gistfile1.c

  CFAbsoluteTime startTime = CFAbsoluteTimeGetCurrent();
    CVImageBufferRef cameraFrame = CMSampleBufferGetImageBuffer(sampleBuffer);
    
    int bufferWidth = CVPixelBufferGetWidth(cameraFrame);
    int bufferHeight = CVPixelBufferGetHeight(cameraFrame);

    int maxTextureSize;
     
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTextureSize);
    bufferWidth = MIN(bufferWidth, maxTextureSize);  // bad access here? for maxTextureSize
    bufferHeight = MIN(bufferHeight, maxTextureSize);
    
    CMTime currentTime = CMTimeMakeWithSeconds([[NSDate date] timeIntervalSinceDate:startingCaptureTime], 120);
    
    if ([GPUImageOpenGLESContext supportsFastTextureUpload])
    {
        CVPixelBufferLockBaseAddress(cameraFrame, 0);

        [GPUImageOpenGLESContext useImageProcessingContext];
        CVOpenGLESTextureRef texture = NULL;
        CVReturn err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, coreVideoTextureCache, cameraFrame, NULL, GL_TEXTURE_2D, GL_RGBA, bufferWidth, bufferHeight, GL_BGRA, GL_UNSIGNED_BYTE, 0, &texture);
                
        if (!texture || err) {
            NSLog(@"CVOpenGLESTextureCacheCreateTextureFromImage failed (error: %d)", err);  
            return;
        }