The mouse speed functions return the number of pixels the mouse has moved. Changing it would be nonsensical.
I'll bet you're just running your game, or windows, in a different resolution.
The solution is to code a custom mouse speed function which takes into account the resolution, assuming that windows does not change the mouse speed depending on resolution. I'm not sure if it does or not.
If it does, then using floating point values, divide the speed by the resolution, and either use that, or multiply by your chosen base resolution, ie, 1024x768, to convert to pixels in that res.
You can also average the mouse position over two frames to smooth out the motion more.
I'll bet you're just running your game, or windows, in a different resolution.
The solution is to code a custom mouse speed function which takes into account the resolution, assuming that windows does not change the mouse speed depending on resolution. I'm not sure if it does or not.
If it does, then using floating point values, divide the speed by the resolution, and either use that, or multiply by your chosen base resolution, ie, 1024x768, to convert to pixels in that res.
You can also average the mouse position over two frames to smooth out the motion more.