這裡介紹使用GPUImage為本地視訊新增濾鏡，下面會對GPUImage使用過程進行介紹並說明一些需要注意的東西：

工程中需要的檔案可以到文章最後連結下載

首先把gpuimage.a和放置GPUImage標頭檔案的資料夾usr新增到專案中

然後需要在info.plist檔案中新增鍵值獲取照片庫訪問許可權：
NSPhotoLibraryUsageDescription
是否允許此App訪問你的媒體資料庫？

然後匯入 AssetsLibrary框架
這裡是獲取了系統照片庫第一個視訊檔案，所以執行的時候記得隨便錄製一個視訊檔案在系統照片庫

獲取GPUImage標頭檔案的引用
import GPUImage.h

下面介紹主要使用到的內容

GPUImageMovie 接收需要新增濾鏡的視訊
GPUImageView 預覽視訊效果
GPUImageOutput 視訊輸入輸出配置，這裡承載濾鏡
GPUImageMovieWriter 新增濾鏡及輸出視訊

 // 
 //  ViewController.m 
 //  VideoFilterText 
 // 
 // 


 #import "ViewController.h" 


 #import "GPUImage.h" 


 #import <AssetsLibrary/AssetsLibrary.h> 


 #define WIDTH [UIScreen mainScreen].bounds.size.width 
 

 #define HEIGHT [UIScreen mainScreen].bounds.size.height 


 #define WINDOW [[UIApplication sharedApplication] keyWindow] 


 @interface ViewController () 


 @property (nonatomic,strong)GPUImageMovie * gpuMovie;//接管視訊資料 


 @property (nonatomic,strong)GPUImageView * gpuView;//預覽視訊內容 


 @property (nonatomic
 
,strong)GPUImageOutput<GPUImageInput> * pixellateFilter;//視訊濾鏡 


 @property (nonatomic,strong)GPUImageMovieWriter * movieWriter;//視訊處理輸出 


 @property (nonatomic,strong)UIScrollView * EditView;//濾鏡選擇檢視 


 @property (nonatomic,strong)NSArray * GPUImgArr;//存放濾鏡陣列 


 @property (nonatomic,copy)NSURL * filePath;//照片庫第一個視訊路徑 
 @property (nonatomic,copy)NSString * fileSavePath;//視訊合成後儲存路徑  

 @property (nonatomic,strong)NSMutableDictionary * dic;//存放上個濾鏡filter 


 @property (nonatomic,assign)NSTimer * timer;//設定計時器，因為重複合成同一個濾鏡時間會很長超時後重新建立 
 @property (nonatomic,assign)int timeNum;//記時時間 


 @property (nonatomic,strong)UIView * hudView;//載入框 


 @end 


 @implementation ViewController 


 - (void)viewDidLoad { 

   [super viewDidLoad]; 

     self.view.backgroundColor = [UIColor whiteColor]; 

    _dic = [[NSMutableDictionary alloc]initWithDictionary:@{@"filter":@""}]; 

   [self getVideoUrl];//獲取系統照片庫第一個視訊檔案 

   // Do any additional setup after loading the view, typically from a nib. 
 } 


 -(void)getVideoUrl{ 
     NSString *tipTextWhenNoPhotosAuthorization; // 提示語 
     // 獲取當前應用對照片的訪問授權狀態 
     ALAuthorizationStatus authorizationStatus = [ALAssetsLibrary authorizationStatus]; 
     // 如果沒有獲取訪問授權，或者訪問授權狀態已經被明確禁止，則顯示提示語，引導使用者開啟授權 
     if (authorizationStatus == ALAuthorizationStatusRestricted || authorizationStatus == ALAuthorizationStatusDenied) { 
         NSDictionary *mainInfoDictionary = [[NSBundle mainBundle] infoDictionary]; 
         NSString *appName = [mainInfoDictionary objectForKey:@"CFBundleDisplayName"]; 
         tipTextWhenNoPhotosAuthorization = [NSString stringWithFormat:@"請在裝置的\"設定-隱私-照片\"選項中，允許%@訪問你的手機相簿", appName]; 
         // 展示提示語 
     } 

    ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init]; 

    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) { 
         if (group) { 

             [group setAssetsFilter:[ALAssetsFilter allVideos]]; 
             if (group.numberOfAssets > 0) { 

                [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) { 

                    static int i = 1; 

                    if (i == 1) { 
                         i++; 
                         NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init]; 
                         [dateFormatter setTimeZone:[NSTimeZone localTimeZone]]; 
                         [dateFormatter setDateFormat:@"yyyyMMddHHmmss"]; //注意時間的格式：MM表示月份，mm表示分鐘，HH用24小時制，小hh是12小時制。 
                         NSString* dateString = [dateFormatter stringFromDate:[result valueForProperty:ALAssetPropertyDate]]; 

                         if (dateString) { 
                             _filePath = result.defaultRepresentation.url; 
                             [self createUI]; 
                        } 
                    } 
                 }]; 
             } 
         } 

    } failureBlock:^(NSError *error) { 
         NSLog(@"Asset group not found!\n"); 
     }]; 

 } 


 -(void)createUI{ 

    _gpuView = [[GPUImageView alloc]initWithFrame:CGRectMake(0, 0, WIDTH, HEIGHT-200)]; 
     //設定展示頁面的旋轉 
 //    [_gpuView setInputRotation:kGPUImageRotateRight atIndex:0]; 

    [self.view addSubview:_gpuView]; 

   NSLog(@"filePath = %@",_filePath); 

    _gpuMovie = [[GPUImageMovie alloc]initWithURL:_filePath]; 
     _gpuMovie.shouldRepeat = YES;//迴圈 
     [_gpuMovie addTarget:_gpuView]; 
     [_gpuMovie startProcessing]; 
     [self createEditView]; 
     UIButton * composeBtn = [UIButton buttonWithType:UIButtonTypeCustom]; 
     composeBtn.frame = CGRectMake(30, HEIGHT-80, WIDTH-60, 40); 
     composeBtn.backgroundColor = [UIColor blackColor]; 
     [composeBtn setTitle:@"合成" forState:UIControlStateNormal]; 
     [composeBtn addTarget:self action:@selector(composeBtnClick:) forControlEvents:UIControlEventTouchUpInside]; 
     [self.view addSubview:composeBtn]; 
 } 

 #pragma mark ---------------------------選擇濾鏡---------------------------- 


 -(void)effectImgClick:(UIButton *)button{ 
     for (int i = 0 ; i<_GPUImgArr.count ;i++) { 
         UIButton *btn = [_EditView viewWithTag:1000+i]; 
         btn.layer.borderWidth = 0; 
         btn.userInteractionEnabled = YES; 
     } 
     button.userInteractionEnabled = NO; 
     button.layer.borderWidth = 2; 
     button.layer.borderColor = [UIColor redColor].CGColor; 

     [_gpuMovie cancelProcessing]; 
     [_gpuMovie removeAllTargets]; 
     _gpuMovie = [[GPUImageMovie alloc]initWithURL:_filePath]; 
     if (button.tag == 1000) { 
         _pixellateFilter = nil; 
         [_gpuMovie addTarget:_gpuView]; 
     }else{ 
         _pixellateFilter = (GPUImageOutput<GPUImageInput> *)[_GPUImgArr[button.tag-1000] objectForKey:@"filter"]; 
         [_gpuMovie addTarget:_pixellateFilter]; 
         [_pixellateFilter addTarget:_gpuView]; 
     } 
     [_gpuMovie startProcessing]; 
 } 


#pragma mark ----------------------------合成視訊點選事件------------------------- 
 -(void)composeBtnClick:(UIButton *)btn{ 
     NSLog(@"開始合成"); 
     if ((_pixellateFilter == nil)|| (_pixellateFilter == _dic[@"filter"] )) { 
         NSLog(@"未選擇濾鏡、或者與上個濾鏡重複。請換個濾鏡"); 

     }else{ 
         [self createHudView]; 
         _timeNum = 0; 
         _timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timeRun) userInfo:nil repeats:YES]; 
         NSURL *movieURL = [NSURL fileURLWithPath:self.fileSavePath]; 
         _movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:movieURL size:CGSizeMake(WIDTH, WIDTH*744/720-30)]; 
        [_pixellateFilter addTarget:_movieWriter]; 

        _movieWriter.shouldPassthroughAudio = YES; 

        [_gpuMovie enableSynchronizedEncodingUsingMovieWriter:_movieWriter]; 
         [_movieWriter startRecording]; 

       __weak ViewController * weakSelf = self; 

        [_movieWriter setFailureBlock:^(NSError *error) { 
             NSLog(@"合成失敗 173：error = %@",error.description); 

            dispatch_async(dispatch_get_main_queue(), ^{ 

                weakSelf.hudView.hidden = YES; 

               [weakSelf.pixellateFilter removeTarget:weakSelf.movieWriter]; 
                 [weakSelf.dic setObject:weakSelf.pixellateFilter forKey:@"filter"]; 

               [weakSelf.movieWriter finishRecording]; 

               [weakSelf.timer setFireDate:[NSDate distantFuture]]; 


             }); 
         }]; 
         [_movieWriter setCompletionBlock:^{ 
             NSLog(@"視訊合成結束: 188 "); 

            dispatch_async(dispatch_get_main_queue(), ^{ 
                 weakSelf.hudView.hidden = YES; 


                 [weakSelf.pixellateFilter removeTarget:weakSelf.movieWriter]; 
                 [weakSelf.dic setObject:weakSelf.pixellateFilter forKey:@"filter"]; 

                [weakSelf.movieWriter finishRecording]; 

               [weakSelf.timer setFireDate:[NSDate distantFuture]]; 

            }); 
      }]; 

  } 
 } 

pragma mark -----------------------計時器-------------------------- 
 -(void)timeRun{ 

     _timeNum += 1; 

     if (_timeNum >= 60) { 
         NSLog(@"視訊處理超時"); 
         [_timer invalidate]; 
         _hudView.hidden = YES; 
         [self createUI]; 

   } 
 } 

 #pragma mark -----------------------------建立載入框------------------------ 


 -(void)createHudView{ 

     if (!_hudView) { 
         _hudView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, WIDTH, HEIGHT)]; 
         _hudView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.6]; 

       UIView * huV = [[UIView alloc]initWithFrame:CGRectMake(WIDTH/2-50, HEIGHT/2-50, 100, 100)]; 
         huV.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.6]; 

        huV.layer.cornerRadius = 5; 
         huV.clipsToBounds = YES; 

        UIActivityIndicatorView * activityView = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]; 

       activityView.frame = CGRectMake(0, 0,huV.frame.size.width, huV.frame.size.height); 

        [activityView startAnimating]; 

        [huV addSubview:activityView]; 

        [_hudView addSubview:huV]; 

      [WINDOW addSubview:_hudView]; 

   }else{ 

     _hudView.hidden = NO; 

   } 

} 

 #pragma mark -----------------------------視訊存放位置------------------------ 
 -(NSString *)fileSavePath{ 

    NSFileManager* fileManager = [NSFileManager defaultManager]; 

     NSString *pathDocuments = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0]; 
     NSString *createPath = [NSString stringWithFormat:@"%@/myVidio/333.mp4", pathDocuments];//視訊存放位置 
     NSString *createPath2 = [NSString stringWithFormat:@"%@/myVidio", pathDocuments];//視訊存放資料夾 
     //判斷視訊檔案是否存在，存在刪除 
     BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:createPath]; 
     if (blHave) { 
         BOOL blDele= [fileManager removeItemAtPath:createPath error:nil]; 
         if (!blDele) { 
             [fileManager removeItemAtPath:createPath error:nil]; 
         } 
     } 
     //判斷視訊存放資料夾是否存在，不存在建立 
     BOOL blHave1=[[NSFileManager defaultManager] fileExistsAtPath:createPath2]; 
     if (!blHave1) { 
         [fileManager createDirectoryAtPath:createPath2 withIntermediateDirectories:YES attributes:nil error:nil]; 
     } 

   _fileSavePath = createPath; 

   NSLog(@"視訊輸出地址 fileSavePath = %@",_fileSavePath); 

    return _fileSavePath; 
 } 

 #pragma mark ---------------------------建立選擇濾鏡檢視---------------------------- 


 -(void)createEditView{ 

     _EditView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, HEIGHT-190, WIDTH, 100)]; 
     _EditView.showsVerticalScrollIndicator = NO; 
     AVURLAsset * myAsset = [AVURLAsset assetWithURL:_filePath]; 

    //初始化AVAssetImageGenerator 
     AVAssetImageGenerator * imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:myAsset]; 
     imageGenerator.appliesPreferredTrackTransform = YES; 

     UIImage *inputImage = [[UIImage alloc]init]; 


     // First image 
     //建立第一張預覽圖 
     CGImageRef halfWayImage = [imageGenerator copyCGImageAtTime:kCMTimeZero actualTime:nil error:nil]; 
     if (halfWayImage != NULL) { 
         inputImage = [[UIImage alloc] initWithCGImage:halfWayImage]; 
     } 

  _GPUImgArr = [self CreateGPUArr]; 

    for (int i = 0; i<_GPUImgArr.count; i++) { 

       UIButton * effectImg = [UIButton buttonWithType:UIButtonTypeCustom]; 
         effectImg.frame = CGRectMake(10+i*((WIDTH-10)/5), 10, (WIDTH-10)/5-10,  (WIDTH-10)/5-10); 
         [effectImg setImage:inputImage forState:UIControlStateNormal]; 

        if (i>0) { 

           GPUImageOutput<GPUImageInput> * disFilter = (GPUImageOutput<GPUImageInput> *)[_GPUImgArr[i] objectForKey:@"filter"]; 

             //設定要渲染的區域 
             [disFilter useNextFrameForImageCapture]; 
             //獲取資料來源 
             GPUImagePicture *stillImageSource = [[GPUImagePicture alloc]initWithImage:inputImage]; 
             //新增上濾鏡 
             [stillImageSource addTarget:disFilter]; 
             //開始渲染    
                      [stillImageSource processImage]; 
             //獲取渲染後的圖片 
             UIImage *newImage = [disFilter imageFromCurrentFramebuffer]; 

          [effectImg setImage:newImage forState:UIControlStateNormal]; 

         } 

         effectImg.layer.cornerRadius = ((WIDTH-10)/5-10)/2; 
         effectImg.layer.masksToBounds = YES; 
         effectImg.tag = 1000+i; 

         [effectImg addTarget:self action:@selector(effectImgClick:) forControlEvents:UIControlEventTouchUpInside]; 

         if (i == 0) { 
             effectImg.layer.borderWidth = 2; 
           effectImg.layer.borderColor = [UIColor redColor].CGColor; 
   } 
    UILabel * effectName = [[UILabel alloc]initWithFrame:CGRectMake(effectImg.frame.origin.x, CGRectGetMaxY(effectImg.frame)+10, effectImg.frame.size.width, 20)]; 
     effectName.textColor = [UIColor blackColor]; 
        effectName.textAlignment = NSTextAlignmentCenter; 

         effectName.font = [UIFont systemFontOfSize:12]; 

         effectName.text = _GPUImgArr[i][@"name"]; 

        [_EditView addSubview:effectImg]; 
         [_EditView addSubview:effectName]; 

        _EditView.contentSize = CGSizeMake(_GPUImgArr.count*(WIDTH-10)/5+10, _EditView.frame.size.height); 
     } 

   [self.view addSubview:_EditView]; 
 } 

pragma mark ------------------------濾鏡陣列----------------------- 

 //濾鏡檔案很多，可以自行查詢，這裡為了方便只寫了下面幾個
 -(NSArray *)CreateGPUArr{ 
     NSMutableArray * arr = [[NSMutableArray alloc]init]; 

     NSString * title0 = @"原圖"; 
     NSDictionary * dic0 = [NSDictionary dictionaryWithObjectsAndKeys:@"",@"filter",title0,@"name", nil]; 
     [arr addObject:dic0]; 


     GPUImageOutput<GPUImageInput> * Filter5 = [[GPUImageGammaFilter alloc] init]; 
     [(GPUImageGammaFilter *)Filter5 setGamma:1.5]; 
     NSString * title5 = @"伽馬線"; 
     NSDictionary * dic5 = [NSDictionary dictionaryWithObjectsAndKeys:Filter5,@"filter",title5,@"name", nil]; 
     [arr addObject:dic5]; 

     GPUImageOutput<GPUImageInput> * Filter6 = [[GPUImageColorInvertFilter alloc] init]; 
     NSString * title6 = @"反色"; 
     NSDictionary * dic6 = [NSDictionary dictionaryWithObjectsAndKeys:Filter6,@"filter",title6,@"name", nil]; 
     [arr addObject:dic6]; 

     GPUImageOutput<GPUImageInput> * Filter7 = [[GPUImageSepiaFilter alloc] init]; 
     NSString * title7 = @"褐色懷舊"; 
     NSDictionary * dic7 = [NSDictionary dictionaryWithObjectsAndKeys:Filter7,@"filter",title7,@"name", nil]; 
     [arr addObject:dic7]; 

     GPUImageOutput<GPUImageInput> * Filter8 = [[GPUImageGrayscaleFilter alloc] init]; 
     NSString * title8 = @"灰度"; 
     NSDictionary * dic8 = [NSDictionary dictionaryWithObjectsAndKeys:Filter8,@"filter",title8,@"name", nil]; 
     [arr addObject:dic8]; 

     GPUImageOutput<GPUImageInput> * Filter9 = [[GPUImageHistogramGenerator alloc] init]; 
     NSString * title9 = @"色彩直方圖？"; 
     NSDictionary * dic9 = [NSDictionary dictionaryWithObjectsAndKeys:Filter9,@"filter",title9,@"name", nil]; 
     [arr addObject:dic9]; 


     GPUImageOutput<GPUImageInput> * Filter10 = [[GPUImageRGBFilter alloc] init]; 
     NSString * title10 = @"RGB"; 
     [(GPUImageRGBFilter *)Filter10 setRed:0.8]; 
     [(GPUImageRGBFilter *)Filter10 setGreen:0.3]; 
     [(GPUImageRGBFilter *)Filter10 setBlue:0.5]; 
     NSDictionary * dic10 = [NSDictionary dictionaryWithObjectsAndKeys:Filter10,@"filter",title10,@"name", nil]; 
     [arr addObject:dic10]; 

     GPUImageOutput<GPUImageInput> * Filter11 = [[GPUImageMonochromeFilter alloc] init]; 
     [(GPUImageMonochromeFilter *)Filter11 setColorRed:0.3 green:0.5 blue:0.8]; 
     NSString * title11 = @"單色"; 
     NSDictionary * dic11 = [NSDictionary dictionaryWithObjectsAndKeys:Filter11,@"filter",title11,@"name", nil]; 
     [arr addObject:dic11]; 

     GPUImageOutput<GPUImageInput> * Filter12 = [[GPUImageBoxBlurFilter alloc] init]; 
     //    [(GPUImageMonochromeFilter *)Filter11 setColorRed:0.3 green:0.5 blue:0.8]; 
     NSString * title12 = @"單色"; 
     NSDictionary * dic12 = [NSDictionary dictionaryWithObjectsAndKeys:Filter12,@"filter",title12,@"name", nil]; 
     [arr addObject:dic12]; 

     GPUImageOutput<GPUImageInput> * Filter13 = [[GPUImageSobelEdgeDetectionFilter alloc] init]; 
     //    [(GPUImageSobelEdgeDetectionFilter *)Filter13 ]; 
     NSString * title13 = @"漫畫反色"; 
    NSDictionary * dic13 = [NSDictionary dictionaryWithObjectsAndKeys:Filter13,@"filter",title13,@"name", nil]; 
     [arr addObject:dic13]; 

     GPUImageOutput<GPUImageInput> * Filter14 = [[GPUImageXYDerivativeFilter alloc] init]; 
     //    [(GPUImageSobelEdgeDetectionFilter *)Filter13 ]; 
     NSString * title14 = @"藍綠邊緣"; 
     NSDictionary * dic14 = [NSDictionary dictionaryWithObjectsAndKeys:Filter14,@"filter",title14,@"name", nil]; 
     [arr addObject:dic14]; 


     GPUImageOutput<GPUImageInput> * Filter15 = [[GPUImageSketchFilter alloc] init]; 
     //    [(GPUImageSobelEdgeDetectionFilter *)Filter13 ]; 
     NSString * title15 = @"素描"; 
     NSDictionary * dic15 = [NSDictionary dictionaryWithObjectsAndKeys:Filter15,@"filter",title15,@"name", nil]; 
     [arr addObject:dic15]; 

     GPUImageOutput<GPUImageInput> * Filter16 = [[GPUImageSmoothToonFilter alloc] init]; 
     //    [(GPUImageSobelEdgeDetectionFilter *)Filter13 ]; 
     NSString * title16 = @"卡通"; 
     NSDictionary * dic16 = [NSDictionary dictionaryWithObjectsAndKeys:Filter16,@"filter",title16,@"name", nil]; 
     [arr addObject:dic16]; 

     GPUImageOutput<GPUImageInput> * Filter17 = [[GPUImageColorPackingFilter alloc] init]; 
     //    [(GPUImageSobelEdgeDetectionFilter *)Filter13 ]; 
     NSString * title17 = @"監控"; 
     NSDictionary * dic17 = [NSDictionary dictionaryWithObjectsAndKeys:Filter17,@"filter",title17,@"name", nil]; 
     [arr addObject:dic17]; 


     return arr; 
 } 

 @end