Hi FMOD team,
I am investigating a native FMOD crash in our Unity game and would like some guidance on whether this points to incorrect DSP / bus ChannelGroup lifecycle usage on our side, a known issue, or something worth investigating further.
Environment
- Unity: 6000.3.12f1
- FMOD version: 2.03.12
- Platform: Windows x64, Mac
- Scripting backend: Mono
- Crash reproduced with both on Windows:
- fmodstudio.dll
- fmodstudioL.dll in a Development Build
The crash appears to be the same in both the regular and logging DLL. We are seeing a native write access violation on the FMOD mixer thread. It is not isolated to a few devices but happens for testers as well as developers, it crashes in the editor and in the built game.
The repeated crash signature is:
Access violation - code c0000005 AV.Type: Write Failure.Bucket: INVALID_POINTER_WRITE_c0000005_fmodstudio.dll!Unknown Faulting module: fmodstudio.dll / fmodstudioL.dll Thread: FMOD mixer thread
We attach custom DSP capture nodes to several FMOD Studio bus ChannelGroups in order to visualize the audio output from those buses. When the related in-game app or visualization is closed, we remove and clean up the corresponding DSP connection.
The crash appears in a specific sequence where two separate gameplay scenarios create and later clean up these DSP captures. After both scenarios have completed, leaving the game idle for around 20–30 minutes eventually triggers the crash. It is not fully deterministic yet, but it currently reproduces in roughly one out of three attempts.
I tried to reproduce this in a smaller clean example, but I have not been able to make that crash so far. At the moment it seems specific to our real usage pattern.
I saw this in the logs as well that may be a hint of whats wrong?
[FMOD] Bus channel group for 'bus:/Music/ApplicationSource/Assembly' was not ready (ERR_STUDIO_NOT_LOADED). Retrying.
[FMOD] Created audio capture DSP (instance 1) for bus: bus:/Music/ApplicationSource/Assembly [FMOD] Successfully initialized audio capture
[FMOD] Destroyed capture for 'bus:/Music/ApplicationSource/Assembly' (no more consumers)
[FMOD] EventInstance::update : Event {8287fc98-05b4-4312-a122-82ae8bcf3c14} has waited 10.0 seconds for DSP graph to go idle - check for plugins that may be keeping it active
The event GUID corresponds to an outro/video event with nested content and a long reverb tail, so perhaps this is also something that could cause problems as it keeps the event perhaps longer active?
I have gathered 2 full crash dumps, one with the fmodstudio.dll and one with the fmodstudioL.dll ~2-3 gb each that could share privately where I hope may would be helpful in the search of the issue as you perhaps can make more out of these as I.
Thanks in advance
Savas