lockstep/TODO.md

## 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`

O> 16 KB paging for NDK libs
* target SDK level 35

* record the accelero and check why repeated fast beats result in occasional detection outages
    - guess: the threshold gets pushed so high that the later beats are not detected properly
    - maybe we need the `*0.6` factor after all (but verify this!)

* minimum amplitude for accelero (avoid detecting e.g. when phone is lying flat and you hammer on the table)
* filter away bad SQI areas of the signal (do not detect steps if we have bad SQI)

## Nice-To
* myband PlaybackEngine.cpp has latency management and other audio performance related features.
  Check if the app can be improved (audio wise) by using that code instead.

* Sampling rate for accelerometer - do we need to measure actual sensor FPS, or is it stable 50 Hz?

* re-calculate IIR filter coefficients. probably not critical for 50 Hz vs. 60 Hz.

* re-visit sampling rate and channel count.
  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