Inverted text for layers below?

Hi,

I am trying to make a lyric video, and have made a black and white only video, and want to have either black or white text in front of it.

The problem is, of course if the text is white, it can't be seen over the background, and if it's black it can't be seen over the images.

Is there a way I can invert the text, dependant on the colour below it? I have tried Auto Tracing the layers, but have not yet achieved a good fix.

Thanks