The video pipeline I've been building for two YouTube channels running off this monorepo started with short-form vertical clips — a single narrator, a single slide, done. Longform is different. A ten-minute explainer with one voice and no conversational variation is hard to watch even when the content is good. I wanted something that felt like two people talking through a problem, not a text-to-speech audiobook.
The solution was a two-host dialogue spec: a JSON file where each line of audio is tagged with a speaker (A or B), and the build script renders it as a full-length video alternating between two neural voices.
What the spec looks like
The simplest possible spec:
{
