iOS视频录制、压缩导出、取帧

  // 7.0 AVAuthorizationStatus authStatus = [AVCaptureDeviceauthorizationStatusForMediaType:AVMediaTypeVideo]; if (authStatus == AVAuthorizationStatusRestricted     || authStatus == AVAuthorizationStatusDenied) {   NSLog(@"摄像头已被禁用，您可在设置应用程序中进行开启");   return; }   if ([UIImagePickerControllerisSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {   UIImagePickerController *picker = [[UIImagePickerController alloc]init];   picker.delegate = self;   picker.allowsEditing = YES;   picker.sourceType = UIImagePickerControllerSourceTypeCamera;   picker.videoQuality = UIImagePickerControllerQualityType640x480; //录像质量   picker.videoMaximumDuration = 5 * 60.0f; // 限制视频录制最多不超过5分钟   picker.mediaTypes = @[(NSString *)kUTTypeMovie];   [selfpresentViewController:pickeranimated:YEScompletion:NULL];   self.shouldAsync = YES; } else {   NSLog(@"手机不支持摄像"); }   

  AVAuthorizationStatus authStatus = [AVCaptureDeviceauthorizationStatusForMediaType:AVMediaTypeVideo]; if (authStatus == AVAuthorizationStatusRestricted     || authStatus == AVAuthorizationStatusDenied) {   NSLog(@"摄像头已被禁用，您可在设置应用程序中进行开启");   return; }   if ([UIImagePickerControllerisSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum]) {   UIImagePickerController *picker = [[UIImagePickerController alloc]init];   picker.delegate = self;   picker.allowsEditing = YES;   picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;   picker.mediaTypes = @[(NSString *)kUTTypeMovie];   [selfpresentViewController:pickeranimated:YEScompletion:NULL];   self.shouldAsync = NO; } else {   NSLog(@"手机不支持摄像"); }   

  NSURL *videoURL = [infoobjectForKey:UIImagePickerControllerMediaURL]; ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init]; dispatch_async(dispatch_get_global_queue(0, 0), ^{   // 判断相册是否兼容视频，兼容才能保存到相册   if ([libraryvideoAtPathIsCompatibleWithSavedPhotosAlbum:videoURL]) {     [librarywriteVideoAtPathToSavedPhotosAlbum:videoURLcompletionBlock:^(NSURL *assetURL, NSError *error) {       dispatch_async(dispatch_get_main_queue(), ^{         // 写入相册         if (error == nil) {             NSLog(@"写入相册成功");         } else {           NSLog(@"写入相册失败");         }       }     }];   } });   

  // Get the video's center frame as video poster image - (UIImage *)frameImageFromVideoURL:(NSURL *)videoURL {   // result   UIImage *image = nil;      // AVAssetImageGenerator   AVAsset *asset = [AVAssetassetWithURL:videoURL];   AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];   imageGenerator.appliesPreferredTrackTransform = YES;      // calculate the midpoint time of video   Float64 duration = CMTimeGetSeconds([assetduration]);   // 取某个帧的时间，参数一表示哪个时间（秒），参数二表示每秒多少帧   // 通常来说，600是一个常用的公共参数，苹果有说明:   // 24 frames per second (fps) for film, 30 fps for NTSC (used for TV in North America and   // Japan), and 25 fps for PAL (used for TV in Europe).   // Using a timescale of 600, you can exactly represent any number of frames in these systems   CMTime midpoint = CMTimeMakeWithSeconds(duration / 2.0, 600);      // get the image from   NSError *error = nil;   CMTime actualTime;   // Returns a CFRetained CGImageRef for an asset at or near the specified time.   // So we should mannully release it   CGImageRef centerFrameImage = [imageGeneratorcopyCGImageAtTime:midpoint                                                        actualTime:&actualTime                                                             error:&error];      if (centerFrameImage != NULL) {     image = [[UIImage alloc]initWithCGImage:centerFrameImage];     // Release the CFRetained image     CGImageRelease(centerFrameImage);   }      return image; }   

  // 异步获取帧图片，可以一次获取多帧图片 - (void)centerFrameImageWithVideoURL:(NSURL *)videoURLcompletion:(void (^)(UIImage *image))completion {   // AVAssetImageGenerator   AVAsset *asset = [AVAssetassetWithURL:videoURL];   AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];   imageGenerator.appliesPreferredTrackTransform = YES;      // calculate the midpoint time of video   Float64 duration = CMTimeGetSeconds([assetduration]);   // 取某个帧的时间，参数一表示哪个时间（秒），参数二表示每秒多少帧   // 通常来说，600是一个常用的公共参数，苹果有说明:   // 24 frames per second (fps) for film, 30 fps for NTSC (used for TV in North America and   // Japan), and 25 fps for PAL (used for TV in Europe).   // Using a timescale of 600, you can exactly represent any number of frames in these systems   CMTime midpoint = CMTimeMakeWithSeconds(duration / 2.0, 600);      // 异步获取多帧图片   NSValue *midTime = [NSValuevalueWithCMTime:midpoint];   [imageGeneratorgenerateCGImagesAsynchronouslyForTimes:@[midTime]completionHandler:^(CMTime requestedTime, CGImageRef  _Nullableimage, CMTime actualTime, AVAssetImageGeneratorResult result, NSError * _Nullableerror) {     if (result == AVAssetImageGeneratorSucceeded && image != NULL) {       UIImage *centerFrameImage = [[UIImage alloc]initWithCGImage:image];       dispatch_async(dispatch_get_main_queue(), ^{         if (completion) {           completion(centerFrameImage);         }       });     } else {       dispatch_async(dispatch_get_main_queue(), ^{         if (completion) {           completion(nil);         }       });     }   }]; }   

  - (void)compressVideoWithVideoURL:(NSURL *)videoURL                         savedName:(NSString *)savedName                        completion:(void (^)(NSString *savedPath))completion {   // Accessing video by URL   AVURLAsset *videoAsset = [[AVURLAsset alloc]initWithURL:videoURLoptions:nil];      // Find compatible presets by video asset.   NSArray *presets = [AVAssetExportSessionexportPresetsCompatibleWithAsset:videoAsset];      // Begin to compress video   // Now we just compress to low resolution if it supports   // If you need to upload to the server, but server does't support to upload by streaming,   // You can compress the resolution to lower. Or you can support more higher resolution.   if ([presetscontainsObject:AVAssetExportPreset640x480]) {     AVAssetExportSession *session = [[AVAssetExportSession alloc]initWithAsset:videoAsset  presetName:AVAssetExportPreset640x480];          NSString *doc = [NSHomeDirectory()stringByAppendingPathComponent:@"Documents"];     NSString *folder = [docstringByAppendingPathComponent:@"HYBVideos"];     BOOL isDir = NO;     BOOL isExist = [[NSFileManager defaultManager]fileExistsAtPath:folderisDirectory:&isDir];     if (!isExist || (isExist && !isDir)) {       NSError *error = nil;       [[NSFileManager defaultManager]createDirectoryAtPath:folder                                 withIntermediateDirectories:YES                                                  attributes:nil                                                       error:&error];       if (error == nil) {         NSLog(@"目录创建成功");       } else {         NSLog(@"目录创建失败");       }     }          NSString *outPutPath = [folderstringByAppendingPathComponent:savedName];     session.outputURL = [NSURLfileURLWithPath:outPutPath];          // Optimize for network use.     session.shouldOptimizeForNetworkUse = true;          NSArray *supportedTypeArray = session.supportedFileTypes;     if ([supportedTypeArraycontainsObject:AVFileTypeMPEG4]) {       session.outputFileType = AVFileTypeMPEG4;     } else if (supportedTypeArray.count == 0) {       NSLog(@"No supported file types");       return;     } else {       session.outputFileType = [supportedTypeArrayobjectAtIndex:0];     }          // Begin to export video to the output path asynchronously.     [sessionexportAsynchronouslyWithCompletionHandler:^{       if ([sessionstatus] == AVAssetExportSessionStatusCompleted) {         dispatch_async(dispatch_get_main_queue(), ^{           if (completion) {             completion([session.outputURLpath]);           }         });       } else {         dispatch_async(dispatch_get_main_queue(), ^{           if (completion) {             completion(nil);           }         });       }     }];   } }   

  [pickerdismissViewControllerAnimated:YEScompletion:^{     // for fixing iOS 8.0 problem that frame changed when open camera to record video.     self.tabBarController.view.frame  = [[UIScreen mainScreen]bounds];     [self.tabBarController.viewlayoutIfNeeded]; }];