OpenGL viedo rendering on iOS - ios

Question

I am working on video calling in PJSIP and i am facing an issue with rendering the video using openGL.
I am able to see the real time video but in green tint color, I presume that it is an issue with openGL texture.
I dont have any knowledge on openGL so i am pasting some openGL code snippets which I use in my application.
Please tell me where I am going wrong, all I need to do is somehow remove the green tint in the video.
Below is the code to the best of my knowledge
//YUV toRGB Vertex Shader
attribute vec4 position;
attribute vec2 textureCoordinate;
varying vec2 coordinate;
void main()
{
gl_Position = position;
coordinate = textureCoordinate.xy;
}
//YUV to RGB Fragment Shader
uniform sampler2D SamplerY;
uniform sampler2D SamplerUV;
varying highp vec2 coordinate;
void main()
{
mediump vec3 yuv;
lowp vec3 rgb;
yuv.x = texture2D(SamplerY, coordinate).r;
yuv.yz = texture2D(SamplerUV, coordinate).rg - vec2(0.5, 0.5);
rgb = mat3(1, 1, 1,
0, -.21482, 2.12798,
1.28033, -.38059, 0) * yuv;
gl_FragColor = vec4(rgb, 1);
}
static void uninitialize_gl_buffers(struct ios_stream *strm)
{
TRACE_((THIS_FILE, "uninitialize_gl_buffers"));
glDeleteFramebuffers(1, &strm->frameBufferHandle);
glDeleteRenderbuffers(1, &strm->colorBufferHandle);
}
static void initialize_gl_textures(struct ios_stream *strm)
{
TRACE_((THIS_FILE, "initialize_gl_textures"));
glGenTextures(1, &strm->lumaTexture);
glGenTextures(1, &strm->chromaUTexture);
glGenTextures(1, &strm->chromaVTexture);
}
static void uninitialize_gl_textures(struct ios_stream *strm)
{
TRACE_((THIS_FILE, "uninitialize_gl_textures"));
if (strm->lumaTexture) {
glDeleteTextures(1, &strm->lumaTexture);
strm->lumaTexture = 0;
}
if (strm->chromaUTexture) {
glDeleteTextures(1, &strm->chromaUTexture);
strm->chromaUTexture = 0;
}
if (strm->chromaVTexture) {
glDeleteTextures(1, &strm->chromaVTexture);
strm->chromaVTexture = 0;
}
}
static void allocate_gl_textures(struct ios_stream *strm,
int frameWidth, int frameHeight)
{
TRACE_((THIS_FILE, "allocate_gl_textures %dx%d", frameWidth, frameHeight));
// Y planes (init)
glActiveTexture(GL_TEXTURE0);
glGenTextures( 1, &strm->lumaTexture );
glBindTexture(GL_TEXTURE_2D, strm->lumaTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
//glEnable(GL_TEXTURE_2D);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, frameWidth, frameHeight, 0,
GL_LUMINANCE, GL_UNSIGNED_BYTE, 0);
// U-planes (init)
glActiveTexture(GL_TEXTURE1);
glGenTextures( 1, &strm->chromaUTexture );
glBindTexture(GL_TEXTURE_2D, strm->chromaUTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, frameWidth/2, frameHeight/2, 0,
GL_LUMINANCE, GL_UNSIGNED_BYTE, 0);
// V-plane (init)
glActiveTexture(GL_TEXTURE2);
glGenTextures( 1, &strm->chromaVTexture );
glBindTexture(GL_TEXTURE_2D, strm->chromaVTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, frameWidth/2, frameHeight/2, 0,
GL_LUMINANCE, GL_UNSIGNED_BYTE, 0);
}
static void update_gl_textures (struct ios_stream *strm)
{
//const pj_uint8_t *buffer = (const pj_uint8_t *)strm->buf;
const pj_uint8_t *buffer = (const pj_uint8_t *)strm->frame->buf;
pj_uint32_t width = strm->size.w;
pj_uint32_t height = strm->size.h;
//TRACE_((THIS_FILE, "update_gl_textures %dx%d (%d)", width, height, buffer));
// Y planes (update)
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, strm->lumaTexture);
glUniform1i(uniformLocations[UNIFORM_Y], 0);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0,
width, // source width
height, // source height
GL_LUMINANCE, GL_UNSIGNED_BYTE,
buffer);
// U-planes (update)
buffer += width*height;
width >>= 1;
height >>=1;
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, strm->chromaUTexture);
glUniform1i(uniformLocations[UNIFORM_U], 1);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0,
width, // source width
height, // source height
GL_LUMINANCE, GL_UNSIGNED_BYTE,
buffer);
// V-planes (update)
buffer += width*height;
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, strm->chromaVTexture);
glUniform1i(uniformLocations[UNIFORM_V], 2);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0,
width, // source width
height, // source height
GL_LUMINANCE, GL_UNSIGNED_BYTE,
buffer);
}