Dolby Digital Plus Fixed.
You just need to install it, you don't need to install anything, I fixed the errors in the original version of one you on youtube do

Auto_Brightness_Fix_v5
For Android 9

Auto_Brightness_Fix_v5b(20)
For Android 10

Auto_Brightness_Fix_v5b(rev)
For Android 10

Auto_Brightness_Fix_v5b(40)
For Android 10

Auto_Brightness_Fix_v5b(60)
For Android 10

Screen refresh rate (Pie-Q) For Mi9 v3.6.1

Update 09-12-2019
Pie: 60Hz, 66Hz, 69Hz, 72Hz, 75Hz, 78Hz, 84Hz, 90Hz
Q: 60Hz, 66Hz, 69Hz, 72Hz, 75Hz, 78Hz, 84Hz, 90Hz
*From 69Hz to 90Hz, flicker prevention mode must be enabled

Optimize touch sensitivity

Status bar two lines version V9.12.5Eu for Mi9

Dual Speaker Audio Mod
Version 9.12:
- Update for firmware base 9.12.5

Update 11-12-2019
Device support:
Q: K20, K20Pro, Mi9t, Mi9tPro, Mi9, MI8Se, MI9Lite(MICC9), MI9Se, MiMix3

P: MICC9e, MiNote10(MICC9Pro), Note7Pro

P&Q: 60Hz, 66Hz, 69Hz, 72Hz, 75Hz, 78Hz, 84Hz, 90Hz

*Update: Mi9t, Mi9tPro
*Source file from Len.

Update 14-12-2019 (9.12.12Eu)

Device support: Mi9(cepheus), K20Pro(raphael)

Pie: 60Hz, 66Hz, 69Hz, 72Hz, 75Hz, 78Hz, 84Hz, 90Hz

Q: 60Hz, 66Hz, 69Hz, 72Hz, 75Hz, 78Hz, 84Hz, 90Hz

*From 69Hz to 90Hz, flicker prevention mode must be enabled

Dual Speaker Audio Mod
Version 9.12:
- Update for firmware base 9.12.12

Mod Optimal For Mi9
Version 3.2:
- Improve stability

Evira Miui_Q 1.3
Upstreamed to 4.14.158
-Merge LA.UM.8.1.r1-12600-sm8150.0 by CAF
-Pixel schedutil governor
-Alucardsched governor
-Adreeno Boost
-Gps Optimization
-Increase scheduler settings