Использование opengl es shader для преобразования YUV в RGB

Question

Я хочу преобразовать yuv в rgb в opengl es shader с помощью всего одного сэмплера, который содержит данные yuv. Мой код ниже:

1) Я посылаю данные YUV текстуре:

GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_LUMINANCE, 
      mData.w, mData.h * 3/2, 0, GLES20.GL_LUMINANCE, 
      GLES20.GL_UNSIGNED_BYTE, ByteBuffer.wrap(mData.yuv)); 

2) Моя вершинного шейдера:

attribute vec4 position; 
attribute vec2 inputTextureCoordinate; 
attribute mediump float width; 

varying vec2 v_texCoord; 
varying mediump vec2 v_vuTexCoord; 
varying mediump float x_coord; 

void main() 
{ 
    gl_Position = position; 
    v_texCoord = vec2(inputTextureCoordinate.x, inputTextureCoordinate.y * 0.6666667); 
    v_vuTexCoord = vec2(inputTextureCoordinate.x, inputTextureCoordinate.y * 0.333333 + 0.6666667); 
    x_coord = floor(inputTextureCoordinate.x * width); 
} 

3) Мой пиксельный шейдер:

uniform sampler2D inputImageTexture; 
varying mediump vec2 v_texCoord; 
varying mediump vec2 v_vuTexCoord; 
varying mediump float x_coord; 
uniform mediump float u_one_over_tex_size; 

void main() 
{ 
    mediump vec3 yuv; 
    mediump vec3 rgb; 
    mediump float valx = mod(x_coord , 2.0); 
    if(valx < 1.0) 
    { 
     yuv.y = texture2D(inputImageTexture, v_vuTexCoord + vec2(u_one_over_tex_size, 0)).r - 0.5; 
     yuv.z = texture2D(inputImageTexture, v_vuTexCoord).r - 0.5; 
    } 
    else { 
     yuv.y = texture2D(inputImageTexture, v_vuTexCoord).r - 0.5; 
     yuv.z = texture2D(inputImageTexture, v_vuTexCoord + vec2(u_one_over_tex_size, 0)).r - 0.5; 
    } 
    yuv.x = texture2D(inputImageTexture, v_texCoord).r; 
    rgb = mat3( 1,  1,  1, 
        0, -.34413, 1.772, 
       1.402, -.71414,  0) * yuv; 
    gl_FragColor = vec4(rgb, 1); 
} 

Но результат не такой, как я думал. Если я разделяю данные yuv на пробоотборники y и uv и меняю вершинный и фрагментарный шейдер, и я могу получить правильный результат. Но как я мог только отправить сэмплер только
, как указано выше?

Answer 1

Посмотрите на код здесь: http://www.fourcc.org/source/YUV420P-OpenGL-GLSLang.c

/* 
* Very simple example of how to perform YUV->RGB (YCrCb->RGB) 
* conversion with an OpenGL fragmen shader. The data (not included) 
* is presumed to be three files with Y, U and V samples for a 720x576 
* pixels large image. 
* 
* Note! The example uses NVidia extensions for rectangular textures 
* to make it simpler to read (non-normalised coordinates). 
* Rewriting it without the extensions is quite simple, but left as an 
* exercise to the reader. (The trick is that the shader must know the 
* image dimensions instead) 
* 
* The program also does not check to see if the shader extensions are 
* available - this is after all just a simple example. 
* 
* This code is released under a BSD style license. Do what you want, but 
* do not blame me. 
* 
* Peter Bengtsson, Dec 2004. 
*/ 

#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <GL/gl.h> 
#include <GL/glext.h> 
#include <SDL/SDL.h> 

int Quit=0; 

static int B_WIDTH=640; 
static int B_HEIGHT=480; 

int main(int cnt,char *arg[]) 
{ 
SDL_Surface *Win=NULL; 
GLubyte *Ytex,*Utex,*Vtex; 
SDL_Event evt; 
int i; 
GLhandleARB FSHandle,PHandle; 
char *s; 
FILE *fp; 

char *FProgram= 
    "uniform sampler2DRect Ytex;\n" 
    "uniform sampler2DRect Utex,Vtex;\n" 
    "void main(void) {\n" 
    " float nx,ny,r,g,b,y,u,v;\n" 
    " vec4 txl,ux,vx;" 
    " nx=gl_TexCoord[0].x;\n" 
    " ny=576.0-gl_TexCoord[0].y;\n" 
    " y=texture2DRect(Ytex,vec2(nx,ny)).r;\n" 
    " u=texture2DRect(Utex,vec2(nx/2.0,ny/2.0)).r;\n" 
    " v=texture2DRect(Vtex,vec2(nx/2.0,ny/2.0)).r;\n" 

    " y=1.1643*(y-0.0625);\n" 
    " u=u-0.5;\n" 
    " v=v-0.5;\n" 

    " r=y+1.5958*v;\n" 
    " g=y-0.39173*u-0.81290*v;\n" 
    " b=y+2.017*u;\n" 

    " gl_FragColor=vec4(r,g,b,1.0);\n" 
    "}\n"; 


if(!SDL_Init(SDL_INIT_VIDEO)) { 

    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1); 

    Win=SDL_SetVideoMode(B_WIDTH,B_HEIGHT,32,SDL_HWSURFACE|SDL_ANYFORMAT|SDL_OPENGL); 

    if(Win) { 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    glOrtho(0,B_WIDTH,0,B_HEIGHT,-1,1); 
    glViewport(0,0,B_WIDTH,B_HEIGHT); 
    glClearColor(0,0,0,0); 
    glColor3f(1.0,0.84,0.0); 
    glHint(GL_POLYGON_SMOOTH_HINT,GL_NICEST); 

    /* Set up program objects. */ 
    PHandle=glCreateProgramObjectARB(); 
    FSHandle=glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB); 

    /* Compile the shader. */ 
    glShaderSourceARB(FSHandle,1,&FProgram,NULL); 
    glCompileShaderARB(FSHandle); 

    /* Print the compilation log. */ 
    glGetObjectParameterivARB(FSHandle,GL_OBJECT_COMPILE_STATUS_ARB,&i); 
    s=malloc(32768); 
    glGetInfoLogARB(FSHandle,32768,NULL,s); 
    printf("Compile Log: %s\n", s); 
    free(s); 

    /* Create a complete program object. */ 
    glAttachObjectARB(PHandle,FSHandle); 
    glLinkProgramARB(PHandle); 

    /* And print the link log. */ 
    s=malloc(32768); 
    glGetInfoLogARB(PHandle,32768,NULL,s); 
    printf("Link Log: %s\n", s); 
    free(s); 

    /* Finally, use the program. */ 
    glUseProgramObjectARB(PHandle); 

    /* Load the textures. */ 
    Ytex=malloc(414720); 
    Utex=malloc(103680); 
    Vtex=malloc(103680); 

    fp=fopen("Image.Y","rb"); 
    fread(Ytex,414720,1,fp); 
    fclose(fp); 
    fp=fopen("Image.U","rb"); 
    fread(Utex,103680,1,fp); 
    fclose(fp); 
    fp=fopen("Image.V","rb"); 
    fread(Vtex,103680,1,fp); 
    fclose(fp); 

    /* This might not be required, but should not hurt. */ 
    glEnable(GL_TEXTURE_2D); 

    /* Select texture unit 1 as the active unit and bind the U texture. */ 
    glActiveTexture(GL_TEXTURE1); 
    i=glGetUniformLocationARB(PHandle,"Utex"); 
    glUniform1iARB(i,1); /* Bind Utex to texture unit 1 */ 
    glBindTexture(GL_TEXTURE_RECTANGLE_NV,1); 

    glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MAG_FILTER,GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MIN_FILTER,GL_LINEAR); 
    glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_DECAL); 
    glTexImage2D(GL_TEXTURE_RECTANGLE_NV,0,GL_LUMINANCE,376,288,0,GL_LUMINANCE,GL_UNSIGNED_BYTE,Utex); 

    /* Select texture unit 2 as the active unit and bind the V texture. */ 
    glActiveTexture(GL_TEXTURE2); 
    i=glGetUniformLocationARB(PHandle,"Vtex"); 
    glBindTexture(GL_TEXTURE_RECTANGLE_NV,2); 
    glUniform1iARB(i,2); /* Bind Vtext to texture unit 2 */ 

    glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MAG_FILTER,GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MIN_FILTER,GL_LINEAR); 
    glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_DECAL); 
    glTexImage2D(GL_TEXTURE_RECTANGLE_NV,0,GL_LUMINANCE,376,288,0,GL_LUMINANCE,GL_UNSIGNED_BYTE,Vtex); 

    /* Select texture unit 0 as the active unit and bind the Y texture. */ 
    glActiveTexture(GL_TEXTURE0); 
    i=glGetUniformLocationARB(PHandle,"Ytex"); 
    glUniform1iARB(i,0); /* Bind Ytex to texture unit 0 */ 
    glBindTexture(GL_TEXTURE_RECTANGLE_NV,3); 

    glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MAG_FILTER,GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MIN_FILTER,GL_LINEAR); 
    glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_DECAL); 
    glTexImage2D(GL_TEXTURE_RECTANGLE_NV,0,GL_LUMINANCE,752,576,0,GL_LUMINANCE,GL_UNSIGNED_BYTE,Ytex); 

    /* Simple loop, just draws the image and waits for quit. */ 
    while(!Quit) { 
     if(SDL_PollEvent(&evt)) { 
     switch(evt.type) { 
     case SDL_KEYDOWN: 
     case SDL_QUIT: 
      Quit=1; 
     break; 
     } 
     } 

     glClear(GL_COLOR_BUFFER_BIT); 

     /* Draw image (again and again). */ 

     glBegin(GL_QUADS); 
     glTexCoord2i(0,0); 
     glVertex2i(0,0); 
     glTexCoord2i(720,0); 
     glVertex2i(B_WIDTH,0); 
     glTexCoord2i(720,576); 
     glVertex2i(B_WIDTH,B_HEIGHT); 
     glTexCoord2i(0,576); 
     glVertex2i(0,B_HEIGHT); 
     glEnd(); 

     /* Flip buffers. */ 

     glFlush(); 
     SDL_GL_SwapBuffers(); 

     sleep(1); 
    } /* while(!Quit) */ 

    /* Clean up before exit. */ 

    glUseProgramObjectARB(0); 
    glDeleteObjectARB(sprog); 

    free(Ytex); 
    free(Utex); 
    free(Vtex); 

    } else { 
    fprintf(stderr,"Unable to create primary surface. \"%s\".\n",SDL_GetError()); 
    } 
    SDL_Quit(); 
} else { 
    fprintf(stderr,"Initialisation failed. \"%s\".\n",SDL_GetError()); 
} 

return(0); 
} 

Answer 2

Может быть, это вне темы, но here я реализовал YUV 4: 2: 2 v210 10-битный декодер в GLSL.