iOS AVVideoCompositionCoreAnimationTool：如何使用videoCompositionCoreAnimationToolWithAdditionalLayer

Question

我正在努力寻找有关如何使用

videoCompositionCoreAnimationToolWithAdditionalLayer

的任何文档。我一直在使用

videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer

，但它不支持 HDR 视频。

如果有人可以提供一个例子，将不胜感激。

Answer 1

除了animationTool还需要添加图层指令

CMPersistentTrackID trackId = [asset unusedTrackID];

AVMutableVideoCompositionLayerInstruction* effectlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstruction];
[effectlayerInstruction setTrackID: trackId];
[effectlayerInstruction setOpacity:1.0 atTime:kCMTimeZero];

videoInstruction.layerInstructions = @[effectlayerInstruction, videolayerInstruction]; //effectlayerInstruction should be first to not overlap by the video, make layer with bgColor clear

/// animationTool:
composition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithAdditionalLayer:layer asTrackID: trackId]; //trackId should be the same