Using FBO to render YUV data - opengl

Question

I was able to render YUV image on the screen using shaders.
To improve performance I want to use FBO. But I am not able to do it.
My initialization code is as below
void opengl_init(int w, int h) {
glGenFramebuffers(1, &framebuffer);
checkGlError("glGenFramebuffers");
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
checkGlError("glBindFramebuffer");
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &gYTexture);
glBindTexture(GL_TEXTURE_2D, gYTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, FRAME_WIDTH, FRAME_HEIGHT, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glBindTexture(GL_TEXTURE_2D, 0);
glGenRenderbuffers(1, &colorbuffer);
checkGlError("glGenRenderbuffers");
glBindRenderbuffer(GL_RENDERBUFFER, colorbuffer);
checkGlError("glBindRenderbuffer");
glRenderbufferStorage(GL_RENDERBUFFER,
GL_RGB565, FRAME_WIDTH, FRAME_HEIGHT);
checkGlError("glRenderbufferStorage");
glFramebufferRenderbuffer(GL_FRAMEBUFFER,
GL_COLOR_ATTACHMENT0,
GL_RENDERBUFFER, depthbuffer);
checkGlError("glFramebufferRenderbuffer");
glFramebufferTexture2D(GL_FRAMEBUFFER,
GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
gYTexture, 0);
checkGlError("glFramebufferTexture2D");
int status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
printf("Framebuffer is not complete: *status* = %d", status);
if (status != GL_FRAMEBUFFER_COMPLETE) {
printf("Framebuffer is not complete: *status* = %d", status);
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
checkGlError("glBindFramebuffer");
glGenBuffers(1, ioBuf);
checkGlError("glGenBuffers");
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &gUTexture);
glBindTexture(GL_TEXTURE_2D, gUTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glActiveTexture(GL_TEXTURE2);
glGenTextures(1, &gVTexture);
glBindTexture(GL_TEXTURE_2D, gVTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glViewport(0, 0, w, h);
checkGlError("glViewport");
}
I render my frame using the below code
void opengl_renderframe(void *yuvbuf,int framewidth, int frameheight) {
static void *ubuf, *vbuf;
ubuf = (char *)yuvbuf + (framewidth * frameheight);
vbuf = (char *)ubuf + ((framewidth * frameheight) / 4);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
checkGlError("glBindFramebuffer");
glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
checkGlError("glClearColor");
glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
checkGlError("glClear");
glUseProgram(gProgram);
checkGlError("glUseProgram");
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, gYTexture);
glBindBuffer(GL_ARRAY_BUFFER, ioBuf);
checkGlError("glBindBuffer");
glBufferData(GL_ARRAY_BUFFER, (FRAME_WIDTH * FRAME_HEIGHT) , yuvbuf, GL_STATIC_DRAW);
checkGlError("glBufferData");
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, FRAME_WIDTH, FRAME_HEIGHT, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
checkGlError("glTexImage2D");
glBindBuffer(GL_ARRAY_BUFFER, 0);
checkGlError("glBindBuffer");
glUniform1i(Ysamp, 0);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, gUTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, framewidth/2, frameheight/2, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, ubuf );
glUniform1i(Usamp, 1);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, gVTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, framewidth/2, frameheight/2, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, vbuf );
glUniform1i(Vsamp, 2);
glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
checkGlError("glVertexAttribPointer");
glEnableVertexAttribArray(gvPositionHandle);
checkGlError("glEnableVertexAttribArray");
glVertexAttribPointer(gaTextureCoordHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices2);
checkGlError("glVertexAttribPointer");
glEnableVertexAttribArray(gaTextureCoordHandle);
checkGlError("glEnableVertexAttribArray");
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
checkGlError("glDrawArrays");
glBindFramebuffer(GL_FRAMEBUFFER, 0);
checkGlError("glBindFramebuffer 0");
}
my fragment shader to render only Y data is as below
static const char gGrayScaleFragmentShader[] =
"precision mediump float;\n"
"varying vec2 vTextureCoord;\n"
"uniform sampler2D sTexture;\n"
"void main() {\n"
" gl_FragColor = texture2D(sTexture, vTextureCoord);\n"
"}\n";