[英]How to extract images from a video?
谁能告诉我如何从视频中提取图像? 我到目前为止所尝试的是我遵循这些:
等等,在那之后我做了这个:
源代码:
- (void)viewDidLoad
{
videoPicker = [[UIImagePickerController alloc] init];
[videoPicker setDelegate:self];
videoPicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
NSArray *mediaTypesAllowed = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
videoPicker.mediaTypes = mediaTypesAllowed;
videoPicker.view.hidden = YES;
}
-(IBAction)imgPickerController
{
[self presentModalViewController:videoPicker animated:YES];
videoPicker.view.hidden = NO;
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
// e.g.
NSString *tempFilePath = [(NSURL *)[info valueForKey:UIImagePickerControllerMediaURL] absoluteString];
NSLog(@"didFinishPickingMediaWithInfo: %@",tempFilePath);
// e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp/capture/capturedvideo.MOV
tempFilePath = [tempFilePath substringFromIndex:16];
NSLog(@"didFinishPickingMediaWithInfo: %@",tempFilePath);
NSLog(@"===Try to save video to camera roll.===");
NSLog(@"UIVideoAtPathIsCompatibleWithSavedPhotosAlbum: %@",UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(tempFilePath)? @"YES":@"NO");
// Check if the video file can be saved to camera roll.
if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(tempFilePath))
{
// YES. Copy it to the camera roll.
UISaveVideoAtPathToSavedPhotosAlbum(tempFilePath, self, @selector(video:didFinishSavingWithError:contextInfo:),(__bridge_retained void *)tempFilePath );
}
[self dismissModalViewControllerAnimated:YES];
}
- (void)video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(NSString *)contextInfo
{
NSLog(@"didFinishSavingWithError--videoPath in camera roll:%@",videoPath);
NSLog(@"didFinishSavingWithError--videoPath in temp directory:%@",contextInfo);
// The thumbnail jpg should located in this directory.
NSString *thumbnailDirectory = [[contextInfo stringByDeletingLastPathComponent] stringByDeletingLastPathComponent];
// Debug info. list all files in the directory of the video file.
// e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp/capture
NSLog(@"%@",[contextInfo stringByDeletingLastPathComponent]);
NSLog(@"%@",[[[NSFileManager defaultManager] contentsOfDirectoryAtPath:[contextInfo stringByDeletingLastPathComponent] error:nil] description]);
// Debug info. list all files in the parent directory of the video file, i.e. the "~/tmp" directory.
// e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp
NSLog(@"%@",thumbnailDirectory);
NSLog(@"%@",[[[NSFileManager defaultManager] contentsOfDirectoryAtPath:thumbnailDirectory error:nil] description]);
///////////////////
// Find the thumbnail for the video just recorded.
NSString *file,*latestFile;
NSDate *latestDate = [NSDate distantPast];
NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:[[contextInfo stringByDeletingLastPathComponent]stringByDeletingLastPathComponent]];
// Enumerate all files in the ~/tmp directory
while (file = [dirEnum nextObject])
{
// Only check files with jpg extension.
if ([[file pathExtension] isEqualToString: @"jpg"])
{
NSLog(@"***latestDate:%@",latestDate);
NSLog(@"***file name:%@",file);
NSLog(@"***NSFileSize:%@", [[dirEnum fileAttributes] valueForKey:@"NSFileSize"]);
NSLog(@"***NSFileModificationDate:%@", [[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"]);
// Check if current jpg file is the latest one.
if ([(NSDate *)[[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"] compare:latestDate] == NSOrderedDescending)
{
latestDate = [[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"];
latestFile = file;
NSLog(@"***latestFile changed:%@",latestFile);
}
}
}
// The thumbnail path.
latestFile = [NSTemporaryDirectory() stringByAppendingPathComponent:latestFile];
NSLog(@"****** The thumbnail file should be this one:%@",latestFile);
UIImage *img = [[UIImage alloc] initWithContentsOfFile:latestFile];
UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(150, 150, 100, 100)];
[imgView setImage:img];
imgView.layer.borderWidth = 2.0;
[self.view addSubview:imgView];
// Your code ...
// Your code ...
// Your code ...
}
做完这一切后,我仍然到达了我想要到达的地方。我仍然无法获得图像。我现在被卡住了。请任何人帮助我!!!谢谢:)
从电影中提取缩略图的简单方法是使用MPMoviePlayerController
类及其- thumbnailImageAtTime:timeOption:
方法。
例如,您有一个文件路径 url:
NSURL *tempFilePathURL = ...;
MPMoviePlayerController *player = [[MPMoviePlayerController alloc] initWithContentURL: tempFilePathURL];
UIImage *thumbnail = [player thumbnailImageAtTime:THUMBNAIL_TIME timeOption:MPMovieTimeOptionExact];
[player release];
我在我的代码中使用了它并且它起作用了。
thumbImageAtTime:timeOption自 iOS 7.0 起已弃用。 这是一个替代方案
+ (UIImage *)extractFirstFrameFromFilepath:(NSString *)filepath
{
AVURLAsset *movieAsset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:filepath] options:nil];
AVAssetImageGenerator *assetImageGemerator = [[AVAssetImageGenerator alloc] initWithAsset:movieAsset];
assetImageGemerator.appliesPreferredTrackTransform = YES;
CGImageRef frameRef = [assetImageGemerator copyCGImageAtTime:CMTimeMake(1, 2) actualTime:nil error:nil];
return [[UIImage alloc] initWithCGImage:frameRef];
}
迅捷版
func getThumbOfVideo(fileURL: URL) -> UIImage? {
let movieAsset = AVURLAsset(url: fileURL)
let assetImageGenerator = AVAssetImageGenerator(asset: movieAsset)
assetImageGenerator.appliesPreferredTrackTransform = true
var thumbnail: UIImage?
do {
let cgImage = try assetImageGenerator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1000), actualTime: nil)
thumbnail = UIImage(cgImage: cgImage)
} catch {
print(error)
}
return thumbnail
}
如果您需要整个视频的缩略图数组,请使用AVAssetImageGenerator类的以下 API
func generateCGImagesAsynchronously(forTimes requestedTimes: [NSValue],
completionHandler handler: @escaping AVAssetImageGeneratorCompletionHandler)
对于所需的缩略图图像分辨率设置以下属性
assetImageGenerator.maximumSize
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.