At long last we're finally bringing this feature back. In order to accomplish this, we've had to make our own modifications to ffmpeg to add support for doing this.
Current supported server platforms: All except Synology.
You'll notice the setting:
When enabled, if the transcoding process gets really far ahead of your watching position, then the throttling will kick in and you'll see cpu usage plummet:
Please try it out. Thanks.
What happens if I replace Emby's ffmpeg builds with my own? Emby will think the feature is supported, but it won't work if you activate it.