GPUImageVideoCamera.m源码解析

const GLfloat kColorConversion601[] = {//标准清晰度颜色转换矩阵
    1.164,  1.164, 1.164,
    0.0, -0.392, 2.017,
    1.596, -0.813,   0.0,
};
const GLfloat kColorConversion709[] = {//高清颜色转换矩阵
    1.164,  1.164, 1.164,
    0.0, -0.213, 2.112,
    1.793, -0.533,   0.0,
};
const GLfloat kColorConversion601FullRange[] = {//全彩颜色转换矩阵
    1.0,    1.0,    1.0,
    0.0,    -0.343, 1.765,
    1.4,    -0.711, 0.0,
};
NSString *const kGPUImageYUVVideoRangeConversionForRGFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;
 
 uniform sampler2D luminanceTexture;
 uniform sampler2D chrominanceTexture;
 uniform mediump mat3 colorConversionMatrix;

 void main()
 {
     mediump vec3 yuv;
     lowp vec3 rgb;
     
     yuv.x = texture2D(luminanceTexture, textureCoordinate).r;
     yuv.yz = texture2D(chrominanceTexture, textureCoordinate).rg - vec2(0.5, 0.5);
     rgb = colorConversionMatrix * yuv;
     
     gl_FragColor = vec4(rgb, 1);
 }
 );
NSString *const kGPUImageYUVFullRangeConversionForLAFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;
 
 uniform sampler2D luminanceTexture;
 uniform sampler2D chrominanceTexture;
 uniform mediump mat3 colorConversionMatrix;
 
 void main()
 {
     mediump vec3 yuv;
     lowp vec3 rgb;
     
     yuv.x = texture2D(luminanceTexture, textureCoordinate).r;
     yuv.yz = texture2D(chrominanceTexture, textureCoordinate).ra - vec2(0.5, 0.5);
     rgb = colorConversionMatrix * yuv;
     
     gl_FragColor = vec4(rgb, 1);
 }
 );

NSString *const kGPUImageYUVVideoRangeConversionForLAFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;
 
 uniform sampler2D luminanceTexture;
 uniform sampler2D chrominanceTexture;
 uniform mediump mat3 colorConversionMatrix;
 
 void main()
 {
     mediump vec3 yuv;
     lowp vec3 rgb;
     
     yuv.x = texture2D(luminanceTexture, textureCoordinate).r - (16.0/255.0);
     yuv.yz = texture2D(chrominanceTexture, textureCoordinate).ra - vec2(0.5, 0.5);
     rgb = colorConversionMatrix * yuv;
     
     gl_FragColor = vec4(rgb, 1);
 }
 );
@interface GPUImageVideoCamera () 
{
    AVCaptureDeviceInput *audioInput;//音频输入
    AVCaptureAudioDataOutput *audioOutput;//音频数据输出
    NSDate *startingCaptureTime;//开始采集时间
    dispatch_queue_t cameraProcessingQueue, audioProcessingQueue;//视频处理队列、音频处理队列
    GLProgram *yuvConversionProgram;//源程序
    GLint yuvConversionPositionAttribute, yuvConversionTextureCoordinateAttribute;//顶点属性、纹理属性
    GLint yuvConversionLuminanceTextureUniform, yuvConversionChrominanceTextureUniform;//亮度常量、色度常量
    GLint yuvConversionMatrixUniform;//yuv转换矩阵
    const GLfloat *_preferredConversion;//转换模式
    BOOL isFullYUVRange;//全彩
    int imageBufferWidth, imageBufferHeight;//宽、高
    BOOL addedAudioInputsDueToEncodingTarget;//是否添加音频输入和编码对象
}
- (void)updateOrientationSendToTargets;//更新方向到目标
- (void)convertYUVToRGBOutput;//将yup数据转换为RGB输出
@end

@implementation GPUImageVideoCamera
@synthesize captureSessionPreset = _captureSessionPreset;
@synthesize captureSession = _captureSession;
@synthesize inputCamera = _inputCamera;
@synthesize runBenchmark = _runBenchmark;
@synthesize outputImageOrientation = _outputImageOrientation;
@synthesize delegate = _delegate;
@synthesize horizontallyMirrorFrontFacingCamera = _horizontallyMirrorFrontFacingCamera, horizontallyMirrorRearFacingCamera = _horizontallyMirrorRearFacingCamera;
@synthesize frameRate = _frameRate;

- (id)init;
{
    if (!(self = [self initWithSessionPreset:AVCaptureSessionPreset640x480 cameraPosition:AVCaptureDevicePositionBack]))
    {
        return nil;
    }
    return self;
}

- (id)initWithSessionPreset:(NSString *)sessionPreset cameraPosition:(AVCaptureDevicePosition)cameraPosition; 
{
    if (!(self = [super init]))
    {
        return nil;
    }
    cameraProcessingQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,0);//创建视频处理队列
    audioProcessingQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW,0);//音频处理队列
    frameRenderingSemaphore = dispatch_semaphore_create(1);//创建帧渲染信号量
    _frameRate = 0; // 帧率
    _runBenchmark = NO;
    capturePaused = NO;//是否暂停
    outputRotation = kGPUImageNoRotation;//输出旋转
    internalRotation = kGPUImageNoRotation;//输入旋转
    captureAsYUV = YES;//yuv格式采集
    _preferredConversion = kColorConversion709;//转换矩阵为高清
    _inputCamera = nil;
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) 
    {
        if ([device position] == cameraPosition)
        {
            _inputCamera = device;
        }
    }//得到摄像头
    if (!_inputCamera) {
        return nil;
    }
    _captureSession = [[AVCaptureSession alloc] init];//初始化会话层
    [_captureSession beginConfiguration];//开始采集
    NSError *error = nil;
    videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:_inputCamera error:&error];
    if ([_captureSession canAddInput:videoInput]) 
    {
        [_captureSession addInput:videoInput];
    }//视频数据输入
    videoOutput = [[AVCaptureVideoDataOutput alloc] init];//视频数据输出
    [videoOutput setAlwaysDiscardsLateVideoFrames:NO];
    if (captureAsYUV && [GPUImageContext supportsFastTextureUpload])
    {
        BOOL supportsFullYUVRange = NO;
        NSArray *supportedPixelFormats = videoOutput.availableVideoCVPixelFormatTypes;
        for (NSNumber *currentPixelFormat in supportedPixelFormats)
        {
            if ([currentPixelFormat intValue] == kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
            {
                supportsFullYUVRange = YES;
            }
        }//是否支持全彩
        
        if (supportsFullYUVRange)
        {
            [videoOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarFullRange] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];//视频数据输出配置->色素格式
            isFullYUVRange = YES;
        }
        else
        {
            [videoOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];//视频数据输出配置->色素格式
            isFullYUVRange = NO;
        }
    }
    else
    {
        [videoOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];//视频数据输出配置->色素格式
    }
    
    runSynchronouslyOnVideoProcessingQueue(^{//同步视频数据处理
        
        if (captureAsYUV)//采集格式为YUV像是你的本能，做才是你能力和水平的体现，少想多做
        {
            [GPUImageContext useImageProcessingContext];//上下文环境即绘制环境
            if (isFullYUVRange)
            {
                yuvConversionProgram = [[GPUImageContext sharedImageProcessingContext] programForVertexShaderString:kGPUImageVertexShaderString fragmentShaderString:kGPUImageYUVFullRangeConversionForLAFragmentShaderString];//openGL源程序初始化
            }
            else
            {
                yuvConversionProgram = [[GPUImageContext sharedImageProcessingContext] programForVertexShaderString:kGPUImageVertexShaderString fragmentShaderString:kGPUImageYUVVideoRangeConversionForLAFragmentShaderString];//openGL源程序初始化
            }
            
            if (!yuvConversionProgram.initialized)
            {
                [yuvConversionProgram addAttribute:@"position"];
                [yuvConversionProgram addAttribute:@"inputTextureCoordinate"];
                
                if (![yuvConversionProgram link])
                {
                    NSString *progLog = [yuvConversionProgram programLog];
                    NSLog(@"Program link log: %@", progLog);
                    NSString *fragLog = [yuvConversionProgram fragmentShaderLog];
                    NSLog(@"Fragment shader compile log: %@", fragLog);
                    NSString *vertLog = [yuvConversionProgram vertexShaderLog];
                    NSLog(@"Vertex shader compile log: %@", vertLog);
                    yuvConversionProgram = nil;
                    NSAssert(NO, @"Filter shader link failed");
                }
            }
            
            yuvConversionPositionAttribute = [yuvConversionProgram attributeIndex:@"position"];
            yuvConversionTextureCoordinateAttribute = [yuvConversionProgram attributeIndex:@"inputTextureCoordinate"];
            yuvConversionLuminanceTextureUniform = [yuvConversionProgram uniformIndex:@"luminanceTexture"];
            yuvConversionChrominanceTextureUniform = [yuvConversionProgram uniformIndex:@"chrominanceTexture"];
            yuvConversionMatrixUniform = [yuvConversionProgram uniformIndex:@"colorConversionMatrix"];
            
            [GPUImageContext setActiveShaderProgram:yuvConversionProgram];
            
            glEnableVertexAttribArray(yuvConversionPositionAttribute);
            glEnableVertexAttribArray(yuvConversionTextureCoordinateAttribute);
        }
    });
    
    [videoOutput setSampleBufferDelegate:self queue:cameraProcessingQueue];
    if ([_captureSession canAddOutput:videoOutput])
    {
        [_captureSession addOutput:videoOutput];
    }
    else
    {
        NSLog(@"Couldn't add video output");
        return nil;
    }
    
    _captureSessionPreset = sessionPreset;
    [_captureSession setSessionPreset:_captureSessionPreset];
    
    [_captureSession commitConfiguration];
    
    return self;
}

- (GPUImageFramebuffer *)framebufferForOutput;
{
    return outputFramebuffer;
}

- (void)dealloc 
{
    [self stopCameraCapture];
    [videoOutput setSampleBufferDelegate:nil queue:dispatch_get_main_queue()];
    [audioOutput setSampleBufferDelegate:nil queue:dispatch_get_main_queue()];
    [self removeInputsAndOutputs];
#if !OS_OBJECT_USE_OBJC（IOS6以上）
    if (frameRenderingSemaphore != NULL)
    {
        dispatch_release(frameRenderingSemaphore);
    }
#endif
}

- (BOOL)addAudioInputsAndOutputs//添加音频输入和输出
{
    if (audioOutput)
        return NO;
    [_captureSession beginConfiguration];
    _microphone = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
    audioInput = [AVCaptureDeviceInput deviceInputWithDevice:_microphone error:nil];
    if ([_captureSession canAddInput:audioInput])
    {
        [_captureSession addInput:audioInput];
    }
    audioOutput = [[AVCaptureAudioDataOutput alloc] init];
    
    if ([_captureSession canAddOutput:audioOutput])
    {
        [_captureSession addOutput:audioOutput];
    }
    else
    {
        NSLog(@"Couldn't add audio output");
    }
    [audioOutput setSampleBufferDelegate:self queue:audioProcessingQueue];
    
    [_captureSession commitConfiguration];
    return YES;
}

- (BOOL)removeAudioInputsAndOutputs
{
    if (!audioOutput)
        return NO;
    
    [_captureSession beginConfiguration];//通用操作要对会话层进行操作首先要开始配置
    [_captureSession removeInput:audioInput];
    [_captureSession removeOutput:audioOutput];
    audioInput = nil;
    audioOutput = nil;
    _microphone = nil;
    [_captureSession commitConfiguration];//修改完成要记得提交操作
    return YES;
}
- (void)removeInputsAndOutputs;
{
    [_captureSession beginConfiguration];
    if (videoInput) {
        [_captureSession removeInput:videoInput];
        [_captureSession removeOutput:videoOutput];
        videoInput = nil;
        videoOutput = nil;
    }
    if (_microphone != nil)
    {
        [_captureSession removeInput:audioInput];
        [_captureSession removeOutput:audioOutput];
        audioInput = nil;
        audioOutput = nil;
        _microphone = nil;
    }
    [_captureSession commitConfiguration];
}
//重写父类的添加对象方法
- (void)addTarget:(id)newTarget atTextureLocation:(NSInteger)textureLocation;
{
    [super addTarget:newTarget atTextureLocation:textureLocation];//先执行父类的方法
    [newTarget setInputRotation:outputRotation atIndex:textureLocation];//签署协议，等待执行
}
- (void)startCameraCapture;//开始采集
{
    if (![_captureSession isRunning])
    {
        startingCaptureTime = [NSDate date];
        [_captureSession startRunning];
    };
}

- (void)stopCameraCapture;//停止采集
{
    if ([_captureSession isRunning])
    {
        [_captureSession stopRunning];
    }
}

- (void)pauseCameraCapture;//暂停采集
{
    capturePaused = YES;
}

- (void)resumeCameraCapture;//恢复采集
{
    capturePaused = NO;
}
- (void)rotateCamera//转换摄像头
{
    if (self.frontFacingCameraPresent == NO)
        return;
    
    NSError *error;
    AVCaptureDeviceInput *newVideoInput;
    AVCaptureDevicePosition currentCameraPosition = [[videoInput device] position];
    
    if (currentCameraPosition == AVCaptureDevicePositionBack)
    {
        currentCameraPosition = AVCaptureDevicePositionFront;
    }
    else
    {
        currentCameraPosition = AVCaptureDevicePositionBack;
    }
    
    AVCaptureDevice *backFacingCamera = nil;
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) 
    {
        if ([device position] == currentCameraPosition)
        {
            backFacingCamera = device;
        }
    }
    newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:backFacingCamera error:&error];
    
    if (newVideoInput != nil)
    {
        [_captureSession beginConfiguration];
        
        [_captureSession removeInput:videoInput];
        if ([_captureSession canAddInput:newVideoInput])
        {
            [_captureSession addInput:newVideoInput];
            videoInput = newVideoInput;
        }
        else
        {
            [_captureSession addInput:videoInput];
        }
        //captureSession.sessionPreset = oriPreset;
        [_captureSession commitConfiguration];
    }
    
    _inputCamera = backFacingCamera;
    [self setOutputImageOrientation:_outputImageOrientation];
}

- (AVCaptureDevicePosition)cameraPosition //get Camera Position
{
    return [[videoInput device] position];
}

+ (BOOL)isBackFacingCameraPresent;
{
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    
    for (AVCaptureDevice *device in devices)
    {
        if ([device position] == AVCaptureDevicePositionBack)
            return YES;
    }
    
    return NO;
}

- (BOOL)isBackFacingCameraPresent
{
    return [GPUImageVideoCamera isBackFacingCameraPresent];
}

+ (BOOL)isFrontFacingCameraPresent;
{
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    
    for (AVCaptureDevice *device in devices)
    {
        if ([device position] == AVCaptureDevicePositionFront)
            return YES;
    }
    
    return NO;
}

- (BOOL)isFrontFacingCameraPresent
{
    return [GPUImageVideoCamera isFrontFacingCameraPresent];
}

- (void)setCaptureSessionPreset:(NSString *)captureSessionPreset;
{
    [_captureSession beginConfiguration];
    
    _captureSessionPreset = captureSessionPreset;
    [_captureSession setSessionPreset:_captureSessionPreset];
    
    [_captureSession commitConfiguration];
}

- (void)setFrameRate:(int32_t)frameRate;
{
    _frameRate = frameRate;
    
    if (_frameRate > 0)
    {
        if ([_inputCamera respondsToSelector:@selector(setActiveVideoMinFrameDuration:)] &&
            [_inputCamera respondsToSelector:@selector(setActiveVideoMaxFrameDuration:)]) {
            
            NSError *error;
            [_inputCamera lockForConfiguration:&error];
            if (error == nil) {
#if defined(__IPHONE_7_0)
                [_inputCamera setActiveVideoMinFrameDuration:CMTimeMake(1, _frameRate)];
                [_inputCamera setActiveVideoMaxFrameDuration:CMTimeMake(1, _frameRate)];
#endif
            }
            [_inputCamera unlockForConfiguration];
            
        } else {
            
            for (AVCaptureConnection *connection in videoOutput.connections)
            {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
                if ([connection respondsToSelector:@selector(setVideoMinFrameDuration:)])
                    connection.videoMinFrameDuration = CMTimeMake(1, _frameRate);
                
                if ([connection respondsToSelector:@selector(setVideoMaxFrameDuration:)])
                    connection.videoMaxFrameDuration = CMTimeMake(1, _frameRate);
#pragma clang diagnostic pop
            }
        }
        
    }
    else
    {
        if ([_inputCamera respondsToSelector:@selector(setActiveVideoMinFrameDuration:)] &&
            [_inputCamera respondsToSelector:@selector(setActiveVideoMaxFrameDuration:)]) {
            
            NSError *error;
            [_inputCamera lockForConfiguration:&error];
            if (error == nil) {
#if defined(__IPHONE_7_0)
                [_inputCamera setActiveVideoMinFrameDuration:kCMTimeInvalid];
                [_inputCamera setActiveVideoMaxFrameDuration:kCMTimeInvalid];
#endif
            }
            [_inputCamera unlockForConfiguration];
            
        } else {
            
            for (AVCaptureConnection *connection in videoOutput.connections)
            {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
                if ([connection respondsToSelector:@selector(setVideoMinFrameDuration:)])
                    connection.videoMinFrameDuration = kCMTimeInvalid; // This sets videoMinFrameDuration back to default
                
                if ([connection respondsToSelector:@selector(setVideoMaxFrameDuration:)])
                    connection.videoMaxFrameDuration = kCMTimeInvalid; // This sets videoMaxFrameDuration back to default
#pragma clang diagnostic pop
            }
        }
        
    }
}

- (int32_t)frameRate;
{
    return _frameRate;
}

- (AVCaptureConnection *)videoCaptureConnection {
    for (AVCaptureConnection *connection in [videoOutput connections] ) {
        for ( AVCaptureInputPort *port in [connection inputPorts] ) {
            if ( [[port mediaType] isEqual:AVMediaTypeVideo] ) {
                return connection;
            }
        }
    }
    
    return nil;
}

#define INITIALFRAMESTOIGNOREFORBENCHMARK 5

- (void)updateTargetsForVideoCameraUsingCacheTextureAtWidth:(int)bufferWidth height:(int)bufferHeight time:(CMTime)currentTime;//更新纹理
{
    // First, update all the framebuffers in the targets
    for (id currentTarget in targets)
    {
        if ([currentTarget enabled])
        {
            NSInteger indexOfObject = [targets indexOfObject:currentTarget];//获得纹理索引
            NSInteger textureIndexOfTarget = [[targetTextureIndices objectAtIndex:indexOfObject] integerValue];//同上
            
            if (currentTarget != self.targetToIgnoreForUpdates)
            {
                [currentTarget setInputRotation:outputRotation atIndex:textureIndexOfTarget];//签署协议等待处理 旋转模式
                [currentTarget setInputSize:CGSizeMake(bufferWidth, bufferHeight) atIndex:textureIndexOfTarget];//签署协议等待处理  输入分辨率
                
                if ([currentTarget wantsMonochromeInput] && captureAsYUV)//黑白   yuv采集
                {
                    [currentTarget setCurrentlyReceivingMonochromeInput:YES];
                    // TODO: Replace optimization for monochrome output
                    [currentTarget setInputFramebuffer:outputFramebuffer atIndex:textureIndexOfTarget];//签署协议等待处理  输入frameBuffer 里面存放的是像素信息
                }
                else
                {
                    [currentTarget setCurrentlyReceivingMonochromeInput:NO];
                    [currentTarget setInputFramebuffer:outputFramebuffer atIndex:textureIndexOfTarget];
                }
            }
            else
            {
                [currentTarget setInputRotation:outputRotation atIndex:textureIndexOfTarget];
                [currentTarget setInputFramebuffer:outputFramebuffer atIndex:textureIndexOfTarget];
            }
        }
    }
    [outputFramebuffer unlock];//解锁
    outputFramebuffer = nil;
    
    // Finally, trigger rendering as needed
    for (id currentTarget in targets)
    {
        if ([currentTarget enabled])
        {
            NSInteger indexOfObject = [targets indexOfObject:currentTarget];
            NSInteger textureIndexOfTarget = [[targetTextureIndices objectAtIndex:indexOfObject] integerValue];
            
            if (currentTarget != self.targetToIgnoreForUpdates)
            {
                [currentTarget newFrameReadyAtTime:currentTime atIndex:textureIndexOfTarget];////签署协议等待处理 纹理准备完毕
            }
        }
    }
}

- (void)processVideoSampleBuffer:(CMSampleBufferRef)sampleBuffer;//处理视频buffer
{
    if (capturePaused)
    {
        return;
    }
    
    CFAbsoluteTime startTime = CFAbsoluteTimeGetCurrent();//获得开始时间
    CVImageBufferRef cameraFrame = CMSampleBufferGetImageBuffer(sampleBuffer);//视频帧
    int bufferWidth = (int) CVPixelBufferGetWidth(cameraFrame);//视频宽
    int bufferHeight = (int) CVPixelBufferGetHeight(cameraFrame);//视频高
    CFTypeRef colorAttachments = CVBufferGetAttachment(cameraFrame, kCVImageBufferYCbCrMatrixKey, NULL);//颜色属性
    if (colorAttachments != NULL)
    {
        if(CFStringCompare(colorAttachments, kCVImageBufferYCbCrMatrix_ITU_R_601_4, 0) == kCFCompareEqualTo)
        {
            if (isFullYUVRange)
            {
                _preferredConversion = kColorConversion601FullRange;
            }
            else
            {
                _preferredConversion = kColorConversion601;
            }
        }
        else
        {
            _preferredConversion = kColorConversion709;
        }
    }
    else
    {
        if (isFullYUVRange)
        {
            _preferredConversion = kColorConversion601FullRange;
        }
        else
        {
            _preferredConversion = kColorConversion601;
        }
    }

    CMTime currentTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);//得到当前帧的时间

    [GPUImageContext useImageProcessingContext];

    if ([GPUImageContext supportsFastTextureUpload] && captureAsYUV)
    {
        CVOpenGLESTextureRef luminanceTextureRef = NULL;
        CVOpenGLESTextureRef chrominanceTextureRef = NULL;

        if (CVPixelBufferGetPlaneCount(cameraFrame) > 0) // Check for YUV planar inputs to do RGB conversion
        {
            CVPixelBufferLockBaseAddress(cameraFrame, 0);//上锁线程同步
            
            if ( (imageBufferWidth != bufferWidth) && (imageBufferHeight != bufferHeight) )
            {
                imageBufferWidth = bufferWidth;
                imageBufferHeight = bufferHeight;
            }
            
            CVReturn err;
            // Y-plane
            glActiveTexture(GL_TEXTURE4);//获得纹理4 寄存器
            if ([GPUImageContext deviceSupportsRedTextures])
            {
                err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, [[GPUImageContext sharedImageProcessingContext] coreVideoTextureCache], cameraFrame, NULL, GL_TEXTURE_2D, GL_LUMINANCE, bufferWidth, bufferHeight, GL_LUMINANCE, GL_UNSIGNED_BYTE, 0, &luminanceTextureRef);//获得两的纹理
            }
            else
            {
                err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, [[GPUImageContext sharedImageProcessingContext] coreVideoTextureCache], cameraFrame, NULL, GL_TEXTURE_2D, GL_LUMINANCE, bufferWidth, bufferHeight, GL_LUMINANCE, GL_UNSIGNED_BYTE, 0, &luminanceTextureRef);
            }
            if (err)
            {
                NSLog(@"Error at CVOpenGLESTextureCacheCreateTextureFromImage %d", err);
            }
            
            luminanceTexture = CVOpenGLESTextureGetName(luminanceTextureRef);
            glBindTexture(GL_TEXTURE_2D, luminanceTexture);
            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);//将得到的两的纹理绑定到渲染管线上
            
            // UV-plane
            glActiveTexture(GL_TEXTURE5);
            if ([GPUImageContext deviceSupportsRedTextures])
            {
                err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, [[GPUImageContext sharedImageProcessingContext] coreVideoTextureCache], cameraFrame, NULL, GL_TEXTURE_2D, GL_LUMINANCE_ALPHA, bufferWidth/2, bufferHeight/2, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, 1, &chrominanceTextureRef);
            }
            else
            {
                err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, [[GPUImageContext sharedImageProcessingContext] coreVideoTextureCache], cameraFrame, NULL, GL_TEXTURE_2D, GL_LUMINANCE_ALPHA, bufferWidth/2, bufferHeight/2, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, 1, &chrominanceTextureRef);
            }
            if (err)
            {
                NSLog(@"Error at CVOpenGLESTextureCacheCreateTextureFromImage %d", err);
            }
            
            chrominanceTexture = CVOpenGLESTextureGetName(chrominanceTextureRef);
            glBindTexture(GL_TEXTURE_2D, chrominanceTexture);
            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
            glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);//将得到的色度纹理绑定到渲染管线上 program上

            int rotatedImageBufferWidth = bufferWidth, rotatedImageBufferHeight = bufferHeight;
            
            if (GPUImageRotationSwapsWidthAndHeight(internalRotation))//转换宽、高
            {
                rotatedImageBufferWidth = bufferHeight;
                rotatedImageBufferHeight = bufferWidth;
            }
            
            [self updateTargetsForVideoCameraUsingCacheTextureAtWidth:rotatedImageBufferWidth height:rotatedImageBufferHeight time:currentTime];
            
            CVPixelBufferUnlockBaseAddress(cameraFrame, 0);
            CFRelease(luminanceTextureRef);
            CFRelease(chrominanceTextureRef);
        }
        else
        {
        }
        
        
        if (_runBenchmark)
        {
            numberOfFramesCaptured++;//采集帧数累加
            if (numberOfFramesCaptured > INITIALFRAMESTOIGNOREFORBENCHMARK)
            {
                CFAbsoluteTime currentFrameTime = (CFAbsoluteTimeGetCurrent() - startTime);//当前时间
                totalFrameTimeDuringCapture += currentFrameTime;//录制的总时间
                NSLog(@"Average frame time : %f ms", [self averageFrameDurationDuringCapture]);
                NSLog(@"Current frame time : %f ms", 1000.0 * currentFrameTime);
            }
        }
    }
    else
    {
        CVPixelBufferLockBaseAddress(cameraFrame, 0);//上锁 线程同步
        
        int bytesPerRow = (int) CVPixelBufferGetBytesPerRow(cameraFrame);//每行的数据
        outputFramebuffer = [[GPUImageContext sharedFramebufferCache] fetchFramebufferForSize:CGSizeMake(bytesPerRow / 4, bufferHeight) onlyTexture:YES];
        [outputFramebuffer activateFramebuffer];
        glBindTexture(GL_TEXTURE_2D, [outputFramebuffer texture]);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bytesPerRow / 4, bufferHeight, 0, GL_BGRA, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddress(cameraFrame));
        
        [self updateTargetsForVideoCameraUsingCacheTextureAtWidth:bytesPerRow / 4 height:bufferHeight time:currentTime];
        
        CVPixelBufferUnlockBaseAddress(cameraFrame, 0);
        
        if (_runBenchmark)
        {
            numberOfFramesCaptured++;
            if (numberOfFramesCaptured > INITIALFRAMESTOIGNOREFORBENCHMARK)
            {
                CFAbsoluteTime currentFrameTime = (CFAbsoluteTimeGetCurrent() - startTime);
                totalFrameTimeDuringCapture += currentFrameTime;
            }
        }
    }  
}

- (void)processAudioSampleBuffer:(CMSampleBufferRef)sampleBuffer;//处理音频帧
{
    [self.audioEncodingTarget processAudioBuffer:sampleBuffer]; 
}

- (void)convertYUVToRGBOutput;//颜色空间转换
{
    [GPUImageContext setActiveShaderProgram:yuvConversionProgram];

    int rotatedImageBufferWidth = imageBufferWidth, rotatedImageBufferHeight = imageBufferHeight;

    if (GPUImageRotationSwapsWidthAndHeight(internalRotation))
    {
        rotatedImageBufferWidth = imageBufferHeight;
        rotatedImageBufferHeight = imageBufferWidth;
    }

    outputFramebuffer = [[GPUImageContext sharedFramebufferCache] fetchFramebufferForSize:CGSizeMake(rotatedImageBufferWidth, rotatedImageBufferHeight) textureOptions:self.outputTextureOptions onlyTexture:NO];//输出缓存
    [outputFramebuffer activateFramebuffer];

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//清除视口
    
    static const GLfloat squareVertices[] = {
        -1.0f, -1.0f,
        1.0f, -1.0f,
        -1.0f,  1.0f,
        1.0f,  1.0f,
    };//顶点转换矩阵 
    
    glActiveTexture(GL_TEXTURE4);
    glBindTexture(GL_TEXTURE_2D, luminanceTexture);
    glUniform1i(yuvConversionLuminanceTextureUniform, 4);

    glActiveTexture(GL_TEXTURE5);
    glBindTexture(GL_TEXTURE_2D, chrominanceTexture);
    glUniform1i(yuvConversionChrominanceTextureUniform, 5);

    glUniformMatrix3fv(yuvConversionMatrixUniform, 1, GL_FALSE, _preferredConversion);

    glVertexAttribPointer(yuvConversionPositionAttribute, 2, GL_FLOAT, 0, 0, squareVertices);
    glVertexAttribPointer(yuvConversionTextureCoordinateAttribute, 2, GL_FLOAT, 0, 0, [GPUImageFilter textureCoordinatesForRotation:internalRotation]);
    
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);//绘制图源到buffer中
}
- (CGFloat)averageFrameDurationDuringCapture;
{
    return (totalFrameTimeDuringCapture / (CGFloat)(numberOfFramesCaptured - INITIALFRAMESTOIGNOREFORBENCHMARK)) * 1000.0;
}

- (void)resetBenchmarkAverage;
{
    numberOfFramesCaptured = 0;
    totalFrameTimeDuringCapture = 0.0;
}
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    if (!self.captureSession.isRunning)
    {
        return;
    }
    else if (captureOutput == audioOutput)
    {
        [self processAudioSampleBuffer:sampleBuffer];
    }
    else
    {
        if (dispatch_semaphore_wait(frameRenderingSemaphore, DISPATCH_TIME_NOW) != 0)
        {
            return;
        }
        
        CFRetain(sampleBuffer);
        runAsynchronouslyOnVideoProcessingQueue(^{
            //Feature Detection Hook.
            if (self.delegate)
            {
                [self.delegate willOutputSampleBuffer:sampleBuffer];//签协议等待处理
            }
            
            [self processVideoSampleBuffer:sampleBuffer];
            
            CFRelease(sampleBuffer);
            dispatch_semaphore_signal(frameRenderingSemaphore);
        });
    }
}
- (void)setAudioEncodingTarget:(GPUImageMovieWriter *)newValue;
{
    if (newValue) {
        /* Add audio inputs and outputs, if necessary */
        addedAudioInputsDueToEncodingTarget |= [self addAudioInputsAndOutputs];
    } 
    else if (addedAudioInputsDueToEncodingTarget) {
        /* Remove audio inputs and outputs, if they were added by previously setting the audio encoding target */
        [self removeAudioInputsAndOutputs];
        addedAudioInputsDueToEncodingTarget = NO;
    }
    
    [super setAudioEncodingTarget:newValue];
}

- (void)updateOrientationSendToTargets;
{
    runSynchronouslyOnVideoProcessingQueue(^{
        if (captureAsYUV && [GPUImageContext supportsFastTextureUpload])
        {
            outputRotation = kGPUImageNoRotation;
            if ([self cameraPosition] == AVCaptureDevicePositionBack)
            {
                if (_horizontallyMirrorRearFacingCamera)
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:internalRotation = kGPUImageRotateRightFlipVertical; break;
                        case UIInterfaceOrientationPortraitUpsideDown:internalRotation = kGPUImageRotate180; break;
                        case UIInterfaceOrientationLandscapeLeft:internalRotation = kGPUImageFlipHorizonal; break;
                        case UIInterfaceOrientationLandscapeRight:internalRotation = kGPUImageFlipVertical; break;
                        default:internalRotation = kGPUImageNoRotation;
                    }
                }
                else
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:internalRotation = kGPUImageRotateRight; break;
                        case UIInterfaceOrientationPortraitUpsideDown:internalRotation = kGPUImageRotateLeft; break;
                        case UIInterfaceOrientationLandscapeLeft:internalRotation = kGPUImageRotate180; break;
                        case UIInterfaceOrientationLandscapeRight:internalRotation = kGPUImageNoRotation; break;
                        default:internalRotation = kGPUImageNoRotation;
                    }
                }
            }
            else
            {
                if (_horizontallyMirrorFrontFacingCamera)
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:internalRotation = kGPUImageRotateRightFlipVertical; break;
                        case UIInterfaceOrientationPortraitUpsideDown:internalRotation = kGPUImageRotateRightFlipHorizontal; break;
                        case UIInterfaceOrientationLandscapeLeft:internalRotation = kGPUImageFlipHorizonal; break;
                        case UIInterfaceOrientationLandscapeRight:internalRotation = kGPUImageFlipVertical; break;
                        default:internalRotation = kGPUImageNoRotation;
                   }
                }
                else
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:internalRotation = kGPUImageRotateRight; break;
                        case UIInterfaceOrientationPortraitUpsideDown:internalRotation = kGPUImageRotateLeft; break;
                        case UIInterfaceOrientationLandscapeLeft:internalRotation = kGPUImageNoRotation; break;
                        case UIInterfaceOrientationLandscapeRight:internalRotation = kGPUImageRotate180; break;
                        default:internalRotation = kGPUImageNoRotation;
                    }
                }
            }
        }
        else
        {
            if ([self cameraPosition] == AVCaptureDevicePositionBack)
            {
                if (_horizontallyMirrorRearFacingCamera)
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:outputRotation = kGPUImageRotateRightFlipVertical; break;
                        case UIInterfaceOrientationPortraitUpsideDown:outputRotation = kGPUImageRotate180; break;
                        case UIInterfaceOrientationLandscapeLeft:outputRotation = kGPUImageFlipHorizonal; break;
                        case UIInterfaceOrientationLandscapeRight:outputRotation = kGPUImageFlipVertical; break;
                        default:outputRotation = kGPUImageNoRotation;
                    }
                }
                else
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:outputRotation = kGPUImageRotateRight; break;
                        case UIInterfaceOrientationPortraitUpsideDown:outputRotation = kGPUImageRotateLeft; break;
                        case UIInterfaceOrientationLandscapeLeft:outputRotation = kGPUImageRotate180; break;
                        case UIInterfaceOrientationLandscapeRight:outputRotation = kGPUImageNoRotation; break;
                        default:outputRotation = kGPUImageNoRotation;
                    }
                }
            }
            else
            {
                if (_horizontallyMirrorFrontFacingCamera)
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:outputRotation = kGPUImageRotateRightFlipVertical; break;
                        case UIInterfaceOrientationPortraitUpsideDown:outputRotation = kGPUImageRotateRightFlipHorizontal; break;
                        case UIInterfaceOrientationLandscapeLeft:outputRotation = kGPUImageFlipHorizonal; break;
                        case UIInterfaceOrientationLandscapeRight:outputRotation = kGPUImageFlipVertical; break;
                        default:outputRotation = kGPUImageNoRotation;
                    }
                }
                else
                {
                    switch(_outputImageOrientation)
                    {
                        case UIInterfaceOrientationPortrait:outputRotation = kGPUImageRotateRight; break;
                        case UIInterfaceOrientationPortraitUpsideDown:outputRotation = kGPUImageRotateLeft; break;
                        case UIInterfaceOrientationLandscapeLeft:outputRotation = kGPUImageNoRotation; break;
                        case UIInterfaceOrientationLandscapeRight:outputRotation = kGPUImageRotate180; break;
                        default:outputRotation = kGPUImageNoRotation;
                    }
                }
            }
        }
        
        for (id currentTarget in targets)
        {
            NSInteger indexOfObject = [targets indexOfObject:currentTarget];
            [currentTarget setInputRotation:outputRotation atIndex:[[targetTextureIndices objectAtIndex:indexOfObject] integerValue]];
        }
    });
}

- (void)setOutputImageOrientation:(UIInterfaceOrientation)newValue;
{
    _outputImageOrientation = newValue;
    [self updateOrientationSendToTargets];
}

- (void)setHorizontallyMirrorFrontFacingCamera:(BOOL)newValue
{
    _horizontallyMirrorFrontFacingCamera = newValue;
    [self updateOrientationSendToTargets];
}

- (void)setHorizontallyMirrorRearFacingCamera:(BOOL)newValue
{
    _horizontallyMirrorRearFacingCamera = newValue;
    [self updateOrientationSendToTargets];
}

@end