> By running all encoder instances in parallel, better parallelism can be obtained overall.

This makes a lot of sense for the live-streaming use case, and some sense for just generally transcoding a video into multiple formats. But I would love to see time-axis parallelization in ffmpeg. Basically quickly split the input video into keyframe chunks then encode each keyframe in parallel. This would allow excellent parallelization even when only producing a single output. (And without lowering video quality as most intra-frame parallelization does)