I’m working on an Android app for pitch shifting and have encountered some challenges. Initially, I tried using Superpowered, but I ran into issues with sound distortion when changing the pitch. Now, I’m attempting to build and use the Rubber Band library for Android. However, the provided examples are quite outdated, and I’ve also explored other third-party open-source examples without much success—they’re either unmaintained or based on very old code.

I’m new to working with native code in Android, so I might be missing something fundamental. Could someone please guide me step-by-step on how to integrate the Rubber Band library into my Android app?

Here is the link to the Rubber Band library I’m trying to build: Github Link.

I attempted to build the .mk file using the ndk-build command, but since the reference is quite outdated, I encountered numerous errors. Additionally, the Rubber Band library has undergone many updates since then, which might be contributing to the issues.
Here is android.mk file which i am using.

LOCAL_PATH := $(call my-dir)/..
LOCAL_MODULE := rubberband
LOCAL_MODULE_FILENAME := librubberband-jni

RUBBERBAND_PATH := $(LOCAL_PATH)
RUBBERBAND_SRC_PATH := $(RUBBERBAND_PATH)/src

LOCAL_C_INCLUDES := $(LOCAL_PATH) $(LOCAL_PATH)/src

LOCAL_CFLAGS := 
    -Wall 
    -I$(RUBBERBAND_PATH) 
    -I$(RUBBERBAND_SRC_PATH) 
    -DUSE_SPEEX 
    -DUSE_KISSFFT 
    -DPROCESS_SAMPLE_TYPE=float 
    -DLACK_POSIX_MEMALIGN 
    -DUSE_OWN_ALIGNED_MALLOC 
    -DLACK_SINCOS 
    -DNO_EXCEPTIONS 
    -DNO_THREADING 
    -DNO_THREAD_CHECKS

RUBBERBAND_JNI_FILES := 
    $(RUBBERBAND_SRC_PATH)/jni/RubberBandStretcherJNI.cpp

RUBBERBAND_SRC_FILES := 
        $(RUBBERBAND_SRC_PATH)/base/Profiler.cpp 
        $(RUBBERBAND_SRC_PATH)/system/Thread.cpp 
        $(RUBBERBAND_SRC_PATH)/system/Allocators.cpp 
        $(RUBBERBAND_SRC_PATH)/system/sysutils.cpp 
        $(RUBBERBAND_SRC_PATH)/system/VectorOpsComplex.cpp 
        $(RUBBERBAND_SRC_PATH)/StretcherChannelData.cpp 
        $(RUBBERBAND_SRC_PATH)/dsp/AudioCurveCalculator.cpp 
        $(RUBBERBAND_SRC_PATH)/dsp/FFT.cpp 
        $(RUBBERBAND_SRC_PATH)/dsp/Resampler.cpp 
        $(RUBBERBAND_SRC_PATH)/audiocurves/SilentAudioCurve.cpp 
        $(RUBBERBAND_SRC_PATH)/audiocurves/CompoundAudioCurve.cpp 
        $(RUBBERBAND_SRC_PATH)/audiocurves/HighFrequencyAudioCurve.cpp 
        $(RUBBERBAND_SRC_PATH)/audiocurves/SpectralDifferenceAudioCurve.cpp 
        $(RUBBERBAND_SRC_PATH)/audiocurves/ConstantAudioCurve.cpp 
        $(RUBBERBAND_SRC_PATH)/audiocurves/PercussiveAudioCurve.cpp 
        $(RUBBERBAND_SRC_PATH)/StretcherImpl.cpp 
        $(RUBBERBAND_SRC_PATH)/StretcherProcess.cpp 
        $(RUBBERBAND_SRC_PATH)/StretchCalculator.cpp 
        $(RUBBERBAND_SRC_PATH)/RubberBandStretcher.cpp 
        $(RUBBERBAND_SRC_PATH)/speex/resample.c

LOCAL_SRC_FILES += 
    $(RUBBERBAND_JNI_FILES) 
        $(RUBBERBAND_SRC_FILES)

LOCAL_SRC_FILES += 
    $(RUBBERBAND_SRC_PATH)/kissfft/kiss_fft.c 
    $(RUBBERBAND_SRC_PATH)/kissfft/kiss_fftr.c

ifeq ($(TARGET_ARCH_ABI), x86_64)
LOCAL_CFLAGS += 
    -O3 
    -DUSE_POMMIER_MATHFUN 
    -DNO_TIMING 
    -DNO_TIMING_COMPLETE_NOOP

endif

ifeq ($(TARGET_ARCH_ABI), arm64-v8a)
LOCAL_CFLAGS += 
    -O3 
    -DUSE_POMMIER_MATHFUN 
    -DNO_TIMING 
    -DNO_TIMING_COMPLETE_NOOP

endif

ifeq ($(TARGET_ARCH_ABI), armeabi-v7a)
LOCAL_CFLAGS += 
    -O3 
    -mfpu=neon 
    -mfloat-abi=softfp 
    -ffast-math 
    -ftree-vectorize 
    -freciprocal-math 
    -fsingle-precision-constant 
    -D__ARM_ARCH_7__ 
    -DARM_RUNFAST 
    -DUSE_POMMIER_MATHFUN 
    -DNO_TIMING 
    -DNO_TIMING_COMPLETE_NOOP

LOCAL_ARM_MODE := arm
LOCAL_ARM_NEON := true
endif

ifeq ($(TARGET_ARCH_ABI), armeabi)
LOCAL_CFLAGS += 
    -O3 
    -DNO_TIMING 
    -DNO_TIMING_COMPLETE_NOOP

LOCAL_ARM_MODE := arm
LOCAL_ARM_NEON := false
endif

LOCAL_LDLIBS += -llog

include $(BUILD_SHARED_LIBRARY)