如何在iOS中实时嵌入文字（标题）视频？

Question

我想在录制的视频中嵌入文本，然后将其保存在相机胶卷中。当这个视频是任何其他设备上播放这段文字应该显示

Answer 1

从这里：How can I add overlay text on a video, then re-encode it?

注意这不是更新的ARC，但应该给你的方法是一个好主意。 本示例包括添加图像和文本，使用iOS 7 API/CoreText可能会有更快的方式。

另外：像这样在视频上实时合成意味着将必要帧解压缩为位图，绘制文本，然后重新压缩视频。这是一项昂贵的操作，性能可能很差。这不适用于移动应用程序。

这是在视频文件中添加文本和图像的代码。这可能对您有所帮助。

AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:[NSURL fileURLWithPath:videoName] options:nil]; 

AVMutableComposition* mixComposition = [AVMutableComposition composition]; 

AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 

AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]; 

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

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

CGSize videoSize = [clipVideoTrack naturalSize]; 

UIImage *myImage = [UIImage imageNamed:@"29.png"]; 
CALayer *aLayer = [CALayer layer]; 
aLayer.contents = (id)myImage.CGImage; 
aLayer.frame = CGRectMake(videoSize.width - 65, videoSize.height - 75, 57, 57); 
aLayer.opacity = 0.65; 
CALayer *parentLayer = [CALayer layer]; 
CALayer *videoLayer = [CALayer layer]; 
parentLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height); 
videoLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height); 
[parentLayer addSublayer:videoLayer]; 
[parentLayer addSublayer:aLayer]; 

CATextLayer *titleLayer = [CATextLayer layer]; 
titleLayer.string = @"Text goes here"; 
titleLayer.font = @"Helvetica"; 
titleLayer.fontSize = videoSize.height/6; 
//?? titleLayer.shadowOpacity = 0.5; 
titleLayer.alignmentMode = kCAAlignmentCenter; 
titleLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height/6); //You may need to adjust this for proper display 
[parentLayer addSublayer:titleLayer]; //ONLY IF WE ADDED TEXT 

AVMutableVideoComposition* videoComp = [[AVMutableVideoComposition videoComposition] retain]; 
videoComp.renderSize = videoSize; 
videoComp.frameDuration = CMTimeMake(1, 30); 
videoComp.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]; 
videoComp.instructions = [NSArray arrayWithObject: instruction]; 

AVAssetExportSession *assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];//AVAssetExportPresetPassthrough 
assetExport.videoComposition = videoComp; 

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *documentsDirectory = [paths objectAtIndex:0]; 
NSString* VideoName = [NSString stringWithFormat:@"%@/mynewwatermarkedvideo.mp4",documentsDirectory]; 


//NSString *exportPath = [NSTemporaryDirectory() stringByAppendingPathComponent:VideoName]; 
NSURL *exportUrl = [NSURL fileURLWithPath:VideoName]; 

if ([[NSFileManager defaultManager] fileExistsAtPath:VideoName]) 
{ 
    [[NSFileManager defaultManager] removeItemAtPath:VideoName error:nil]; 
} 

assetExport.outputFileType = AVFileTypeQuickTimeMovie; 
assetExport.outputURL = exportUrl; 
assetExport.shouldOptimizeForNetworkUse = YES; 

//[strRecordedFilename setString: exportPath]; 

[assetExport exportAsynchronouslyWithCompletionHandler: 
^(void) { 
    [assetExport release]; 
    dispatch_async(dispatch_get_main_queue(), ^{ 
     [self exportDidFinish:assetExport]; 
    }); 
} 
]; 

[videoAsset release]; 

} 

-(void)exportDidFinish:(AVAssetExportSession*)session 
{ 
    NSURL *exportUrl = session.outputURL; 
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; 

    if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:exportUrl]) 
    { 
     [library writeVideoAtPathToSavedPhotosAlbum:exportUrl completionBlock:^(NSURL *assetURL, NSError *error) 
     { 
      dispatch_async(dispatch_get_main_queue(), ^{ 
       if (error) { 
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Video Saving Failed" 
                    delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
        [alert show]; 
       } else { 
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Video Saved" message:@"Saved To Photo Album" 
                    delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
        [alert show]; 
       } 
      }); 
     }]; 

    } 
    NSLog(@"Completed"); 
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"AlertView" message:@"Video is edited successfully." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
    [alert show]; 
    [alert release]; 

}