EMSCRIPTEN - RuntimeError: operation does not support unaligned accesses

[MichealReed]

Hey @mackron long time, hope all is well! I'm working on a PR DaniilAlpha/minisound#6 here to add recorder and generator support and on wasm, I see RuntimeError: operation does not support unaligned accesses. This appears to only happen some of the time when trying to play with multiple engines. You can find all the build files in the minisound_ffi/src folder of that PR.

The reproduction in Flutter Web:

• Start the app.
• Engine#1 initializes, loads a sound, and starts on the device.
• Engine#2 and Engine#3 initialize but do not start.
• Start then stop recording.
• Click Play sound. (Engine#1)
• Results in RuntimeError: operation does not support unaligned accesses.
• Recording and waves continue to work. (Engine#2 and Engine#3)
• Engine#1 when attempting to play the loaded sound continues to face the unaligned accesses error.

The recorder loads a sound the same way, but the engine keeps working without issue.

I can probably work around this with better handling of multiple engines in engine.c but wanted to let you know there might be an alignment issue with wasm, maybe a race condition with device?

Let me know what you think.

[MichealReed]

"It only happens (was happen) ones the engine initialized a sound"

according to the original creator, so seems after one engine plays a sound the others cannot on emscripten but this is not true for WASAPI.

[mackron]

Is there any additional information to narrow it down a bit? Hard to know exactly what's causing it. How are the sounds and engines being allocated?

On an unrelated note, the fact that you have more than one ma_engine is extremely unusual. I highly doubt having multiple engine's is causing this specific issue, but typically a program would have only a single ma_engine object. What's the rationale for having multiple engines?

[MichealReed]

Is there any additional information to narrow it down a bit? Hard to know exactly what's causing it. How are the sounds and engines being allocated?

On an unrelated note, the fact that you have more than one ma_engine is extremely unusual. I highly doubt having multiple engine's is causing this specific issue, but typically a program would have only a single ma_engine object. What's the rationale for having multiple engines?

It probably will not be needed and the only reason I discovered this is from an example. We have the engine, recorder, and generator as separate objects and in the example we spawn all three. Not pressing at all, will allow the main engine to be passed via constructor for our uses.