Update mp4.R

[EvaMaeRey]

numeric pointer to the slides that should be included?

[jhelvy]

Ah, good idea. I do this with build_png() but I didn't include it for mp4, gif, or pptx, which all build from the pdf. I'll pull in this request then I'll make some quick modifications to it so that it's properly documented and so that the argument names match (I use slides for build_png(), so I'll use that instead of which.

[jhelvy]

Okay, I think I've got everything harmonized now with the last commit. Could you try build_mp4() with the latest version to see if the slides argument works to only build the vector of specified slide numbers? Should also work for build_gif() and build_pptx().

[EvaMaeRey]

Great! Thanks! 👍