Android: app crashes in background with media_kit (audio crackling then force-close)

[elias001011]

Description

When Sonora is playing music and the app goes to the background (screen off or another app in foreground), after 1-5 minutes the audio starts crackling/faltering and then the app crashes completely — losing the notification, the foreground service, and the entire queue state.

This does NOT happen with Musify (https://github.com/gokadzev/Musify), which uses the same audio_service structure but a different audio engine.

Version: 1.6.0+38
Device: Multiple Android devices tested

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Root Cause Analysis

After comparing Sonora's code with Musify's, the critical difference is in the audio playback engine:

Aspect	Sonora	Musify
Audio engine	media_kit (libmpv)	just_audio (ExoPlayer)
Native libs	media_kit_libs_video	❌ Not used
audio_service	✅ Yes	✅ Yes
androidStopForegroundOnPause	✅ false	✅ false

Why media_kit causes the crash

media_kit is a video-first library built on libmpv. On Android, even when used solely for audio playback (no VideoController), libmpv still:

1. Allocates native resources tied to the Flutter rendering surface
2. When the app goes to background, Android destroys/detaches this surface
3. libmpv keeps trying to decode without a valid surface → audio crackling
4. Native crash takes down the entire process (including the audio_service foreground service)

just_audio (used by Musify) doesn't have this problem because it uses Android's native ExoPlayer, which:

• Is audio-only — no rendering surface needed
• Handles audio focus correctly
• Is significantly lighter on memory
• Is designed for background playback from the ground up

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Steps to Reproduce

1. Install Sonora on any Android device (release build)
2. Start playing any song
3. Minimize the app or turn off the screen
4. Wait 1-5 minutes
5. Observed: audio starts crackling/faltering, then the app crashes

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Proposed Solutions

Option A (Recommended — definitive): Replace audio engine with just_audio

Keep media_kit_video exclusively for the video player widget (when the user watches a music video) and use just_audio for audio-only playback in SonoraAudioHandler.

Files that would need to change:

1. pubspec.yaml — Add just_audio and just_audio_background
2. lib/presentation/features/player/audio_handler.dart — Replace Player (media_kit) with AudioPlayer (just_audio)
3. lib/presentation/features/player/audio_equalizer_handler.dart — Adapt equalizer for just_audio
4. lib/presentation/providers/video_player_provider.dart — Keep media_kit_video isolated for video only

Option B (Quick mitigation — palliative): Reduce cache size + configure audio attributes

In audio_handler.dart, the current cache settings are very aggressive:

await playerPlatform.setProperty('demuxer-max-bytes', '104857600');  // 100MB
await playerPlatform.setProperty('demuxer-max-back-bytes', '52428800'); // 50MB

100MB cache is excessively large for a background audio app on resource-constrained Android devices. Reducing to:

await playerPlatform.setProperty('demuxer-max-bytes', '20971520');     // 20MB
await playerPlatform.setProperty('demuxer-max-back-bytes', '10485760'); // 10MB

And adding audio stream configuration to keep playback alive in background:

await playerPlatform.setProperty('audio-stream-silence', 'yes');

Option C: Offer a user-facing toggle in Settings

Add a "Background stability mode" toggle in Settings → Playback that:

• Reduces cache from 100MB → 20MB
• Disables heavy features (crossfade, lookahead preloading)
• Warns the user about potential trade-offs in transition smoothness

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Additional Notes

• androidStopForegroundOnPause is already false ✅
• AndroidManifest already has FOREGROUND_SERVICE, FOREGROUND_SERVICE_MEDIA_PLAYBACK, WAKE_LOCK ✅
• androidNotificationOngoing is false — setting it to true might help keep the service alive

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References

• media_kit background crash issue: [Android] Crash after backgrounding during video playback: FlutterJNI is not attached to native media-kit/media-kit#1289
• Audio background best practices: https://developer.android.com/media/media3/session/background-playback
• Musify (app with same audio_service structure but stable background playback): https://github.com/gokadzev/Musify

[gmstyle]

intresting...thanks for this feedback and for the solutions proposed, i use every day sonora with my pixel 7 pro and i don't have this issue so i need to investigate more to get a solution. but i have a question: did u have already disabled battery optimizations from sonora settings?

[elias001011]

intresting...thanks for this feedback and for the solutions proposed, i use every day sonora with my pixel 7 pro and i don't have this issue so i need to investigate more to get a solution. but i have a question: did u have already disabled battery optimizations from sonora settings?

Yes, I turned it off, but it wasn't enough. Later, I additionally performed an advanced procedure via adb and it seems to have resolved the issue.

[gmstyle]

i can't reproduce the issue with my pixel 7 pro. all works properly in background. But for now i can focus option B that could be a good optimization in all the cases

[gmstyle]

intresting...thanks for this feedback and for the solutions proposed, i use every day sonora with my pixel 7 pro and i don't have this issue so i need to investigate more to get a solution. but i have a question: did u have already disabled battery optimizations from sonora settings?

Yes, I turned it off, but it wasn't enough. Later, I additionally performed an advanced procedure via adb and it seems to have resolved the issue.

can you post here or describe the adb procedure you followed? thanks!

[elias001011]

Thanks a lot for such a detailed investigation, this is really helpful.

I think this is probably not so much an issue with Sonora itself, but more with how aggressive Android can be when killing heavier background processes. That said, I really appreciate any effort to make Sonora's playback lighter and more resilient, since that only helps regardless of the root cause.

On my end, I managed to fix (or at least significantly mitigate) this by running an ADB command to stop Android from killing the process:

adb shell dumpsys deviceidle whitelist 

This adds the app to the Doze whitelist, which prevents the system from applying background/standby restrictions to it. After doing this, the crash stopped happening (or at least didn't happen again in my testing).

I mention this because Android tends to be a lot more aggressive with heavier processes, and this issue never happened with just_audio, even without disabling Android's battery optimizations for it. That lines up with the root cause analysis above regarding media_kit/libmpv and native resource handling when the app goes to background.

[gmstyle]

Great. i'm investigating and i can optimize mpv (mediakit) resources by setting

await playerPlatform.setProperty('video', 'no')

programmativcally when an only audio or video is reproduced to allocate right resources for the player.

Also with the cache optimization i think we can improve performances on android.

But i want to investigate better

PS - switching to just_audio makes sonora only audio support without videos (initially sonora had only audio support and used just_audio)