iOS AVFoundation - 显示视频和导出的时间显示

Question

我想在视频上显示叠加显示并导出包含此显示的视频.我看了AVFoundation框架,AVCompositions,AVAssets等,但我仍然没有想到实现这一目标.有一个名为AVSynchronizedLayer的类可以让你动画与视频同步的动画,但我不想动画,我想要将时间显示叠加到视频的每一帧.有什么建议？

问候

Answer 1

像这样......

(注意:从一个更大的项目中淘汰,所以我可能偶然包含了一些不必要的部分).

您需要获取时钟/动画的CALayer,并将其设置为var myClockLayer(使用andimation工具使用1/3).

这也假设您的传入视频只有两个轨道 - 音频和视频.如果你有更多,你需要更仔细地设置"asTrackID:2"中的轨道ID.

AVURLAsset* url = [AVURLAsset URLAssetWithURL:incomingVideo options:nil];
AVMutableComposition *videoComposition = [AVMutableComposition composition];

AVMutableCompositionTrack *compositionVideoTrack = [videoComposition  addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipVideoTrack = [[url tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [url duration])  ofTrack:clipVideoTrack atTime:kCMTimeZero error:&error];

AVMutableVideoComposition* videoComposition = [[AVMutableVideoComposition videoComposition]retain];
videoComposition.renderSize = CGSizeMake(320, 240);
videoComposition.frameDuration = CMTimeMake(1, 30);
videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithAdditionalLayer:myClockLayer asTrackID:2];

AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30) );

AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:clipVideoTrack];
instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];

videoComposition.instructions = [NSArray arrayWithObject: instruction];

exporter = [[AVAssetExportSession alloc] initWithAsset:saveComposition presetName:AVAssetExportPresetHighestQuality] ;
exporter.videoComposition = videoComposition;
exporter.outputURL=url3;
exporter.outputFileType=AVFileTypeQuickTimeMovie;

[exporter exportAsynchronouslyWithCompletionHandler:^(void){}];