获取视频元数据，如何检测视频是从前置摄像头还是后置摄像头拍摄的天气

如何解决获取视频元数据，如何检测视频是从前置摄像头还是后置摄像头拍摄的天气

我想知道视频是从前置摄像头还是后置摄像头拍摄的。由于 info 返回 nil。

let asset: PHAsset! 
 let manager = PHImageManager.default()
    if asset.mediaType == .video {
      let options: PHVideoRequestOptions = PHVideoRequestOptions()
      options.version = .original
      options.isNetworkAccessAllowed = true
      manager.requestAVAsset(forVideo: asset,options: options) { (asset,audiomix,info) in
}

解决方法

令人惊讶的是，您可以将 PHImageManager.requestImageDataAndOrientation 用于 VIDEO 资产。

Xcode 12.5
iPhone SE 2020 (iOS 14.6)

观察

let imageManager = PHImageManager.default()
imageManager.requestImageDataAndOrientation(for: videoPHAsset,options: nil) { (data,string,orientation,info) in
    if let data = data,let ciImage = CIImage(data: data) {
        print(ciImage.properties)
    }
}

将 ciImage.properties 序列化为 JSON 后，得到以下结果。

1.视频（后置摄像头）

{"ColorModel":"RGB","PixelHeight":1920,"{Exif}":{"ColorSpace":1,"PixelXDimension":1080,"ExifVersion":[2,2,1],"FlashPixVersion":[1,0],"PixelYDimension":1920,"SceneCaptureType":0,"ComponentsConfiguration":[1,3,0]},"ProfileName":"HDTV","DPIHeight":72,"PixelWidth":1080,"{TIFF}":{"YResolution":72,"ResolutionUnit":2,"XResolution":72},"{JFIF}":{"DensityUnit":0,"YDensity":72,"JFIFVersion":[1,"XDensity":72},"Depth":8,"DPIWidth":72}

2.视频（前置摄像头）

{"Depth":8,"PixelHeight":1334,"ProfileName":"sRGB IEC61966-2.1","PixelWidth":750,"ColorModel":"RGB","DPIWidth":72,"PixelXDimension":750,"PixelYDimension":1334,0]}}

3.截图

{"ColorModel":"RGB","{Exif}":{"PixelXDimension":750,"DateTimeOriginal":"2021:01:21 14:25:56","UserComment":"Screenshot"},"{PNG}":{"InterlaceType":0},"HasAlpha":true,"Depth":16,"{TIFF}":{"Orientation":1},"ProfileName":"Display P3","Orientation":1}

4.照片（有大量信息和 JSON 序列化崩溃，所以我只提取了“{Exif}”部分）

{"ExifVersion":[2,"Flash":24,"LensModel":"iPhone SE (2nd generation) back camera 3.99mm f\\/1.8","OffsetTimeDigitized":"+05:30","SubsecTimeOriginal":"630","LensSpecification":[3.990000009536743,3.990000009536743,1.7999999523162842,1.7999999523162842],"ExposureMode":0,"CompositeImage":2,"LensMake":"Apple","FNumber":1.8,"OffsetTimeOriginal":"+05:30","PixelYDimension":3024,"ApertureValue":1.6959938128383605,"ExposureBiasValue":0,"MeteringMode":5,"ISOSpeedRatings":[400],"ShutterSpeedValue":4.6443251405083465,"FocalLength":3.99,"DateTimeOriginal":"2021:01:21 20:47:05","SceneType":1,"ColorSpace":65535,"SubjectArea":[2013,1511,2217,1330],"PixelXDimension":4032,"FocalLenIn35mmFilm":28,"SubsecTimeDigitized":"630","OffsetTime":"+05:30","SensingMethod":2,"BrightnessValue":0.06030004492448258,"DateTimeDigitized":"2021:01:21 20:47:05","WhiteBalance":0,"ExposureTime":0.04,"ExposureProgram":2}

视频有"ExifVersion":[2,1]，而照片有"ExifVersion":[2,1]。视频的 exif 根本不提供有关相机的任何有用信息 - 而照片的 exif 提供。所有视频和照片都是在同一部手机上拍摄的。

在这一点上，如果这些信息甚至被编码到视频帧中，仍然一无所知。