *    CarbonLib:        in CarbonLib 1.0 and later
 *    Mac OS X:         in version 10.0 and later
 *    Windows:          in qtmlClient.lib 3.0 and later
 */
EXTERN_API( void )
GetTrackNextInterestingTime(
  Track        theTrack,
  short        interestingTimeFlags,
  TimeValue    time,
  Fixed        rate,
  TimeValue *  interestingTime,
  TimeValue *  interestingDuration);

通过在. nextTimeTrackEdit_nextTimeEdgeOKinterestingTimeFlags

对于您可能对轨道中存在的编辑感兴趣的大多数情况，您必须将返回interestingTime的轨道时间映射到媒体时间（如果您一直在检查轨道的编辑以确定可能的轨道偏移量）。

这是通过TrackTimeToMediaTime()API 函数完成的：

/*
 *  TrackTimeToMediaTime()
 *  
 *  Availability:
 *    Non-Carbon CFM:   in QuickTimeLib 2.5 and later
 *    CarbonLib:        in CarbonLib 1.0 and later
 *    Mac OS X:         in version 10.0 and later
 *    Windows:          in qtmlClient.lib 3.0 and later
 */
EXTERN_API( TimeValue )
TrackTimeToMediaTime(
  TimeValue   value,
  Track       theTrack);

编辑

将轨道时间转换为媒体时间的最先进方法是TrackTimeToMediaDisplayTime()：

/*
 *  TrackTimeToMediaDisplayTime()
 *  
 *  Summary:
 *    Converts a track's time value to a display time value that is
 *    appropriate to the track's media, using the track's edit list.
 *    This is a 64-bit replacement for TrackTimeToMediaTime.
 *  
 *  Discussion:
 *    This function maps the track time through the track's edit list
 *    to come up with the media time. This time value contains the
 *    track's time value according to the media's time coordinate
 *    system. If the time you specified lies outside of the movie's
 *    active segment or corresponds to empty space in the track, this
 *    function returns a value of -1. Hence you can use it to determine
 *    whether a specified track edit is empty.
 *  
 *  Parameters:
 *    
 *    value:
 *      The track's time value; must be expressed in the time scale of
 *      the movie that contains the track.
 *    
 *    theTrack:
 *      The track for this operation.  Your application obtains this
 *      track identifier from such functions as NewMovieTrack and
 *      GetMovieTrack.
 *  
 *  Result:
 *    The corresponding time in media display time, in the media's time
 *    coordinate system. If the track time corresponds to empty space,
 *    this function returns a value of -1.
 *  
 *  Availability:
 *    Non-Carbon CFM:   not available
 *    CarbonLib:        not available
 *    Mac OS X:         in version 10.4 (or QuickTime 7.0) and later
 *    Windows:          in qtmlClient.lib version 10.4 (or QuickTime 7.0) and later
 */
EXTERN_API( TimeValue64 )
TrackTimeToMediaDisplayTime(
  TimeValue64   value,
  Track         theTrack);