How do I capture a video in a tensor4d on tensorflow.js?

I'm trying to build a web application that captures a series of images that need to be evenly spaced. I've noticed that the capture() function on tf.data.webcam() takes a variable amount of time. Is there a workaround to capture images evenly spaced in time OR capture a video in a tensor4d element so that I can get evenly spaced slices?