feat: play music through librubberband

TODO.md

@@ -1,5 +1,20 @@
 ## TODO
 
+* analyze the (secondly or so) noise beeps in the mp3 playback
+  - introduced with this commit
+  - is it librubberband, my failure to feed it properly (buffer exhaustion), or sth else?
+
+* correct sampling rate of libmpg123 vs. 48000 Hz using librubberband
+
+* record accelero and write recording to file
+
+* set feedForDelay in musicFeedThread() in PlaybackEngine.cpp
+  -  LOGI("feed %d silence samples", num_samples);
+  - set the sleep delay
+  - ideally, set the buf size
+* check playback buf size, and reduce buffer sizes
+  - LOGI("onAudioReady() frames=%d", frames);
+
 * reduce lib size, librubberband is 1.3 M (one .so file)
     - maybe we are compiling too many source files
     - # TODO: see Android.mk in librubberband and copy options from `LOCAL_CFLAGS`
@@ -26,6 +41,13 @@ O> 16 KB paging for NDK libs
   MixingPlayer currently forces both to 48000 and 2 respectively,
   regardless of what Android says would be optimal.
 
+* nice-to nice-to: ramp up audio pipelines twice - once to collect params, another one to use those
+
+## Technical Debt
+
+* remove duplication of `mp3file_open()` in `mp3file_open_fd()`
+* malloc() nullptr result handling
+
 ## Before release
 
 * check librubberband license