I compared the new Xiaomi Mijia with YI 4K Action Camera, GoPro Hero5 black & Hawkeye Firefly 8S.
incl. Spec Comparison, Audio Test, Image Stabilization - EIS - Demo and 4K footage.

Cameras:
Xiaomi Mijia 4K: https://bit.ly/2IudwvM or https://amzn.to/2DuWQym
YI 4K: https://amzn.to/32DvrYg
GoPro Hero5: https://amzn.to/2K4Mb49
Firefly 8SE - New! with Touchscreen: http://bit.ly/2BoOOHc

Here's a new camera I can recommend - Insta360 One R
It's a module camera and works as Action Camera and 360° camera - check it out:
https://elproducente.com/best-360-act...

☞ Camera Info:
☞ GoPro Hero5:
Sensor: 12 MP Sony Sensor
Processor: Ambarella A9
Video Resolutions:
4K - 30 fps
1080p - max. 120 fps
720p - max. 240 fps
Photo Resolution: 12 MP, jpg & RAW
2" Touchscreen
Battery: 1220 mAh
Image Stabilisation up to 2.7K 60fps
wifi: yes
bluetooth: yes
Remote Controller: available but not included
USB-C port: external microphone available
HDMI port

☞ YI 4K Action Camera:
Sensor: 12 MP Sony Sensor - IMX317
Processor: Ambarella A9
Video Resolutions:
4K - 30 fps
1080p - max. 120 fps
720p - max. 240 fps
Photo Resolution: 12 MP, jpg & RAW
2.19" Touchscreen
Battery: 1400 mAh
Image Stabilisation up to 2.7K 60fps
wifi: yes
bluetooth: yes
Remote Controller: available but not included
micro USB port: external microphone not available
no HDMI port

☞ Firefly 8S:
Sensor: 12 MP Sony Sensor - IMX117
Processor: Ambarella A12
Video Resolutions:
4K - 30 fps
1080p - max. 120 fps
720p - max. 240 fps
Photo Resolution: 12 MP, jpg
2" live view
Battery: 1200 mAh
Image Stabilisation up to 1080p 60fps
wifi: yes
bluetooth: yes
Remote Controller: available but not included
mini USB port: external microphone available
HDMI port

☞ Xiaomi Mijia Action Camera:
Sensor: 8 MP Sony Sensor - IMX377
Processor: Ambarella A12
Video Resolutions:
4K - 30 fps
1080p - max. 120 fps
720p - max. 240 fps
Photo Resolution: 8MP, jpg & RAW .dng
2.44" Touchscreen
Battery: 1450 mAh
Image Stabilisation up to 1080p 60fps
wifi: yes
bluetooth: yes
Remote Controller: available but not included
micro USB port: no external microphone
no HDMI port

Giveaway info:
Everyone is applicable to win, after subscribing to my YouTube channel. Winner will be randomly picked from one of the comments below this and other Mijia videos. Shipping is on me , customs and duties upon receipt by winner - if applicable - depending on where you live. Youtube, Facebook,... are not participating in this giveaway and therefore not responsible or liable. No cash disbursement and/or a replacement of the prizes is possible, recourse to the courts is not permitted.