Piano: sound stutters under Android 10

[scheunengeist]

Hi! First off, thanks for this app, it's a really nice helper tool for musical needs on the go.

Issue:

• After upgrading to Android 10 (LineageOS 17.1), the piano is not really usable anymore due to strong sound stuttering. Notes also seem slightly delayed.
• I experience no issues playing sound from other sources (e. g. videos and music (both mp3 and flac) through VLC, music through the regular AOSP player).
• The problem didn't occur under Andoid 9 (LineageOS 16.0) using the same version of Semitone, where the keyboard was responsive and the sound was quite clear.

Device: Samsung Galaxy S5 System: LineageOS 17.1 (Android 10) Semitone: 1.3 from F-Droid (seems to only require one permission (microphone), which is granted)

I couldn't find any relevant info on the web, and there doesn't seem a similar issue here on github. Can anyone confirm this, and/or provide a hint how to solve it? Thanks!

[scheunengeist]

Having read a bit more, it was suggested somewhere that latency issues may be caused by battery optimizations. Tested: turning off battery optimization for Semitone -> no effect. Additionally increasing performance profile to highest level (most performance, least power saving) -> no effect.

[somebelse]

I have this problem as well.

I just found out, when there is already a source playing audio, when opening the app, the stuttering is gone. The other media source can be turned off and the problem stays fixed as long as Semitone isn't closed. Tonality has the same Problem for me and the same workaround works.

Semitone 1.3 (Google Playstore) Tonality 1.2 (Google Playstore)

Motorola Moto G8 plus running Android 10

Android security patch level October 1, 2021

Google Play system update 2021-11-01 Q

baseband version M6125_43.45.03.48R DOHA_ROWNDSDS_CUST

kernel version 4.14.117-perf+

1 Wed Sep 29 03:14:30 CDT 2021

build number QPIS30.28-Q3-28-26-4-1-7

[somebelse]

Rotating the keyboard while no other audio is present resets the workaround, so that it stutters again

[somebelse]

You can also start the workaround while playing audio and then rotating the keyboard

[benrg]

I've reproduced this on two devices, one running Android 10 (stock) and the other Android 9 (Lineage). It happens with both the piano and the metronome, and with both the synthesized and mp3 piano modes.

The audio output of one device looks like this:

i.e., alternating 20 ms of audio and 20 ms of silence. The output of the other is 20 ms of audio and 4 ms of silence.

The Oboe library uses AAudio as a backend by default with OpenSLES as a fallback. This problem seems to be specific to AAudio. The reason it showed up in a 9-to-10 upgrade in the original report may be that LineageOS 16 didn't have AAudio, or it failed to initialize for some reason. The reason it can be worked around by opening the app while playing other audio may be that that also prevents AAudio from initializing.

You could work around it by adding asb.setAudioApi(oboe::AudioApi::OpenSLES); to PianoEngine::init(), though I suppose it would be better to fix whatever is keeping AAudio from working. I looked through the code and see no obvious bugs.