Phantomjs - no frames for animation

Question

I use phantomjs to take a screenshot from a d3 animation, and then merge the screenshots to create a video using ffmpeg. I am using the phantomjs render method to create a series of screenshots. But when the render method is used, I have to make the d3 animation too slow for the whole animation to be fixed smoothly. Even then, the framework seems to be missing. the animation doesn't look so smooth.

So, I came across another renderBuffer method that I saw in the phantom documentation. But this method, when they tried to execute it, even the sample code did not execute. I was hoping renderBuffer could solve the problem with the missing frame.

Anyone facing a similar problem or any methods that you guys could suggest to achieve smooth, continuous frames?