Issue compiling emscripten library (SOLVED)

dapetcu21 · August 24, 2017, 8:52pm

Hi. I’m having some issues compiling libs with emscripten for a html5 native extension.

I’m trying to compile libwebm and apparently the symbol names differ. Running strings on the lib I compiled with emscripten yields _ZN9mkvparser10EBMLHeaderC2Ev, while the game seems to link against _ZN9mkvparser10EBMLHeaderC1Ev.

Is there a recommended way for compiling emstripten libraries for use with Defold? Any recommended emscripten version? flags?

Update: Apparently strings botched up. I did a regular grep through the .a file and apparently both symbols show up, which is correct. Now, question is, why isn’t my library linked with the extension? I placed an emscripten-compiled libwebm.a in lib/js-web. Is that correct?

dapetcu21 · August 24, 2017, 5:08pm

I eventually managed to compile it. I had to use emscripten 1.30.0

@Mathias_Westerdahl The good news is that I ported the video player extension to the web. The bad news is that it’s crazy slow.

I made a pull request

Ivan_Lytkin · May 2, 2022, 8:39am

Lot of time passed, but still we need to recompile libs for html build.

How did you manage to compile libwebm?
I tried emcmake cmake /path/to -G Xcode

that gives me an Xcode project, but result of building with xcodebuild doesn’t work -
lot of undefined symbols like __ZNK9mkvparser5Track10GetCodecIdEv

Maybe it’s problem with libvpx? My binary of libvpx.a is about 2MB and the only target I managed to build was “generic-gnu”

Mathias_Westerdahl · May 2, 2022, 8:42am

You can probably keep it a lot simpler if ju just use your own command line script.
E.g. look at our way of building the required library we used in our old extension:

github.com

defold/extension-videoplayer/blob/master/videoplayer/utils/webm/build_osx.sh


# put this in libvpx/third_party/libwbm and cd there

function terminate_usage {
	echo "USAGE: ./build_osx.sh <arch>"
	exit 1
}

ARCH="${1:-}" && [ ! -z "${ARCH}" ] || terminate_usage

if [ "$ARCH" == "x86_64" ]
then
	ARCH_FLAGS="-arch $ARCH -m64"
else
	# i386
	if [ "$ARCH" == "i386" ]
	then
		ARCH_FLAGS="-arch $ARCH -m32"
	else
		echo Unknown arch: $ARCH

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Unfortunately it doesn’t seem we saved the script for building with emscripten, but I suspect it should work pretty much the same, just with a different compiler etc.

Ivan_Lytkin · May 8, 2022, 12:18pm

Unfortunately OSX build file is not working anymore, there is an issue with missing libstdc (no more in Xcode?)

With current libs - it works in editor but can’t bundle OSX.
After I recompiled libs on my mac - it’s not working neither in editor nor bundle

Any help from people familiar with compiling this libs are appreciated.
@dapetcu21