opengl video freeze

Question

I have an IDS ueye cam and proceed the capture via PBO to OpenGL (OpenTK). On my developer-pc it works great, but on slower machines the video freezes after some time.

Code for allocating memory via opengl and map to ueye, so camera saves processed images in here:

// Generate PBO and save id
GL.GenBuffers(1, out this.frameBuffer[i].BufferID);

// Define the type of the buffer.
GL.BindBuffer(BufferTarget.PixelUnpackBuffer, this.frameBuffer[i].BufferID);

// Define buffer size.
GL.BufferData(BufferTarget.PixelUnpackBuffer, new IntPtr(width * height * depth), IntPtr.Zero, BufferUsageHint.StreamDraw);

// Get pointer to by openGL allocated buffer and
// lock global with uEye.
this.frameBuffer[i].PointerToNormalMemory = GL.MapBuffer(BufferTarget.PixelUnpackBuffer, BufferAccess.WriteOnly);
this.frameBuffer[i].PointerToLockedMemory = uEye.GlobalLock(this.frameBuffer[i].PointerToNormalMemory);

// Unmap PBO after use.
GL.UnmapBuffer(BufferTarget.PixelUnpackBuffer);

// Set selected PBO to none.
GL.BindBuffer(BufferTarget.PixelUnpackBuffer, 0);

// Register buffer to uEye
this.Succeeded("SetAllocatedImageMem", this.cam.SetAllocatedImageMem(width, height, depth, this.frameBuffer[i].PointerToLockedMemory, ref this.frameBuffer[i].MemId));

// Add buffer to uEye-Ringbuffer
this.Succeeded("AddToSequence", this.cam.AddToSequence(this.frameBuffer[i].PointerToLockedMemory, this.frameBuffer[i].MemId));

To copy the image from pbo to an texture (Texture is created and ok):

// Select PBO with new video image
GL.BindBuffer(BufferTarget.PixelUnpackBuffer, nextBufferId);

// Select videotexture as current
GL.BindTexture(TextureTarget.Texture2D, this.videoTextureId);

// Copy PBO to texture            
GL.TexSubImage2D(
    TextureTarget.Texture2D,
    0,
    0,
    0,
    nextBufferSize.Width,
    nextBufferSize.Height,
    OpenTK.Graphics.OpenGL.PixelFormat.Bgr,
    PixelType.UnsignedByte,
    IntPtr.Zero);

// Release Texture
GL.BindTexture(TextureTarget.Texture2D, 0);

// Release PBO
GL.BindBuffer(BufferTarget.PixelUnpackBuffer, 0);

Maybe someone can see the mistake... After about 6 seconds the ueye events don't deliver any images any more. When I remove TexSubImage2D it works well, but of course no image appears. Is there maybe a lock or something from opengl? Thanks in advance - Thomas

Answer 1

it seems like a shared buffer problem. you may try to implement a simple queue mechanism to get rid of that problem.

sample code (not meant to be working):

queue< vector<BYTE> > frames;

...

frames.push(vector<BYTE>(frameBuffer, frameBuffer + frameSize));

...

// use frame here at GL.TexSubImage2D using frames.front()
frames.pop();

Answer 2

Found the failure by myself. Just replace in the code above StreamDraw with StreamRead.

GL.BufferData(BufferTarget.PixelUnpackBuffer, new IntPtr(width * height * depth), IntPtr.Zero, BufferUsageHint.StreamRead);