Can I add a custom synchronous meta channel to H264 or VP8?

I am new to video codec specs, so maybe this a noob question :)

I want to encode frame synchronous meta data with a web video. Is there a standard way with H264/265 OR VP8 to do that? What do I have to Google for?

If not, can I use off screen annotations somehow? So encode the info into certain unshown pixels? Will this technique survive encoding?

Thanks for all hints!