A rendition (also called a variant) is a single rung of the encoding ladder — one specific combination of resolution, bitrate, and usually codec that the player can choose to play. A title encoded with, say, six video qualities has six video renditions, plus separate renditions for each audio language and each subtitle track.
Renditions are what the manifest actually lists. When the player starts, it reads the manifest, sees the available renditions, and picks one to begin with; as throughput changes, ABR logic switches between renditions on segment boundaries. For switching to be seamless, all video renditions must be aligned — same segment durations, aligned keyframes, and a shared timeline — so the player can swap mid-stream without a visible glitch.
The number and spacing of renditions is a direct cost and quality decision: each one adds encoding compute and storage, and the gaps between them determine how smoothly quality adapts.
