AudioWorklet can't initialize when mainScriptUrlOrBlob is a blob

[JoeOsborn]

If Module["mainScriptUrlOrBlob"] is set to a Blob, the call to AudioWorklet.addModule() on line 214 of libwebaudio.js passes the blob in as the argument, which stringifies the blob into [object Blob], which is then treated as a relative URL.

I have a workaround by using URL.createObjectURL, but the real fix would be to at least detect this error and ideally to check the type of mainScriptUrlOrBlob and call URL.createObjectURL if necessary.

[sbc100]

Is this a regression or has this always been a limitation of AUDIO_WORKLET?

[JoeOsborn]

I’m not sure, this is the first time I’ve tried to use AudioWorklet with mainScriptUrlOrBlob as a blob. The analogous change in libpthread was to check if the mainScriptUrlOrBlob was set, and if so (and if it was a blob) to use URL.createObjectURL.

I wonder if some other worklet scenarios have the same issue?

[sbc100]

I certainly seems logical to use the same pattern for both pthreads and wasm workers / audio worklets.

[JoeOsborn]

As an aside, something like the WASM_WORKERS=2 setting could be useful for audio worklets too.

[sbc100]

Hopefully we can completely do away with the need for the separate .ww.js file like we did already for pthreads.

[sbc100]

I started work on this in #24163