视频加入滤镜灵魂出窍

1.使用AVAsset对象对视频进行逐帧读取

- (void)getImageWithAsset:(AVAsset *)videoAsset{
    
    CGFloat durationSeconds = CMTimeGetSeconds(videoAsset.duration);
    AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:videoAsset];
    gen.appliesPreferredTrackTransform = YES;
    gen.requestedTimeToleranceAfter = kCMTimeZero;
    gen.requestedTimeToleranceBefore = kCMTimeZero;
    
    NSMutableArray *times = [NSMutableArray arrayWithCapacity:0];
    CGFloat totalFrames = durationSeconds * 10;
    for (int i = 0; i < totalFrames; i++) {
        CMTime timeframe = CMTimeMake(i, 10);
        NSValue *timeValue = [NSValue valueWithCMTime:timeframe];
        [times addObject:timeValue];
    }
    [gen generateCGImagesAsynchronouslyForTimes:times completionHandler:^(CMTime requestedTime, CGImageRef  _Nullable image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError * _Nullable error) {
        if (result == AVAssetImageGeneratorSucceeded) {
            UIImage *resultImage = [UIImage imageWithCGImage:image];
            dispatch_async(dispatch_get_main_queue(), ^{
                [self configTextWithImage:resultImage];
            });
        }
    }];
}

其中configTextWithImage方法是对每帧数据进行加入对应的滤镜特征，可以是灵魂出窍、缩放、灵魂出窍、抖动、闪白、毛刺、幻觉等功能等

- (void)configTextWithImage:(UIImage *)image{
    //将JPG图片转换成纹理图片
    GLuint textureID = [self createTextureWithImage:image];
    //设置纹理ID
    self.textureID = textureID;  // 将纹理 ID 保存，方便后面切换滤镜的时候重用
    
    //7.设置视口
    glViewport(0, 0, self.drawableWidth, self.drawableHeight);
    
    //8.设置顶点缓存区
    GLuint vertexBuffer;
    glGenBuffers(1, &vertexBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    GLsizeiptr bufferSizeBytes = sizeof(SenceVertex) * 4;
    glBufferData(GL_ARRAY_BUFFER, bufferSizeBytes, self.vertices, GL_STATIC_DRAW);
    
    //9.设置默认着色器
    //注意在此处更改着色器的读取文件
    [self setupShaderProgramWithName:@"SplitScreen_out"]; // 一开始选用默认的着色器
    
    //10.将顶点缓存保存，退出时才释放
    self.vertexBuffer = vertexBuffer;
}

绑定渲染缓存区和帧缓存区

- (void)bindRenderLayer:(CALayer <EAGLDrawable> *)layer {
    
    //1.渲染缓存区,帧缓存区对象
    GLuint renderBuffer;
    GLuint frameBuffer;
    
    //2.获取帧渲染缓存区名称,绑定渲染缓存区以及将渲染缓存区与layer建立连接
    glGenRenderbuffers(1, &renderBuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
    [self.context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer];
    
    //3.获取帧缓存区名称,绑定帧缓存区以及将渲染缓存区附着到帧缓存区上
    glGenFramebuffers(1, &frameBuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
    
    glFramebufferRenderbuffer(GL_FRAMEBUFFER,
                              GL_COLOR_ATTACHMENT0,
                              GL_RENDERBUFFER,
                              renderBuffer);
}

从图片中加载纹理

- (GLuint)createTextureWithImage:(UIImage *)image {
    
    //1、将 UIImage 转换为 CGImageRef
    CGImageRef cgImageRef = [image CGImage];
    //判断图片是否获取成功
    if (!cgImageRef) {
        NSLog(@"Failed to load image");
        exit(1);
    }
    //2、读取图片的大小，宽和高
    GLuint width = (GLuint)CGImageGetWidth(cgImageRef);
    GLuint height = (GLuint)CGImageGetHeight(cgImageRef);
    //获取图片的rect
    CGRect rect = CGRectMake(0, 0, width, height);
    
    //获取图片的颜色空间
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    //3.获取图片字节数 宽*高*4（RGBA）
    void *imageData = malloc(width * height * 4);
    //4.创建上下文
    /*
     参数1：data,指向要渲染的绘制图像的内存地址
     参数2：width,bitmap的宽度，单位为像素
     参数3：height,bitmap的高度，单位为像素
     参数4：bitPerComponent,内存中像素的每个组件的位数，比如32位RGBA，就设置为8
     参数5：bytesPerRow,bitmap的没一行的内存所占的比特数
     参数6：colorSpace,bitmap上使用的颜色空间  kCGImageAlphaPremultipliedLast：RGBA
     */
    CGContextRef context = CGBitmapContextCreate(imageData, width, height, 8, width * 4, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    
    //将图片翻转过来(图片默认是倒置的)
    CGContextTranslateCTM(context, 0, height);
    CGContextScaleCTM(context, 1.0f, -1.0f);
    CGColorSpaceRelease(colorSpace);
    CGContextClearRect(context, rect);
    
    //对图片进行重新绘制，得到一张新的解压缩后的位图
    CGContextDrawImage(context, rect, cgImageRef);
    
    //设置图片纹理属性
    //5. 获取纹理ID
    GLuint textureID;
    glGenTextures(1, &textureID);
    glBindTexture(GL_TEXTURE_2D, textureID);
    
    //6.载入纹理2D数据
    /*
     参数1：纹理模式，GL_TEXTURE_1D、GL_TEXTURE_2D、GL_TEXTURE_3D
     参数2：加载的层次，一般设置为0
     参数3：纹理的颜色值GL_RGBA
     参数4：宽
     参数5：高
     参数6：border，边界宽度
     参数7：format
     参数8：type
     参数9：纹理数据
     */
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
    
    //7.设置纹理属性
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    
    //8.绑定纹理
    /*
     参数1：纹理维度
     参数2：纹理ID,因为只有一个纹理，给0就可以了。
     */
    glBindTexture(GL_TEXTURE_2D, 0);
    
    //9.释放context,imageData
    CGContextRelease(context);
    free(imageData);
    
    //10.返回纹理ID
    return textureID;
}

开始一个滤镜动画

- (void)startFilerAnimation {
    //1.判断displayLink 是否为空
    //CADisplayLink 定时器
    if (self.displayLink) {
        [self.displayLink invalidate];
        self.displayLink = nil;
    }
    //2. 设置displayLink 的方法
    self.startTimeInterval = 0;
    self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(timeAction)];
    
    //3.将displayLink 添加到runloop 运行循环
    [self.displayLink addToRunLoop:[NSRunLoop mainRunLoop]
                           forMode:NSRunLoopCommonModes];
}

动画

- (void)timeAction {
    //DisplayLink 的当前时间撮
    if (self.startTimeInterval == 0) {
        self.startTimeInterval = self.displayLink.timestamp;
    }
    //使用program
    glUseProgram(self.program);
    //绑定buffer
    glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer);
    
    // 传入时间
    CGFloat currentTime = self.displayLink.timestamp - self.startTimeInterval;
    NSLog(@"currentTime = %f", currentTime);
    GLuint time = glGetUniformLocation(self.program, "Time");
    glUniform1f(time, currentTime);
    
    // 清除画布
    glClearColor(1, 1, 1, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    
    // 重绘
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    //渲染到屏幕上
    [self.context presentRenderbuffer:GL_RENDERBUFFER];
}

初始化着色器程序

- (void)setupShaderProgramWithName:(NSString *)name {
    //1. 获取着色器program
    GLuint program = [self programWithShaderName:name];
    
    //2. use Program
    glUseProgram(program);
    
    //3. 获取Position,Texture,TextureCoords 的索引位置
    GLuint positionSlot = glGetAttribLocation(program, "Position");
    GLuint textureSlot = glGetUniformLocation(program, "Texture");
    GLuint textureCoordsSlot = glGetAttribLocation(program, "TextureCoords");
    
    //4.激活纹理,绑定纹理ID
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, self.textureID);
    
    //5.纹理sample
    glUniform1i(textureSlot, 0);
    
    //6.打开positionSlot 属性并且传递数据到positionSlot中(顶点坐标)
    glEnableVertexAttribArray(positionSlot);
    glVertexAttribPointer(positionSlot, 3, GL_FLOAT, GL_FALSE, sizeof(SenceVertex), NULL + offsetof(SenceVertex, positionCoord));
    
    //7.打开textureCoordsSlot 属性并传递数据到textureCoordsSlot(纹理坐标)
    glEnableVertexAttribArray(textureCoordsSlot);
    glVertexAttribPointer(textureCoordsSlot, 2, GL_FLOAT, GL_FALSE, sizeof(SenceVertex), NULL + offsetof(SenceVertex, textureCoord));
    
    //8.保存program,界面销毁则释放
    self.program = program;
}

初始化程序对象

- (GLuint)programWithShaderName:(NSString *)shaderName {
    //1. 编译顶点着色器/片元着色器
    GLuint vertexShader = [self compileShaderWithName:shaderName type:GL_VERTEX_SHADER];
    GLuint fragmentShader = [self compileShaderWithName:shaderName type:GL_FRAGMENT_SHADER];
    
    //2. 将顶点/片元附着到program
    GLuint program = glCreateProgram();
    glAttachShader(program, vertexShader);
    glAttachShader(program, fragmentShader);
    
    //3.linkProgram
    glLinkProgram(program);
    
    //4.检查是否link成功
    GLint linkSuccess;
    glGetProgramiv(program, GL_LINK_STATUS, &linkSuccess);
    if (linkSuccess == GL_FALSE) {
        GLchar messages[256];
        glGetProgramInfoLog(program, sizeof(messages), 0, &messages[0]);
        NSString *messageString = [NSString stringWithUTF8String:messages];
        NSAssert(NO, @"program链接失败：%@", messageString);
        exit(1);
    }
    //5.返回program
    return program;
}

编译shader代码

- (GLuint)compileShaderWithName:(NSString *)name type:(GLenum)shaderType {
    
    //1.获取shader 路径
    NSString *shaderPath = [[NSBundle mainBundle] pathForResource:name ofType:shaderType == GL_VERTEX_SHADER ? @"vsh" : @"fsh"];
    NSError *error;
    NSString *shaderString = [NSString stringWithContentsOfFile:shaderPath encoding:NSUTF8StringEncoding error:&error];
    if (!shaderString) {
        NSAssert(NO, @"读取shader失败");
        exit(1);
    }
    
    //2. 创建shader->根据shaderType
    GLuint shader = glCreateShader(shaderType);
    
    //3.获取shader source
    const char *shaderStringUTF8 = [shaderString UTF8String];
    int shaderStringLength = (int)[shaderString length];
    glShaderSource(shader, 1, &shaderStringUTF8, &shaderStringLength);
    
    //4.编译shader
    glCompileShader(shader);
    
    //5.查看编译是否成功
    GLint compileSuccess;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &compileSuccess);
    if (compileSuccess == GL_FALSE) {
        GLchar messages[256];
        glGetShaderInfoLog(shader, sizeof(messages), 0, &messages[0]);
        NSString *messageString = [NSString stringWithUTF8String:messages];
        NSAssert(NO, @"shader编译失败：%@", messageString);
        exit(1);
    }
    //6.返回shader
    return shader;
}

获取渲染缓存区的宽

- (GLint)drawableWidth {
    GLint backingWidth;
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
    return backingWidth;
}

获取渲染缓存区的高

- (GLint)drawableHeight {
    GLint backingHeight;
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);
    return backingHeight;
}

最后附上github地址
https://github.com/LoveToday/VideoFilter.git