相关疑难解决方法(0)

我使用下面的代码在视频上添加图像叠加,然后将新生成的视频导出到文档目录.但奇怪的是,视频旋转了90度.

- (void)buildTransitionComposition:(AVMutableComposition *)composition andVideoComposition:(AVMutableVideoComposition *)videoComposition
{
    CMTime nextClipStartTime = kCMTimeZero;
    NSInteger i;

    // Make transitionDuration no greater than half the shortest clip duration.
    CMTime transitionDuration = self.transitionDuration;
    for (i = 0; i < [_clips count]; i++ ) {
        NSValue *clipTimeRange = [_clipTimeRanges objectAtIndex:i];
        if (clipTimeRange) {
            CMTime halfClipDuration = [clipTimeRange CMTimeRangeValue].duration;
            halfClipDuration.timescale *= 2; // You can halve a rational by doubling its denominator.
            transitionDuration = CMTimeMinimum(transitionDuration, halfClipDuration);
        }
    }

    // Add two video tracks and two audio tracks. …