我想从我的 iOS 应用程序中编辑视频。我想要一些关于语言字幕的源视频文本。然后我想保存覆盖了该文本的视频。文字不仅仅是显示目的。但是当我打开编辑的视频时，它会显示更新的视频。
这在 iOS 应用程序中是否可行？如果是这样，怎么做？
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11435 次
3 回答
11
- (void)addAnimation
{
NSString *filePath = [[NSBundle mainBundle] pathForResource:videoName ofType:ext];
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:[NSURL fileURLWithPath:filePath] 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 = CFBridgingRetain(@"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];
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 ) {
dispatch_async(dispatch_get_main_queue(), ^{
[self exportDidFinish:assetExport];
});
}
];
}
-(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];
}
于 2013-03-09T07:08:32.357 回答
2
一种方法是将您的文本覆盖创建为 CoreAnimation CATextLayer，将其附加到 AVAssetExportSession 的 videoComposition，然后导出您的视频。生成的视频将在其上渲染叠加层。
这带来了一些好处：
- 您不必停留在 CATextLayer - 您可以构建包含 CAGradientLayer、CAShapeLayer 等的 CALayer 树。
- 作为核心动画层，它们的许多属性都是可动画的，因此您可以免费在视频中获得流畅的 iOS 风格动画。
听起来不错，对吧？有一点副作用：根据您使用的导出预设，您的视频将不可避免地以恒定帧速率重新编码 - 对我来说是 30fps。为了保持较小的文件大小，我故意通过省略冗余帧来降低帧速率，所以为了静态横幅，这对我来说是个大问题。
有一些名为 AVEditDemo 的 Apple 示例代码演示了此功能等。这里有找到它的说明。
于 2012-04-18T09:39:26.000 回答
1
使用 Chaitali Jain 代码，新视频将在没有音频的情况下保存。有人对这个问题有想法吗？谢谢！
于 2014-10-05T08:35:55.593 回答