objective-c - OSX 上的 NSOpenGL I420 YUV 缓冲区渲染

Question

在我的应用程序中，我必须显示从服务器接收到的 YUV 帧，YUV 图像格式是 I420，

我有这样的子类 NSOpenGLView，

@interface RTCNSGLVideoView : NSOpenGLView <RTCVideoRenderer>

和 OpenGL 视图在视图上创建类似这样的东西，

if ( bUsingOpenGL && !pVideoRTCGLView){
    NSOpenGLPixelFormatAttribute attributes[] = {
        NSOpenGLPFADoubleBuffer,
        NSOpenGLPFADepthSize, 24,
        NSOpenGLPFAOpenGLProfile,
        NSOpenGLProfileVersion3_2Core,
        0
    };
    NSRect frameRect = [pImageView frame];



    NSOpenGLPixelFormat* pixelFormat =
    [[NSOpenGLPixelFormat alloc] initWithAttributes:attributes];
    pVideoRTCGLView = [[RTCNSGLVideoView alloc] initWithFrame:frameRect
                                                   pixelFormat:pixelFormat];
    [pVideoRTCGLView setAutoresizingMask:[pImageView autoresizingMask]];
    [pVideoRTCGLView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [pVideoRTCGLView setYUVFrameDelegate:self];
    [[[self window] contentView] addSubview:pVideoRTCGLView];
    [pVideoRTCGLView prepareOpenGL];
}

我直接在屏幕上显示I420，为此，顶点和着色器程序是这样的，

#define RTC_PIXEL_FORMAT GL_RED
#define SHADER_VERSION "#version 150\n"
#define VERTEX_SHADER_IN "in"
#define VERTEX_SHADER_OUT "out"
#define FRAGMENT_SHADER_IN "in"
#define FRAGMENT_SHADER_OUT "out vec4 fragColor;\n"
#define FRAGMENT_SHADER_COLOR "fragColor"
#define FRAGMENT_SHADER_TEXTURE "texture"
#endif

// Vertex shader doesn't do anything except pass coordinates through.
static const char kVertexShaderSource[] =
  SHADER_VERSION
  VERTEX_SHADER_IN " vec2 position;\n"
  VERTEX_SHADER_IN " vec2 texcoord;\n"
  VERTEX_SHADER_OUT " vec2 v_texcoord;\n"
  "void main() {\n"
  "    gl_Position = vec4(position.x, position.y, 0.0, 1.0);\n"
  "    v_texcoord = texcoord;\n"
  "}\n";

// Fragment shader converts YUV values from input textures into a final RGB
// pixel. The conversion formula is from http://www.fourcc.org/fccyvrgb.php.
static const char kFragmentShaderSource[] =
  SHADER_VERSION
  "precision highp float;"
  FRAGMENT_SHADER_IN " vec2 v_texcoord;\n"
  "uniform lowp sampler2D s_textureY;\n"
  "uniform lowp sampler2D s_textureU;\n"
  "uniform lowp sampler2D s_textureV;\n"
  FRAGMENT_SHADER_OUT
  "void main() {\n"
  "    float y, u, v, r, g, b;\n"
  "    y = " FRAGMENT_SHADER_TEXTURE "(s_textureY, v_texcoord).r;\n"
  "    u = " FRAGMENT_SHADER_TEXTURE "(s_textureU, v_texcoord).r;\n"
  "    v = " FRAGMENT_SHADER_TEXTURE "(s_textureV, v_texcoord).r;\n"
  "    u = u - 0.5;\n"
  "    v = v - 0.5;\n"
  "    r = y + 1.403 * v;\n"
  "    g = y - 0.344 * u - 0.714 * v;\n"
  "    b = y + 1.770 * u;\n"
  "    " FRAGMENT_SHADER_COLOR " = vec4(r, g, b, 1.0);\n"
  "  }\n";

// Compiles a shader of the given |type| with GLSL source |source| and returns
// the shader handle or 0 on error.
GLuint CreateShader(GLenum type, const GLchar* source) {
  GLuint shader = glCreateShader(type);
  if (!shader) {
    return 0;
  }
  glShaderSource(shader, 1, &source, NULL);
  glCompileShader(shader);
  GLint compileStatus = GL_FALSE;
  glGetShaderiv(shader, GL_COMPILE_STATUS, &compileStatus);
  if (compileStatus == GL_FALSE) {
    glDeleteShader(shader);
    shader = 0;
  }
  return shader;
}

// Links a shader program with the given vertex and fragment shaders and
// returns the program handle or 0 on error.
GLuint CreateProgram(GLuint vertexShader, GLuint fragmentShader) {
  if (vertexShader == 0 || fragmentShader == 0) {
    return 0;
  }
  GLuint program = glCreateProgram();
  if (!program) {
    return 0;
  }
  glAttachShader(program, vertexShader);
  glAttachShader(program, fragmentShader);
  glLinkProgram(program);
  GLint linkStatus = GL_FALSE;
  glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
  if (linkStatus == GL_FALSE) {
    glDeleteProgram(program);
    program = 0;
  }
  return program;
}

在子类视图中，我正在像这样设置视口大小，

- (void)reshape {
  [super reshape];
  NSRect frame = [self frame];
    NSLog(@"reshaping viewport (%@) ",NSStringFromRect(frame));
  CGLLockContext([[self openGLContext] CGLContextObj]);
  glViewport(0, 0, frame.size.width, frame.size.height);
  CGLUnlockContext([[self openGLContext] CGLContextObj]);
}

我看到的是底部和右侧有点损坏，请参考图片，

请帮助我，无法弄清楚，出了什么问题，

如果您参考图像，我在底部和右侧绘制了红色矩形，这是不必要的