自定义相机&GPUImage滤镜录像

业务需求照着微信小视频做，后来发现挺有意思的就研究了一下，主要是一些关键性代码和一些坑的心得体会，具体AVFoundation的使用和UI搭建具体看demo就好。目前性能方面有些粗糙，交流学习使用，后期会将相关优化代码合并进来。
相关功能：
视频循环播放，视频压缩（80%压缩率）;
录像时摄像头切换的I/O处理;
GPUimage的使用心得与相关注意事项(图像旋转、画面闪烁)

1、微信小视频录制（半屏幕）

视频压缩：6秒原版视频10M上下，压缩后1.5M上下,具体大小跟像素和拍摄内容有关。
视频录制压缩具体看demo代码，别的也没什么难度。
这里放个进度条的伸缩动画。

    CABasicAnimation *scaleXAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale.x"];
    scaleXAnimation.duration = MAXDURATION;
    scaleXAnimation.fromValue = @(1.f);
    scaleXAnimation.toValue = @(0.f);
    [self.processView.layer addAnimation:scaleXAnimation forKey:@"scaleXAnimation"];

2、微信小视频录制拍照 （全屏）录制拍摄后预览功能

长按录像，点击拍照，预览确认选择

[前后摄像头切换]

- (void)swapFrontAndBackCameras {
    NSArray *inputs =self.session.inputs;
    for (AVCaptureDeviceInput *input in inputs ) {
        AVCaptureDevice *device = input.device;
        if ( [device hasMediaType:AVMediaTypeVideo] ) {
            AVCaptureDevicePosition position = device.position;
            if (position ==AVCaptureDevicePositionFront)
                self.captureDevice = [self cameraWithPosition:AVCaptureDevicePositionBack];
            else
                self.captureDevice = [self cameraWithPosition:AVCaptureDevicePositionFront];
            
                        self.videoDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:self.captureDevice error:nil];
            
                        [self.session beginConfiguration];
                        [self.session removeInput:input];
                        [self.session addInput:self.videoDeviceInput];
                        [self.session commitConfiguration];
            break;
        }
    }
}

这个只是达到了切后前后摄像头的效果，但是实际录像中切换摄像头这样会导致捕捉不到数据，所以在切换的时候需要重新配置 AVCaptureDevice和AVCaptureDeviceInput，目前处理是切换过后重新配置了session。

- (void)swapFrontAndBackCameras {
    NSArray *inputs =self.session.inputs;
    for (AVCaptureDeviceInput *input in inputs ) {
        AVCaptureDevice *device = input.device;
        if ( [device hasMediaType:AVMediaTypeVideo] ) {
            AVCaptureDevicePosition position = device.position;
            if (position ==AVCaptureDevicePositionFront)
                [self configurationSession];
            else
                [self configurationSessionFront];
            break;
        }
    }
}

[手动点击对焦]

尝试了很多对焦方式，发现这种对焦效果最好。
点击手势添加到preview上，根据点击的坐标进行计算转换point

- (void)tapPreview:(UITapGestureRecognizer *)tap {
    NSLog(@"%@", NSStringFromCGPoint([tap locationInView:self]));
    CGPoint point = [tap locationInView:self];
    [self showFouceView:point];
    CGPoint focusPoint = CGPointMake(point.x/self.width, point.y/self.height);
    [self.recorder setFocusPoint:focusPoint];
 }

- (void)setFocusPoint:(CGPoint)point {
    if (self.captureDevice.isFocusPointOfInterestSupported) {
        NSError *error = nil;
        [self.captureDevice lockForConfiguration:&error];
        /*****必须先设定聚焦位置，在设定聚焦方式******/
        //聚焦点的位置
        if ([self.captureDevice isFocusPointOfInterestSupported]) {
            [self.captureDevice setFocusPointOfInterest:point];
        }
        
        // 聚焦模式
        if ([self.captureDevice isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
            [self.captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
        }else{
            NSLog(@"聚焦模式修改失败");
        }
        
        //曝光点的位置
        if ([self.captureDevice isExposurePointOfInterestSupported]) {
            [self.captureDevice setExposurePointOfInterest:point];
        }
        
        //曝光模式
        if ([self.captureDevice isExposureModeSupported:AVCaptureExposureModeAutoExpose]) {
            [self.captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
        }else{
            NSLog(@"曝光模式修改失败");
        }
        [self.captureDevice unlockForConfiguration];
    }
}

单机拍照处理，获取AVCaptureStillImageOutput类中的 capture方法即可

 [self.recorder.imageDataOutput captureStillImageAsynchronouslyFromConnection:conntion
                                                      completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
                                                          if (imageDataSampleBuffer == nil) {
                                                              return;                                                      }
                                                          NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                                                          UIImage *img = [UIImage imageWithData:imageData];
                                                          [weakSelf previewPhoto:img];
                                                      }];

[录制 &拍摄完的 录像预览]

这里是在写了一个vc中WXVideoPreviewViewController，方便后期做滤镜处理等，拍摄完成后将view添加在录制view的上层，进行本地视频的循环播放。循环播放结束时会出现闪屏的情况，所以这里会将视频中的第一帧取出进行默认展示。如有好的方法留言告知我哈。

取本地视频第一帧画面

- (UIImage*) getVideoPreViewImage {
    AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:[NSURL URLWithString:self.url] options:nil];
    AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    
    gen.appliesPreferredTrackTransform = YES;
    CMTime time = CMTimeMakeWithSeconds(0.0, 600);
    NSError *error = nil;
    CMTime actualTime;
    CGImageRef image = [gen copyCGImageAtTime:time actualTime:&actualTime error:&error];
    UIImage *img = [[UIImage alloc] initWithCGImage:image];
    CGImageRelease(image);
    return img;
}

本地视频播放由AVPlayerItem、AVPlayer、AVPlaerLayer组成，所以封住了一个VideoPlayerView方便使用，其中_playerLayer.videoGravity这个属性需要注意到

- (instancetype)initWithFrame:(CGRect)frame videoUrl:(NSString *)url {
    if (self = [super initWithFrame:frame]) {
        _playItem = [AVPlayerItem playerItemWithURL:[self urlValidation:url]];
        _player = [[AVPlayer alloc] initWithPlayerItem:_playItem];
        _playerLayer = [AVPlayerLayer playerLayerWithPlayer:_player];
        _playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill; // 不写这句是不会全屏的！
        _playerLayer.frame = self.bounds;
        [self.layer addSublayer:_playerLayer];
        
        if (kSYSTEM_VERSION_iOS10Later) _player.automaticallyWaitsToMinimizeStalling = NO;
        [self noticeAndKVO];
    }
    return self;
}

视频重复播放，只需要在AVPlayerItemDidPlayToEndTimeNotification监听方法中，将timer重制即可

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(playerDidFinished:)
                                                 name:AVPlayerItemDidPlayToEndTimeNotification
                                               object:nil];

- (void)playerDidFinished:(NSNotification*)noti {
    [_player pause];
    [self cyclePlayVideo];
}

- (void)cyclePlayVideo {
    [_player seekToTime:kCMTimeZero];
    [_player play];
}

3、GPUImage 视频录制与拍照功能

[实时添加滤镜与前后镜头切换录制]

这里有个不解 _filterView.fillMode 中写 kGPUImageFillModePreserveAspectRatioAndFill有问题,不太懂什么鬼，所以这里用2表示。

94C370D1-E565-49A2-8AA4-A975CFEE3CAB.png

camer初始化这里注意，如果出现添加滤镜闪屏的情况，尝试[self.camera removeAllTargets] 清除targets，并查看 addTarget相关代码顺序。

- (void)captureAndRecording {
    [self addSubview:self.filterView];
    
    [self.camera addTarget:self.filterView];
    [self.camera startCameraCapture];
    self.camera.audioEncodingTarget = self.writer;
}

- (GPUImageView *)filterView {
    if (!_filterView) {
        _filterView = [[GPUImageView alloc] initWithFrame:self.bounds];
        _filterView.fillMode = 2;//kGPUImageFillModePreserveAspectRatioAndFill
    }
    return _filterView;
}

- (GPUImageStillCamera *)camera {
    if (!_camera) {
        self.camera = [[GPUImageStillCamera alloc] initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionBack];
        self.camera.outputImageOrientation = UIInterfaceOrientationPortrait;
        self.camera.horizontallyMirrorFrontFacingCamera = YES; // 前置摄像头需要 镜像反转
        self.camera.horizontallyMirrorRearFacingCamera = NO; // 后置摄像头不需要 镜像反转 （default：NO）
        [self.camera addAudioInputsAndOutputs]; //该句可防止允许声音通过的情况下，避免录制第一帧黑屏闪屏
    }
    return _camera;
}

滤镜切换, 由于GPUImage 无滤镜的时候不支持录像和拍照，所以正常模式不做处理。没有滤镜的时候如何进行录像和拍照，如有老司机知道望告知一下啊，交流学习。
这里GPUImageBeautifyFilter 美颜处理来自guikz ，感谢github开源精神。

- (void)filter:(UIButton *)btn {
    FaceCameraFilterEnum filterEnum = btn.tag;
    [self.camera removeAllTargets];
    switch (filterEnum) {
        case FaceCameraFilterNone:{
            btn.tag = 1;
            [self.camera addTarget:_filterView];
            _tempFilter = nil;
            [_beautifyBtn setTitle:@"无" forState:UIControlStateNormal];
        }
            break;
        case FaceCameraFilterBeautify:{
            btn.tag = 2;
            // MARK: 添加 美颜滤镜
            _beautifyFilter = [[GPUImageBeautifyFilter alloc] init];
            [self.camera addTarget:_beautifyFilter];
            [_beautifyFilter addTarget:_filterView];
            [_beautifyFilter addTarget:self.writer];
            _tempFilter = _beautifyFilter;
            [_beautifyBtn setTitle:@"美颜" forState:UIControlStateNormal];
        }
            break;
        case FaceCameraFilterSketch:{
            btn.tag = 0;
            GPUImageSketchFilter *filter = [[GPUImageSketchFilter alloc] init];
            [self.camera addTarget:filter];
            [filter addTarget:_filterView];
            [filter addTarget:self.writer];
            _tempFilter = filter;
            [_beautifyBtn setTitle:@"黑白" forState:UIControlStateNormal];
        }
            break;
        default:
            break;
    }
}

拍照存储这里有个坑,如果使用 writeImageDataToSavedPhotosAlbum 这个方法进行照片存储，图片会旋转90度，所以，这里使用 UIImageWriteToSavedPhotosAlbum进行图片写入到相册。

- (void)writerCurrentFrameToLibrary {
    _savingImg = YES;
    kWeakSelf(self)

    if (_tempFilter) {
        #warning 这是第二个坑，用这种方式保存照片到相册正常，官方demo种的相片保存会90度旋转
        //            ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
        //            [library writeImageDataToSavedPhotosAlbum:processedJPEG metadata:self.camera.currentCaptureMetadata completionBlock:^(NSURL *assetURL, NSError *error2) {
        //            }];
        [self.camera capturePhotoAsJPEGProcessedUpToFilter:_tempFilter withCompletionHandler:^(NSData *processedJPEG, NSError *error){
            UIImage *img = [UIImage imageWithData:processedJPEG];
            [weakSelf saveImageWriteToPhotosAlbum:img];
        }];
    }else {
         [self showAlterViewTitle:@"失败" message:@"没有滤镜不能进行拍照"];
    }
}

- (void)saveImageWriteToPhotosAlbum:(UIImage *)img {
    ALAuthorizationStatus author = [ALAssetsLibrary authorizationStatus];
    if (author == ALAuthorizationStatusRestricted || author == ALAuthorizationStatusDenied){
        //无权限
        return ;
    }
    if (img) {
        UIImageWriteToSavedPhotosAlbum(img, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
    }else {
         [self showAlterViewTitle:@"失败" message:@"照片保存失败"];
    }
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
    if (!error) {
        [self showAlterViewTitle:@"成功" message:@"照片保存成功"];
    }else {
        [self showAlterViewTitle:@"失败" message:@"照片保存失败"];
    }
}

4、本地&在线小视频播放（略粗糙）

没什么难度，感觉稍微有用点代码是视频下载这段

- (void)downloadVideo {
    NSString *domainUrl = self.videoUrlString;
    NSURLRequest *request =[NSURLRequest requestWithURL:[NSURL URLWithString:domainUrl] cachePolicy:1 timeoutInterval:15.0f];
    
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSMutableString * path = [[NSMutableString alloc]initWithString:documentsDirectory];
        NSString *timeString = [NSString stringWithFormat:@"%.0f", [[NSDate dateWithTimeIntervalSinceNow:0] timeIntervalSince1970]];
        [path appendString:[NSString stringWithFormat:@"/%@.mov", timeString]];
        
        NSLog(@"path == %@", path);
        
        if ([data writeToFile:path atomically:YES])
        {
            NSLog(@"mov写入成功");
            UIImageWriteToSavedPhotosAlbum([UIImage imageWithContentsOfFile:path], nil, nil, NULL);
            BOOL compatible = UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(path);
            if (compatible)
            {
                UISaveVideoAtPathToSavedPhotosAlbum(path, self, nil, NULL);
                NSLog(@"视频保存成功");
            }
            else
            {
                NSLog(@"视频保存失败");
            }
        }
        else
        {
            NSLog(@"mov写入失败");
        }
    }];
}

截图

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第一次写，比较仓促，后期想到什么了再补，一起交流学习。

Demo:
https://github.com/MarkBuster/MBSmartVideo