I have the MiBox, and mirroring video content...well it just doesn't work well enough. The sound coming out of my Macbook is playing well, well before the video being displayed on the TV. Do things like the Apple TV or others work better for this, or is the input lag pretty standard across the board?
Apple TV is solid for Apple displaying mirroring. I also like the app Airpin Pro on my Nvidia shield for such things. No serious lag.
Nvidia Shield. Use GeForce Now or Steamlink app.
It might just be network latency, are both devices on WiFi?
Why would you output sound from the macbook while showing video on the TV? Doesn't the TV have speakers?
I have found the Mi Box S to do a better job than my Roku at mirroring when I'm using the Chromecast portion of the Mi Box S vs whatever Roku calls their mirroring (Mirrorcast?). Even given that, Casting the Roku Channel from my laptop to my Mi Box S doesn't work very well -- I get some stuttering but the video and audio are both sent to my TV and are in sync.