ios - 在 iOS 4.3 中将 YpCbCr iPhone 4 相机帧渲染为 OpenGL ES 2.0 纹理

Question

我试图在 iPhone 4 上的 iOS 4.3 中将原生平面图像渲染为 OpenGL ES 2.0 纹理。然而，纹理最终变成全黑。我的相机配置如下:

[videoOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange] 
                                                          forKey:(id)kCVPixelBufferPixelFormatTypeKey]];

我像这样将像素数据传递给我的纹理:

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bufferWidth, bufferHeight, 0, GL_RGB_422_APPLE, GL_UNSIGNED_SHORT_8_8_REV_APPLE, CVPixelBufferGetBaseAddress(cameraFrame));

我的碎片着色器是:

varying highp vec2 textureCoordinate;

uniform sampler2D videoFrame; 

void main() { 
    lowp vec4 color; 
    color = texture2D(videoFrame, textureCoordinate); 
    lowp vec3 convertedColor = vec3(-0.87075, 0.52975, -1.08175); 
    convertedColor += 1.164 * color.g; // Y
    convertedColor += vec3(0.0, -0.391, 2.018) * color.b; // U
    convertedColor += vec3(1.596, -0.813, 0.0) * color.r; // V
    gl_FragColor = vec4(convertedColor, 1.0); 
} 

我的顶点着色器是

attribute vec4 position;
attribute vec4 inputTextureCoordinate;

varying vec2 textureCoordinate;

void main()
{
    gl_Position = position;
    textureCoordinate = inputTextureCoordinate.xy;
}

这在我处理 BGRA 图像时工作得很好，而我的片段着色器只工作

gl_FragColor = texture2D(videoFrame, textureCoordinate);

如果我在这里遗漏了什么怎么办？谢谢!

Answer 1

好的。我们在这里取得了成功。关键是将 Y 和 UV 作为两个单独的纹理传递给片段着色器。这是最终的着色器:

#ifdef GL_ES
precision mediump float;
#endif

varying vec2 textureCoordinate;

uniform sampler2D videoFrame; 
uniform sampler2D videoFrameUV;

const mat3 yuv2rgb = mat3(
                            1, 0, 1.2802,
                            1, -0.214821, -0.380589,
                            1, 2.127982, 0
                            );

void main() {    
    vec3 yuv = vec3(
                    1.1643 * (texture2D(videoFrame, textureCoordinate).r - 0.0625),
                    texture2D(videoFrameUV, textureCoordinate).r - 0.5,
                    texture2D(videoFrameUV, textureCoordinate).a - 0.5
                    );
    vec3 rgb = yuv * yuv2rgb;

    gl_FragColor = vec4(rgb, 1.0);
} 

您需要像这样创建纹理:

int bufferHeight = CVPixelBufferGetHeight(cameraFrame);
int bufferWidth = CVPixelBufferGetWidth(cameraFrame);
glBindTexture(GL_TEXTURE_2D, videoFrameTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, bufferWidth, bufferHeight, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddressOfPlane(cameraFrame, 0));

glBindTexture(GL_TEXTURE_2D, videoFrameTextureUV);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, bufferWidth/2, bufferHeight/2, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddressOfPlane(cameraFrame, 1));

然后像这样传递它们:

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, videoFrameTexture);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, videoFrameTextureUV);

glActiveTexture(GL_TEXTURE0);
glUniform1i(videoFrameUniform, 0);
glUniform1i(videoFrameUniformUV, 1);

child ，我松了一口气!

附言yuv2rgb 矩阵的值来自这里 http://en.wikipedia.org/wiki/YUV我从这里复制了代码 http://www.ogre3d.org/forums/viewtopic.php?f=5&t=25877弄清楚如何开始获得正确的 YUV 值。