关于视频合成的调研
对于AVFoundation的理解
1. AVMutableComposition(音视频组合轨道)相当于一个容器,是总的音视频混合API
AVMutableComposition *mainComposition =[ [AVMutableComposition alloc]init];
2. AVMutableCompositionTrack 创建对应的音视频轨道
//可变音视频轨道添加一个 视频通道
AVMutableCompositionTrack*compositionVideoTrack = [mainComposition addMutableTrackWithMediaType:AVMediaTypeVideopreferredTrackID:kCMPersistentTrackID_Invalid];
//可变音视频轨道添加一个 音频通道
AVMutableCompositionTrack*compositionAudioTrack = [mainComposition addMutableTrackWithMediaType:AVMediaTypeAudiopreferredTrackID:kCMPersistentTrackID_Invalid];