ViPERFX_RE

A reverse-engineered, modernized port of ViPER4Android. The DSP has been re-implemented from a decompilation of the original libv4a_fx.so, with audio processed in float32, dead code removed, and dependencies refreshed.

If you want ViPER on desktop instead of Android, see:

• ViPER4Windows
• ViPER4Mac

Module Architecture

ViPERFX_RE ships as two separate Magisk modules, both built around the same DSP engine (ViPERDSP) but integrated through different Android audio HAL interfaces. They are not interchangeable: each module is designed for a specific generation of Android’s audio framework. Installing the wrong one may either do nothing or cause boot issues.

Non-AIDL (Legacy) Module

The non-AIDL module uses the classic Android audio effect plugin interface (often informally referred to as the “HIDL-based” path due to its association with the older audio HAL stack).

• Why it no longer works on Android 15+: Google has migrated the audio effect framework from the legacy C-based plugin model to a stable AIDL HAL implementation. Devices launching with Android 15 no longer support loading effect_handle_t plugins, as the old framework path has been removed entirely. See AIDL for HALs for more details.

AIDL Module

The AIDL module implements the modern audio effect HAL introduced in Android 13, which became the only officially supported audio effect path for devices launching with Android 15 and later.

Which module should you install?

Run the following command:

adb shell ps -A | grep "audio.*aidl"

If your see any process related to audio HAL with "aidl" in the name, you need the AIDL module. If not, the non-AIDL module should work.

Disclaimers

• Tested hardware is narrow. Non-AIDL is confirmed on Pixel 8 Pro / Android 14. AIDL is confirmed on Pixel 8 Pro / Android 16. Other devices may bootloop, may need vendor-specific shims (e.g. ShadoV's PIXAML for AIDL on some Pixels), or may simply do nothing. Make a backup before flashing.
• Audio fidelity is best-effort. The DSP is decompiled from libv4a_fx.so. Subtle deviations from the original ViPER4Android are expected. If you spot one, please open a PR — the source is here precisely so it can be improved.
• Not for commercial use. This is a reverse-engineering project and may carry legal restrictions in your jurisdiction. Use at your own risk.

Installation

1. Download the module zip matching your Android version (see the table above) from the Releases page, and the ViPER4Android app.
2. Flash the Magisk module. Do not flash both modules.
3. Install the app.
4. Reboot. Open the app and verify effects are applied (use any of the diagnostic commands below to confirm).

AIDL Driver Troubleshooting

Log Tags

Driver	Tag	Level
AIDL	ViPER4Android_AIDL	I/W/E
AIDL	ViPER4Android	D/I/E
AIDL	AHAL_EffectImpl	D/I/V/E
AIDL	AHAL_EffectContext	E
AIDL	AHAL_EffectThread	V

1. Check if the library is loaded

adb logcat -s 'ViPER4Android_AIDL:*' 'ViPER4Android:*' | grep -E 'Welcome|viperLibrary|created'

Expected:

ViPER4Android_AIDL: ViperAidlEffect created
ViPER4Android: Welcome to ViPER FX
ViPER4Android: Current version is 1.x.x (202xxxxx)

If missing, the audio framework never loaded the .so. Verify the config XML was patched:

adb shell cat /vendor/etc/audio_effects_config.xml | grep v4a

Expected:

<library name="v4a_aidl" path="libv4a_aidl.so"/>
<effect name="v4a_standard_aidl" library="v4a_aidl" uuid="90380da3-..." type="7261676f-..."/>

And verify the SELinux label on the library itself:

adb shell su -c 'ls -Z /vendor/lib64/soundfx/libv4a_*.so'

Expected:

u:object_r:vendor_file:s0 /vendor/lib64/soundfx/libv4a_aidl.so

2. Check if SHM files exist and have correct permissions

adb shell ls -laZ /data/local/tmp/v4a/

Expected:

-rw-rw-rw- 1 audioserver audio u:object_r:shell_data_file:s0   32784 ... shm_hp.bin
-rw-rw-rw- 1 audioserver audio u:object_r:shell_data_file:s0   32784 ... shm_spk.bin
-rw-rw-rw- 1 audioserver audio u:object_r:shell_data_file:s0     256 ... shm_status.bin

Inspect SHM header (magic number check):

adb shell xxd -l 16 /data/local/tmp/v4a/shm_status.bin

Expected:

00000000: 534d 3456 0300 0000 0100 0000 0100 0000  SM4V............

3. Check SELinux denials

adb logcat -d -s audit | grep v4a
# or, broader:
adb logcat -d | grep -E 'avc.*denied.*(v4a|shm|shell_data_file)'

If you see avc: denied lines naming the HAL process and the SHM files, the live policy injection from post-fs-data.sh did not stick. This is the single most common cause of "module installs cleanly but audio is unprocessed."

4. Dump audioserver effect list

adb shell dumpsys media.audio_flinger | grep -E -B2 -A10 'Effect ID|ViPER|v4a|90380da3'

Expected (effect loaded on session xxx):

  Effect ID xxx:
    Session State Registered Internal Enabled Suspended:
    00000   002   y          n        y       n
    Descriptor:
    - UUID: 90380da3-8536-4744-a6a3-5731970e640f
    - TYPE: 7261676f-6d75-7369-6364-28e2fd3ac39e
    - name: ViPER4Android
    - implementor: ViPER520 / RE Team

5. Filter by audio HAL process

# Find the audio HAL process name (device-specific)
adb shell ps -A | grep audio

Expected (Pixel 8 Pro):

audioserver   1044     1  ...  S android.hardware.audio.service-aidl.aoc
audioserver   1107     1  ...  S audioserver

Then filter logcat by the HAL PID:

adb logcat --pid=$(adb shell pidof android.hardware.audio.service-aidl.aoc | tr -d '\r') -s 'ViPER4Android_AIDL:*' 'ViPER4Android:*'

Note that the process name is device-specific.

Building

Prerequisites: Android NDK, CMake, Make. Set ANDROID_NDK_HOME (or ANDROID_NDK_ROOT).

make libs   # build libv4a_re.so for arm64-v8a and armeabi-v7a
make zip    # build + package a flashable Magisk module zip

Credits

• Zhuhang and ViPER520 — original ViPER4Android.
• Martmists, Iscle, llsl — reverse-engineering of the DSP.