change member variable to private

app/src/main/cpp/audio_player.cpp

@@ -311,10 +311,8 @@ AUDIO_PLAYER_FUNC(void, play, jstring input_jstr, jstring filter_jstr) {
 
             int nb_samples = frame->nb_samples < MAX_FFT_SIZE ? frame->nb_samples : MAX_FFT_SIZE;
             if (nb_samples >= MIN_FFT_SIZE) {
-                mVisualizer->fft_context->nb_samples = nb_samples;
-                memcpy(mVisualizer->fft_context->data, frame->data[0], nb_samples);
-                mVisualizer->fft_run();
-                fft_callback(env, thiz, fft_method, mVisualizer->fft_context->output, mVisualizer->fft_context->out_samples);
+                int8_t *output_data = mVisualizer->fft_run(frame->data[0], nb_samples);
+                fft_callback(env, thiz, fft_method, output_data, mVisualizer->getOutputSample());
             }
 
             ret = av_buffersrc_add_frame(audioSrcContext, frame);

app/src/main/cpp/visualizer/frank_visualizer.cpp

@@ -158,8 +158,10 @@ FrankVisualizer::~FrankVisualizer() {
     LOGE("FrankVisualizer release...");
 }
 
-void FrankVisualizer::fft_run() {
+int8_t* FrankVisualizer::fft_run(uint8_t *input_buffer, int nb_samples) {
     mFftLock.lock();
+    fft_context->nb_samples = nb_samples;
+    memcpy(fft_context->data, input_buffer, static_cast<size_t>(nb_samples));
     filter_sys_t *p_sys = fft_context;
 #ifdef FIXED_FFT
     fft_fixed(p_sys);
@@ -167,6 +169,14 @@ void FrankVisualizer::fft_run() {
     fft_float(p_sys);
 #endif
     mFftLock.unlock();
+    return fft_context->output;
+}
+
+int FrankVisualizer::getOutputSample() {
+    if (fft_context) {
+        return fft_context->out_samples;
+    }
+    return 0;
 }
 
 int FrankVisualizer::init_visualizer() {

app/src/main/cpp/visualizer/frank_visualizer.h

@@ -39,13 +39,15 @@ class FrankVisualizer {
 private:
     std::mutex mFftLock;
 
+    filter_sys_t *fft_context = nullptr;
+
 public:
     FrankVisualizer();
     ~FrankVisualizer();
 
-    filter_sys_t *fft_context = nullptr;
+    int getOutputSample();
 
-    void fft_run();
+    int8_t* fft_run(uint8_t *input_buffer, int nb_samples);
 
     int init_visualizer();
 

app/src/main/cpp/visualizer/frank_visualizer_jni.cpp

@@ -63,14 +63,12 @@ VISUALIZER_FUNC(int, nativeInitVisualizer) {
 VISUALIZER_FUNC(int, nativeCaptureData, jobject buffer, jint size) {
     if (!buffer) return -1;
     FrankVisualizer *mVisualizer = getCustomVisualizer(env, thiz);
-    if (!mVisualizer || !mVisualizer->fft_context) return -2;
+    if (!mVisualizer) return -2;
     int nb_samples = size < MAX_FFT_SIZE ? size : MAX_FFT_SIZE;
     if (nb_samples >= MIN_FFT_SIZE) {
-        mVisualizer->fft_context->nb_samples = nb_samples;
-        auto *direct_buffer = static_cast<uint8_t *>(env->GetDirectBufferAddress(buffer));
-        memcpy(mVisualizer->fft_context->data, direct_buffer, static_cast<size_t>(nb_samples));
-        mVisualizer->fft_run();
-        fft_callback(env, mVisualizer->fft_context->output, mVisualizer->fft_context->out_samples);
+        auto *input_buffer = static_cast<uint8_t *>(env->GetDirectBufferAddress(buffer));
+        int8_t *output_data = mVisualizer->fft_run(input_buffer, nb_samples);
+        fft_callback(env, output_data, mVisualizer->getOutputSample());
     }
     return 0;
 }