Replace fmod on Linux with SDL Audio or something similar

[slackmoehrle]

Users have stated that we are not truly open-source on Linux because we require fmod. This isn't free and they have no other options. During our weekly meeting @ricardoquesada suggested that we could offer SDL Audio as an alternative and let users turn on fmod if they choose to. @linshun agreed. The timing of this change is TBD.

@slackmoehrle is happy to test when ready.

[ricardoquesada]

yes, other alternatives are:

• use ALSA driver directly
• or use PulseAudio

[minggo]

Can refer to #16410. The PR use OpenAL for linux.

[JOOpdenhoevel]

I don't really know how powerful/fast/etc. those alternatives are, but from my point of view, OpenAL has a big advantage: It's a cross-platform library. The implementation for Windows only uses OpenAL, MPEG, and Vorbis, which are available for Windows as well as for Linux. Due to this fact, I could simply copy the source files and it worked. All tests were positive, the C++ test and the Lua test. Another option would be to merge those implementations into one which would make maintaining the engine way easier. I could do that for Linux and Windows if you like this idea.

[minggo]

@Janonard you are right. @dumganhar i think you can take a look too. I think it is better that we can use OpenAL as possible, then it is easy to main the codes.

[minggo]

Another option would be to merge those implementations into one which would make maintaining the engine way easier. I could do that for Linux and Windows if you like this idea.

Yep, it is better.

[dumganhar]

Agree this.

We only need OpenSLES for Android & OpenAL for other platforms. Easily maintaining our engine is really important.

BTW, we also need to improve New Audio Engine since I think the logic isn't very clear for developer to understand, we need to do more encapsulation, abstraction and documentation.

[chuckhacker]

OpenAL-soft has a OpenSLES driver built-in:

https://github.com/kcat/openal-soft/blob/2f1f7f4c6aaf54f9361865d508d82cdf027368bf/Alc/backends/opensl.c

[cirosantilli]

In particular, this blocks a Debian package from being created.

And creates problems that we can't solve properly because no source, e.g.:

• porting fmod: No arm linux fmod #18001
• binary file build option quirks: error while loading shared libraries: libfmod.so.6 in Debian #15137 (comment)

[v1993]

It also may create big problems with licensing target product.

[v1993]

Is there any progress in this direction?