如何在 iOS 上捕获的视频中添加水印[重复]

我想知道是否有人可以告诉我如何实现这一目标。如果一直在考虑几个解决方案：

1. 从捕获的视频创建单独的图像，然后将它们合并到每个图像中，然后创建一个新的 AVAsset...听起来有点复杂，您不觉得吗？

2. 合并2个视频，一个是透明的（带有水印的），另一个是用相机捕获的资产。

此代码是在视频上添加文本或字符串，保存视频后，您将在任何播放器上播放。 该代码的最大优点是提供带有声音的视频。所有内容都在一个代码中（即文本和图像）。

#import <AVFoundation/AVFoundation.h>

-(void)MixVideoWithText
{
    AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:url options:nil];
    AVMutableComposition* mixComposition = [AVMutableComposition composition];

    AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *clipAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    //If you need audio as well add the Asset Track for audio here

    [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:clipVideoTrack atTime:kCMTimeZero error:nil];
    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];

    [compositionVideoTrack setPreferredTransform:[[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] preferredTransform]];

    CGSize sizeOfVideo=[videoAsset naturalSize];

    //TextLayer defines the text they want to add in Video
    //Text of watermark 
    CATextLayer *textOfvideo=[[CATextLayer alloc] init];
    textOfvideo.string=[NSString stringWithFormat:@"%@",text];//text is shows the text that you want add in video.
    [textOfvideo setFont:(__bridge CFTypeRef)([UIFont fontWithName:[NSString stringWithFormat:@"%@",fontUsed] size:13])];//fontUsed is the name of font
    [textOfvideo setFrame:CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height/6)];
    [textOfvideo setAlignmentMode:kCAAlignmentCenter];
    [textOfvideo setForegroundColor:[selectedColour CGColor]];

    //Image of watermark 
    UIImage *myImage=[UIImage imageNamed:@"one.png"];
    CALayer layerCa = [CALayer layer];
    layerCa.contents = (id)myImage.CGImage;
    layerCa.frame = CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height); 
    layerCa.opacity = 1.0; 

    CALayer *optionalLayer=[CALayer layer];
    [optionalL addSublayer:textOfvideo];
    optionalL.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
    [optionalL setMasksToBounds:YES];

    CALayer *parentLayer=[CALayer layer];
    CALayer *videoLayer=[CALayer layer];
    parentLayer.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
    videoLayer.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
    [parentLayer addSublayer:videoLayer];
    [parentLayer addSublayer:optionalLayer];
    [parentLayer addSublayer:layerCa];

    AVMutableVideoComposition *videoComposition=[AVMutableVideoComposition videoComposition] ;
    videoComposition.frameDuration=CMTimeMake(1, 30);
    videoComposition.renderSize=sizeOfVideo;
    videoComposition.animationTool=[AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

    AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mixComposition duration]);
    AVAssetTrack *videoTrack = [[mixComposition tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
    instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];
    videoComposition.instructions = [NSArray arrayWithObject: instruction];

    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd_HH-mm-ss"];
    NSString *destinationPath = [documentsDirectory stringByAppendingFormat:@"/utput_%@.mov", [dateFormatter stringFromDate:[NSDate date]]];

    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
    exportSession.videoComposition=videoComposition;

    exportSession.outputURL = [NSURL fileURLWithPath:destinationPath];
    exportSession.outputFileType = AVFileTypeQuickTimeMovie;
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
    switch (exportSession.status)
    {
        case AVAssetExportSessionStatusCompleted:
            NSLog(@"Export OK");
            if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(destinationPath)) {
                UISaveVideoAtPathToSavedPhotosAlbum(destinationPath, self, @selector(video:didFinishSavingWithError:contextInfo:), nil);
            }
            break;
        case AVAssetExportSessionStatusFailed:
            NSLog (@"AVAssetExportSessionStatusFailed: %@", exportSession.error);
            break;
        case AVAssetExportSessionStatusCancelled:
            NSLog(@"Export Cancelled");
            break;
    }
  }];
}

显示保存视频后会出现的错误。

-(void) video: (NSString *) videoPath didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo 
{
    if(error)
        NSLog(@"Finished saving video with error: %@", error); 
}