docs

app/src/main/cpp/PlaybackEngine.cpp

@@ -54,7 +54,6 @@ static bool read_mp3(std::string filename, std::vector<float>& samples) {
     return ok1 && ok2;
 }
 
-
 struct RbLogger : public RubberBand::RubberBandStretcher::Logger {
     virtual void log(const char *s) {
         LOGI("%s", s);
@@ -83,6 +82,8 @@ PlaybackEngine::PlaybackEngine(std::string filesDir, int resid):
     android_fd(0),
     haveTimeRatio(false),
     timeRatio(1.0),
+
+    // these 3 values are preliminary -- will be set from MixingPlayer defaults in the ctor body below
     playbackRate(48000),
     numOutChannels(2),
     numInChannels(2)
@@ -90,21 +91,27 @@ PlaybackEngine::PlaybackEngine(std::string filesDir, int resid):
     LOGI("PlaybackEngine()");
     LOGI("NDK LOG_LEVEL=%d", LOG_LEVEL);
     // NDK LOG_LEVEL=3  (DEBUG)
+
+    // load "bump" sound effect
     std::vector<float> samples;
     bool is_ok = read_mp3(mFilesDir + "/" + std::to_string(resid) + ".mp3", samples);
-    LOGI("read_mp3() is_ok=%d", is_ok);
+    LOGI("read_mp3() for bump effect, is_ok=%d", is_ok);
+
     mPlayer = new MixingPlayer(samples);
     int32_t res = mPlayer->startAudio();
     playbackRate.store(mPlayer->getRate());
     numOutChannels.store(mPlayer->getNumChannels());
     LOGI("startAudio() = %d rate=%d channels=%d", res, playbackRate.load(), numOutChannels.load());
+
+    // configure stretcher and start musicFeedThread()
     initRubberBand();
 }
 
 void PlaybackEngine::initRubberBand() {
-    // TODO: check mp3 actual sample rate, and adapt to 48000 Hz playback here
+    // we do not yet have a music file with actual sampling rate, so set the default ratio
     stretcher.setTimeRatio(1.0);
     stretcher.setPitchScale(1.0);
+
     stretcher.setDebugLevel(1); // 1: errors only. generally 0..4
 
     // feed samples into 'stretcher' and read bogus output