feat: reduce buffers to 1024

app/src/main/cpp/MixingPlayer.h

@@ -55,6 +55,8 @@ public:
         return (int32_t) result;
     }
 
+    int getRate() { return kSampleRate; }
+
     // Call this from Activity onPause()
     void stopAudio() {
         // Stop, close and delete in case not already closed.

app/src/main/cpp/PlaybackEngine.cpp

@@ -82,7 +82,8 @@ PlaybackEngine::PlaybackEngine(std::string filesDir, int resid):
     exitMusicFeedThread(false),
     android_fd(0),
     haveTimeRatio(false),
-    timeRatio(1.0)
+    timeRatio(1.0),
+    playbackRate(48000)
 {
     LOGI("PlaybackEngine()");
     LOGI("NDK LOG_LEVEL=%d", LOG_LEVEL);
@@ -92,6 +93,7 @@ PlaybackEngine::PlaybackEngine(std::string filesDir, int resid):
     LOGI("read_mp3() is_ok=%d", is_ok);
     mPlayer = new MixingPlayer(samples);
     int32_t res = mPlayer->startAudio();
+    playbackRate = mPlayer->getRate();
     LOGI("startAudio() = %d", res);
     initRubberBand();
 }
@@ -150,15 +152,14 @@ void PlaybackEngine::closeMusicFile() {
 }
 
 void PlaybackEngine::musicFeedThread() {
-    // refactor: rename to 'num_buf_samples'
-    size_t num_pad = 48000; // hack! how much to actually reserve? is getPreferredStartPad() always < getSamplesRequired()?
-    size_t buf_stride = num_pad;
-    float* buf = (float*) malloc(num_pad*2*sizeof(float));
-    float* buf_ptr[] {buf, buf + num_pad};
-    memset(buf, 0, num_pad*2*sizeof(float));
-    unsigned char* cbuf = (unsigned char*) malloc(num_pad*2*sizeof(int16_t));
-    memset(cbuf, 0, num_pad*2*sizeof(int16_t));
-    size_t cbuf_size_bytes = num_pad*2*sizeof(int16_t);
+    size_t num_buf_samples = buf_size_samples;
+    size_t buf_stride = num_buf_samples;
+    float* buf = (float*) malloc(num_buf_samples * 2 * sizeof(float));
+    float* buf_ptr[] {buf, buf + num_buf_samples};
+    memset(buf, 0, num_buf_samples * 2 * sizeof(float));
+    unsigned char* cbuf = (unsigned char*) malloc(num_buf_samples * 2 * sizeof(int16_t));
+    memset(cbuf, 0, num_buf_samples * 2 * sizeof(int16_t));
+    size_t cbuf_size_bytes = num_buf_samples * 2 * sizeof(int16_t);
 
     int idebug = 0;
 
@@ -185,8 +186,8 @@ void PlaybackEngine::musicFeedThread() {
             continue;
         }
 
-        if (num_samples > num_pad) {
-            LOGE("wanted %d samples but buf is only %d samples", num_samples, num_pad);
+        if (num_samples > num_buf_samples) {
+            LOGE("wanted %d samples but buf is only %d samples", num_samples, num_buf_samples);
             continue;
         }
 
@@ -226,7 +227,8 @@ void PlaybackEngine::musicFeedThread() {
         }
 
         size_t num_decoded_samples = done / sizeof(int16_t) / 2; // 2 channels - TODO: actually use mp3 channels!! below, too. 2.
-        LOGI("num_decoded_samples = %d", num_decoded_samples);
+        //LOGD("num_decoded_samples = %d", num_decoded_samples);
+
         // convert interleaved int16 to de-interleaved float [-1.0, 1.0] format
         for(size_t i = 0; i < num_decoded_samples; i++) {
             for(size_t j = 0; j < 2; j++) {
@@ -234,7 +236,7 @@ void PlaybackEngine::musicFeedThread() {
             }
         }
 
-        LOGI("calling stretcher.process()");
+        //LOGD("calling stretcher.process()");
         stretcher.process(buf_ptr, num_decoded_samples, false);
     }
 }
@@ -253,35 +255,23 @@ void PlaybackEngine::playBeat() {
 
 void PlaybackEngine::playMusic(int fd) {
     if(!mPlayer) return;
-    // TODO: fetch sampling rate from mp3 file, and use librubberband to correct for it
-    // MixingPlayer::kSampleRate (48000)
-    // mp3->rate
-
-    // feed samples to librubberband
-    // fetch resamples out of librubberband
-
-    //if(mPlayer) mPlayer->playMusic();
-    // TODO: fd is opened; dispose of fd when stopping or being discarded ...
     LOGI("PlaybackEngine::playMusic(fd=%d)", fd);
-    //close(fd); // for now, nothing is implemented. we just close it again.
-    // we will use mp3file_open_fd() later.
-
     android_fd = fd;
     musicFile.reset(mp3file_open_fd(android_fd, 0));
     if(musicFile) {
-        timeRatio = ((double) 48000) / ((double) musicFile->rate);
+        timeRatio = ((double) playbackRate) / ((double) musicFile->rate);
         haveTimeRatio.store(true);
     }
     haveMusicFile.store(true);
-    mPlayer->setMusic(std::make_shared<MusicProvider>(&stretcher));
+    mPlayer->setMusic(std::make_shared<MusicProvider>(&stretcher, buf_size_samples));
 }
 
-MusicProvider::MusicProvider(RubberBand::RubberBandStretcher *stretcher) : stretcher(stretcher), idebug(0) {
-    // refactor: rename to 'num_buf_samples'
-    // TODO: for cache-friendliness, it would be better to have smaller 'num_buf_samples'
-    // hack! how much to actually reserve? is getPreferredStartPad() always < getSamplesRequired()?
-    //size_t buf_stride = num_pad;
-    buf = (float*) malloc(num_buf_samples*2*sizeof(float));
+MusicProvider::MusicProvider(RubberBand::RubberBandStretcher *stretcher, size_t buf_size_samples) :
+    stretcher(stretcher),
+    idebug(0),
+    buf_size_samples(buf_size_samples)
+{
+    buf = (float*) malloc(buf_size_samples*2*sizeof(float));
     //float* buf_ptr[] {buf, buf + num_pad};
 }
 
@@ -296,8 +286,8 @@ void MusicProvider::onAudioReady(float *data, int32_t frames) {
     }
 
     // 1. read from oboe into our temp de-interleaved buffer 'buf'
-    size_t num_frames = std::min((size_t) frames, num_buf_samples);
-    float* buf_ptr[] {buf, buf + num_buf_samples};
+    size_t num_frames = std::min((size_t) frames, buf_size_samples);
+    float* buf_ptr[] {buf, buf + buf_size_samples};
     stretcher->retrieve(buf_ptr, num_frames);
 
     // 2. convert to add samples to interleaved *data

app/src/main/cpp/PlaybackEngine.h

@@ -18,16 +18,16 @@
 /** Provides music through a regular callback to oboe. Called from separate oboe thread. */
 class MusicProvider : public AudioCallbackProvider {
 public:
-    explicit MusicProvider(RubberBand::RubberBandStretcher *stretcher);
+    explicit MusicProvider(RubberBand::RubberBandStretcher *stretcher, size_t buf_size_samples);
     ~MusicProvider() override;
 
     /** Called from separate oboe thread. */
     void onAudioReady(float *data, int32_t frames) override;
 private:
-    const size_t num_buf_samples = 48000;
     RubberBand::RubberBandStretcher *stretcher;
     float *buf;
     int idebug;
+    size_t buf_size_samples;
 };
 
 class PlaybackEngine : public StepListener {
@@ -48,6 +48,8 @@ private:
     int android_fd;
     std::atomic<bool> haveTimeRatio;
     double timeRatio;
+    int playbackRate;
+    static size_t constexpr buf_size_samples = 1024;
     void initRubberBand();
     void closeRubberBand();
     void closeMusicFile();