[Help] Cross compile movit (shotcut & mlt GPU deps), which can build on-device

[knyipab]

movit, which enables the GPU mode of shotcut, seems to require on device compilation (successful on device build shown in this TUR PR). When building the package, it executes a compiled binary to generate .cpp file (see the error log of this cross compile attempt). However, there does not seem to be on device build feature in thistermux-packages repo, right?

If termux-packages does not accpet on-device built package, there seems to be only four options:

1. Someone figure out how to cross-compile movit
2. Workaround to bring ondevice built packages to termux-packages
3. Give up and disable the movit GPU mode for shotcut and any mlt-dependent pacakges
4. Put movit, shotcut (and possibly mlt) to TUR

May I seek advice from the community? Thanks.

[Biswa96]

Yes, it may be possible to build with host program. Shotcut could be added here instead of TUR.

[TomJo2000]

1. Is definitely the preferred option.

2. I'm very reluctant to consider.
   Building packages on-device is a last resort, and generally only acceptable for "simple" packages

3. If 1 doesn't work out I think this would be the preferred (interim) solution

4. That is always an option if the standard build infrastructure doesn't fit for shotcut.

[knyipab]

If someone want to try option 1, may continue the work at PR #20352.

I will do option 3 for now. But fyi, there are still some issues regarding the shotcut package and I will open issue later.

[TomJo2000]

Bingo, found the issue.
The make_bundled_shaders helper binary is of course compiled for the target architecture.
Thus it can't be run during the build, but the build tries to run it.
Now if I can just find where it builds it...

Line 188 in Makefile.in is where it's getting called to do its thing.

bundled_shaders.cpp: make_bundled_shaders $(SHADERS) # L:187
	./make_bundled_shaders $(SHADERS) > $@       # L:188

The make rule for it is just above.

# A program to compile all the shaders into one bundle that we can link into the library.        # L:183
MAKE_BUNDLE_OBJS=make_bundled_shaders.o util.o init.o resource_pool.o                            # L:184
make_bundled_shaders: $(MAKE_BUNDLE_OBJS)                                                        # L:185
    $(LIBTOOL) --mode=link $(CXX) $(LDFLAGS) -o make_bundled_shaders $(MAKE_BUNDLE_OBJS) -lepoxy # L:186

We should be able to patch this part to build the helper binary for the host architecture instead.

[TomJo2000]

So, in theory yes.
In practice I've not sure how to get it to build make_bundled_shaders such that it can be run by the build system as a native executable (as opposed to the cross compilation target of the rest of the package)

[Biswa96]

For building make_bundled_shaders program, the host environment need eigen package.

[TomJo2000]

Hmm