How to enable aptX on Xiaomi Redmi Note 9 Pro: a complete guide with proven ways

Why aptX is important for your Redmi Note 9 Pro and what you need to know before setting up

Qualcomm’s aptX codec is an audio compression technology that significantly improves audio quality when wirelessly transmitted over Bluetooth. On Xiaomi Redmi Note 9 Pro (model joyeuse or excalibur, depending on the region), this codec can be disabled by default, despite hardware support. Unlike the standard SBC codec, which is limited to a bitrate of ~328 kbit / s, aptX provides a bitrate of 352-576 kbit / s with less latency – critical for listening to music in high resolution or watching video.

However, there are nuances: not all versions of the Redmi Note 9 Pro officially support aptX. For example, the global version (MIUI Global) is often deprived of this feature due to licensing restrictions, while Chinese firmware (MIUI China) can include it out of the box. In addition, aptX requires a compatible sound source (for example, headphones or a speaker with codec support) and the correct settings of the Bluetooth stack in the smartphone.

Before you start setting up, make sure that:

• 🔍 Your Redmi Note 9 Pro is equipped with a Snapdragon chipset 720G (Supports aptX hardware).
• 🎧 Your wireless headphones/columns are certified for aptX (check the device specifications).
• 📱 On the smartphone installed firmware is not older MIUI 12.5 (earlier versions may not have the right drivers).

Checking for aptX support on your Redmi Note 9 Pro

Before you try to turn on aptX, you need to confirm that your smartphone is capable of working with this codec at all, and there are two reliable methods for this: through the Engineer Mode (engineering menu) and using third-party applications.

Method 1: Engineering menu (works on most firmware):

1. Open the Phone app and type the combination: ##36446337## (or #4636## → select Phone Information).
2. Go to Bluetooth or Audio (the name may be different).
3. Check the Supported Codecs bar – if there is aptX or aptX HD, your smartphone supports the codec.

Method 2: Bluetooth Codec Info (from Google Play)

• 📱 Install the app and connect compatible headphones.
• 🔍 The main window will display the current codec used (for example, SBC, AAC or).
• ⚙️ If aptX is not listed, you need to manually activate it (more on that below).

Important: on some firmware, MIUI codec can be hidden even with hardware support, in which case only manual activation via ADB or modification of system files will help.

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If there is no Bluetooth section in the engineering menu, try using the MTK Engineering Mode app (for devices on Mediatek) or Qualcomm Service Menu (for Snapdragon).

Enable aptX through hidden Bluetooth settings (without root)

If your Redmi Note 9 Pro supports aptX but the codec doesn’t activate automatically, you can try enabling it through hidden Bluetooth stack settings.This method doesn’t require root rights, but requires a PC connection and ADB use.

Instructions:

Install ADB drivers on PC (download Minimal ADB and Fastboot)

Enable USB Debugging in Developer Settings → About Phone → MIUI Version (click 7 times) → Additional Settings → Developer

Connect your smartphone to your PC and confirm the debugging permission

Download the archive with bluetooth_config.xml (spoiler)

-->

Follow the instructions in ADB Shell:

adb shell


su




mount -o rw,remount /system




cp /sdcard/bluetooth_config.xml /system/etc/bluetooth/




chmod 644 /system/etc/bluetooth/bluetooth_config.xml




reboot

After the reboot:

1. Connect headphones with support for aptX.
2. Open Settings → Bluetooth and find the connected device.
3. Click on the icon. ⚙️ next to the headphone name and select Sound Quality or Codec.
4. The list should include aptX or aptX HD.

⚠️ Warning: Incorrect editing of system files can cause Bluetooth module to crash.Before changing, back up the original file bluetooth_config.xml Team: Adb pull /system/etc/bluetooth/bluetooth_config.xml

Activate aptX through build.prop modification (requires root)

If the previous method didn’t work and you have root rights, you can try enabling aptX through editing the build.prop file. This method is more risky, but often effective for firmware where the codec is blocked software.

Steps:

1. Install any file manager with root support (such as Root Explorer or Solid Explorer).
2. Go to /system/build.prop and open the file in the text editor.
3. Add the following lines to the end of the file: persist.bluetooth.a2dp_offload_cap=sbc-aac-aptx-aptxhd persist.bluetooth.a2dp_offload_enabled=true
4. Save the changes, set the rights to 644 and restart the smartphone.

After the reboot, check the available codecs through the Bluetooth Codec Info app. If aptX never came up, try adding a line as well:

persist.bluetooth.enable.aptx=true

⚠️ Warning: Changing build.prop can cause unstable system performance, especially if you use a custom kernel or unofficial firmware!

Problems and Solutions: Why AptX Doesn't Work on the Redmi Note 9 Pro

Even after all the manipulations, aptX may not be activated, and let's look at the typical causes and ways to eliminate them:

If none of these methods have worked, it is worth considering alternatives:

• 🔊 Use the codec. AAC — It is worse than AptX in terms of delays, but better. SBC quality.
• 🎵 Connect the headphones over the wire with an adapter USB-C → 3.5mm (e.g. Xiaomi Type-C to Audio Jack).
• 📱 Install firmware with support LDAC (For example, crDroid, if your headphones are compatible with this codec.

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On the Redmi Note 9 Pro with the Snapdragon 720G chipset, the aptX codec is hardware-supported, but its activation depends on the firmware. The best results come from custom builds based on Android 11+.

Custom firmware for full support for aptX

If standard methods don't work, the most reliable way to get an aptX is to install custom firmware. The Redmi Note 9 Pro has a good track record:

• 📱 Pixel Experience – pure Android with support for all Qualcomm codecs.
• 🔄 LineageOS – stable firmware with open source.
• ⚡ crDroid – Optimized build with advanced sound settings.
• 🎵 Havoc-OS – includes patches for improved Bluetooth audio performance.

Installation process:

1. Unlock the bootloader through Mi Unlock Tool (requires a Xiaomi account binding).
2. Install custom TWRP receivers for Redmi Note 9 Pro (version must match the model joyeuse/excalibur).
3. Download firmware (e.g. Pixel Experience) and GApps (if you need Google services).
4. Sweat through TWRP by running Wipe → Format Data (required!).

Once custom firmware is installed, aptX codec is usually activated automatically when compatible headphones are connected, and Bluetooth settings will allow you to manually select the codec.

⚠️ Note: Installing custom firmware will void the warranty and may result in data loss.Before firmware save a backup through TWRP (Backup → Also make sure the firmware version is compatible with your Redmi Note 9 Pro model (check the codename in Settings). → The phone. → Model).

Codec comparison: aptX vs AAC vs LDAC on Redmi Note 9 Pro

To see if you should bother with aptX setup at all, compare it to other popular codecs available on the Redmi Note 9 Pro:

From the table, it can be seen that aptX offers the best balance between sound quality and latency, making it the perfect choice for:

• 🎮 Games (minimizing the lag between video and sound).
• 🎧 Listening to music in high resolution (FLAC, WAV).
• 🎥 Watching movies (synchronizing sound with image).

However, if your headphones support LDAC and the firmware allows it to be activated, this codec will give you even higher sound quality (but with more latency and battery consumption).

FAQ: Frequent questions on aptX on Redmi Note 9 Pro