标签: avfoundation

我想写一个iPhone应用程序,允许你在很短的时间内连续拍摄2张照片,我想知道它是否可以实现.市场上的应用程序似乎只能从视频流中获取低分辨率的静止帧,所以我想知道快速捕获全分辨率照片是否可行.

我想从录制的视频中提取图像.我正在使用此代码但没有结果,图像没有出现.

我正在使用下面的代码来完成这项任务

AVURLAsset* asset = [AVURLAsset URLAssetWithURL:[NSURL URLWithString:videoPath] options:nil];
AVAssetImageGenerator* imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
UIImage* image = [UIImage imageWithCGImage:[imageGenerator copyCGImageAtTime:CMTimeMake(0, 1) actualTime:nil error:nil]];
[videoFrame setImage:image];

请帮助使用代码从录制的视频中提取图像

我的问题类似于上传后的iOS UIImagePickerController结果图像方向,而不是我需要修复视频方向的图像.视频也是使用imagePickerController捕获的,所以我基本上都有视频的URL.我需要将视频转换为NSData以将其上传到服务器,但在服务器上,视频方向与图像类似,具体取决于录制视频的方向.

NSURL * urlVideo;
//fix orientation here
NSData * videoDataToUpload = [NSData dataWithContentsOfURL:urlVideoFixed];

这是我到目前为止基于我从本教程得到的内容:http://www.raywenderlich.com/13418/how-to-play-record-edit-videos-in-ios但它不起作用

-(void)videoFixOrientation{
AVAsset *firstAsset = [AVAsset assetWithURL:[self urlVideoLocalLocation]];
AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];
AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration) ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];
AVMutableVideoCompositionLayerInstruction *FirstlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:firstTrack];
AVAssetTrack *FirstAssetTrack = [[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
UIImageOrientation FirstAssetOrientation_  = UIImageOrientationUp;
BOOL  isFirstAssetPortrait_  = NO;
CGAffineTransform firstTransform = FirstAssetTrack.preferredTransform;
if(firstTransform.a == 0 && firstTransform.b == 1.0 && firstTransform.c …

我正在尝试从ios设备的摄像头获取提要以在屏幕上显示，并且我不想使用ImagePickerController，因为我想对屏幕上的视图外观进行更多控制，并且希望对屏幕上的视图进行更多控制相机的光圈和采样率。

这是我在UIViewController的viewDidLoad方法中使用的代码：

//Setting up the camera
AVCaptureSession *captureSession = [[AVCaptureSession alloc] init];
//This gets the back camera, which is the default video avcapturedevice
AVCaptureDevice *camera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = nil;
AVCaptureDeviceInput *cameraInput = [AVCaptureDeviceInput deviceInputWithDevice:camera error:&error];
if (cameraInput) {
    [captureSession addInput:cameraInput];
}
else {
    UIAlertView* alert = [[UIAlertView alloc] initWithTitle:@"Camera not found" message:@"Your device must have a camera in order to use this feature" delegate:Nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];
}
AVCaptureVideoPreviewLayer *previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];
UIView* cameraView …

我想知道如何永远重播我的背景音乐,现在当应用加载音乐开始时,但当它结束时一切都很安静,我怎么能让它一直重播.

我在用AVFoundation Framework.

宣言:

var BackgroundMusic = AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("De_Hofnar_Zonnestraal", ofType: "mp3")!), error: nil)

里面viewDidLoad:

BackgroundMusic.play()

错误日志:由于未捕获的异常'NSInvalidArgumentException'而终止应用程序,原因:' * - [AVCaptureMetadataOutput setMetadataObjectTypes:] - 找不到支持的类型.使用-availableMetadataObjectTypes.'*第一次抛出调用堆栈:

这是调试器日志中的availableMetadataObjectTypes.我不明白为什么这是空的.

(lldb)po [输出availableMetadataObjectTypes] <__ NSArrayM 0x810ae990>()

这是代码NSError*错误;

session = [[AVCaptureSession alloc] init];
[session setSessionPreset:AVCaptureSessionPresetHigh];

AVCaptureDevice* device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

AVCaptureDeviceInput* deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if ([session canAddInput:deviceInput]) {
    [session addInput:deviceInput];
}

previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
[previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

CALayer *rootLayer = [[self scannerView] layer];
[rootLayer setMasksToBounds:YES];
[previewLayer setFrame:CGRectMake(self.scannerView.frame.origin.x, self.scannerView.frame.origin.y, self.scannerView.frame.size.width, self.scannerView.frame.size.height)];
[rootLayer insertSublayer:previewLayer atIndex:0];

_labelBarcode = [[UILabel alloc] initWithFrame:CGRectMake(0, 20, 300, 40)];
_labelBarcode.backgroundColor = [UIColor darkGrayColor];
_labelBarcode.textColor = [UIColor whiteColor];
[self.scannerView …

在我的应用程序，我用AVFoundation我称之为功能showCurrentAudioProgress()使用NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "showCurrentAudioProgress", userInfo: nil, repeats: true)在viewDidLoad。我想返回这种时间格式00:00:00，但是我有一个大问题。整个功能如下所示：

var musicPlayer = AVAudioPLayer()

func showCurrentAudioProgress() {
    self.totalTimeOfAudio = self.musicPlayer.duration
    self.currentTimeOfAudio = self.musicPlayer.currentTime

    let progressToShow = Float(self.currentTimeOfAudio) / Float(self.totalTimeOfAudio)
    self.audioProgress.progress = progressToShow

    var totalTime = self.musicPlayer.duration
    totalTime -= self.currentTimeOfAudio

    self.currentTimeTimer.text = "\(currentTimeOfAudio)"
    self.AudioDurationTime.text = "\(totalTime)"  
}

如何将我收到的时间转换AVAudioPlayer为00:00:00？

AVFoundation没有为我的视频添加叠加层.我不确定我做错了什么.我已经尝试使叠加层完全变白,但它没有放在视频上.当视频播放时,它必须播放AVMutableComposition Track而不是我添加的exporter.videoComposition.我对AVFoundation的经验不足以了解出了什么问题.

AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];

// 3 - Video track
AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
                                                                    preferredTrackID:kCMPersistentTrackID_Invalid];
 //    [videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,self.videoAsset.duration)
//                        ofTrack:[[self.videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
//                         atTime:kCMTimeZero error:nil];
    CMTime insertTime = kCMTimeZero;
    for(AVURLAsset *videoAsset in self.videoArray){
        [videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:insertTime error:nil];

        // Updating the insertTime for the next insert
        insertTime = CMTimeAdd(insertTime, videoAsset.duration);
    }

// 3.1 - Create AVMutableVideoCompositionInstruction
AVMutableVideoCompositionInstruction *mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainInstruction.timeRange = videoTrack.timeRange;

// 3.2 - Create an AVMutableVideoCompositionLayerInstruction for the video …

我正在开发一个AVFoundation的项目,我可以检测到面部并在图片上添加一些内容(在拍照之前).我已经实现了预览图层和图像捕获.

我的问题是,如何引入面部检测并获取面部对象的框架/位置？是否可以在预览图层上添加一些内容,以便在图片中捕获它(想想新的Snapchat过滤器)？

TIA

我目前以以下方式导出视频：

   let exporter = AVAssetExportSession.init(asset: mixComposition, presetName: AVAssetExportPreset1280x720)
   exporter?.outputURL = outputPath
   exporter?.outputFileType = AVFileType.mp4
   exporter?.shouldOptimizeForNetworkUse = true
   exporter?.videoComposition = mainCompositionInst

15秒的视频消耗约20MB的数据。与Snapchat的2MB视频相比，这个数字似乎是完全不能接受的。

我已经降低了导出和捕获会话的质量（1280x720）。

该视频在自定义相机上拍摄。UIImagePickerController未使用。

AVAssetExportSession与默认设置一起使用。

有什么办法可以减小视频尺寸？非常感谢！

编辑1： 我尝试使用此库：https : //cocoapods.org/pods/NextLevelSessionExporter

不幸的是，这会造成尺寸问题，并删除了我的音频：

// Creating exporter
    let exporter = NextLevelSessionExporter(withAsset: mixComposition)
    exporter.outputURL = outputPath
    exporter.outputFileType = AVFileType.mp4
    exporter.videoComposition = mainCompositionInst

    let compressionDict: [String: Any] = [
        AVVideoAverageBitRateKey: NSNumber(integerLiteral: 2500000),
        AVVideoProfileLevelKey: AVVideoProfileLevelH264BaselineAutoLevel as String,
        ]

        exporter.videoOutputConfiguration = [
            AVVideoCodecKey: AVVideoCodecType.h264,
            AVVideoWidthKey: NSNumber(integerLiteral: 1280),
            AVVideoHeightKey: NSNumber(integerLiteral: 720),
            AVVideoScalingModeKey: AVVideoScalingModeResizeAspectFill,
            AVVideoCompressionPropertiesKey: compressionDict
        ] …