Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [x] I looked for a similar issue and couldn't find any.
- [x] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [x] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/


Hi,

I'd like some helpm on linking a file which i am calling form a cusotm filter I'm trying to build:

I managed to call a `.o` from my filter by adding some flags to the compiler, but upon pulling changes I erased it and can't find how to get a shared `.o` to work witjh my custom filter, :(.

I'm using `ubuntu 20.04`, `gcc 8.4.0` and gpac up tp date with the master branch - so this [commit](https://github.com/gpac/gpac/commit/206ad0907cc1f56ef031b5e3b1e30136e721ba9f) -.

I've got my Makefile which is heavily inspired by the [dec_openhevc](https://github.com/gpac/gpac/blob/master/modules/dec_openhevc/Makefile), as it is module a filter.

My command to compile my filter into a library file is :
```sh
COMMAND = @gcc  -shared -o ../../bin/gcc/gf_libTest.so ../../src/filters/ff_common.o read_test.o  -lm -L/usr/local/lib -L/usr/local/lib -lavcodec -lavformat -lavutil -lavdevice -lswscale -lswresample -lavfilter -fsanitize=address -Wl,-z,defs -dynamiclib -L../../bin/gcc -lgpac -ldl  -fsanitize=address -Wl,-z,defs -dynamiclib 
```
which gives me an error :
```sh
/usr/bin/ld: ../../src/filters/ff_common.o: in function `ffmpeg_register_free':
ff_common.c:(.text+0xe7): undefined reference to `gf_fs_remove_filter_register'
/usr/bin/ld: ../../src/filters/ff_common.o: in function `ffmpeg_build_register':
ff_common.c:(.text+0x18a3): undefined reference to `gf_fs_add_filter_register'
/usr/bin/ld: ff_common.c:(.text+0x1a92): undefined reference to `gf_fs_add_filter_register'
/usr/bin/ld: ../../src/filters/ff_common.o: in function `ffmpeg_report_options':
ff_common.c:(.text+0x23ea): undefined reference to `gf_filter_report_meta_option'
collect2: error: ld returned 1 exit status
```

Any pointer?


Thks,

P
[Help wanted] Linkage with internal functions in custom filter
This is a GitHub Issue
repo:gpac
owner:gpac
Title : [Help wanted] Linkage with internal functions in custom filter
Issue date:

--- start body ---
Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [x] I looked for a similar issue and couldn't find any.
- [x] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [x] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/


Hi,

I'd like some helpm on linking a file which i am calling form a cusotm filter I'm trying to build:

I managed to call a `.o` from my filter by adding some flags to the compiler, but upon pulling changes I erased it and can't find how to get a shared `.o` to work witjh my custom filter, :(.

I'm using `ubuntu 20.04`, `gcc 8.4.0` and gpac up tp date with the master branch - so this [commit](https://github.com/gpac/gpac/commit/206ad0907cc1f56ef031b5e3b1e30136e721ba9f) -.

I've got my Makefile which is heavily inspired by the [dec_openhevc](https://github.com/gpac/gpac/blob/master/modules/dec_openhevc/Makefile), as it is module a filter.

My command to compile my filter into a library file is :
```sh
COMMAND = @gcc  -shared -o ../../bin/gcc/gf_libTest.so ../../src/filters/ff_common.o read_test.o  -lm -L/usr/local/lib -L/usr/local/lib -lavcodec -lavformat -lavutil -lavdevice -lswscale -lswresample -lavfilter -fsanitize=address -Wl,-z,defs -dynamiclib -L../../bin/gcc -lgpac -ldl  -fsanitize=address -Wl,-z,defs -dynamiclib 
```
which gives me an error :
```sh
/usr/bin/ld: ../../src/filters/ff_common.o: in function `ffmpeg_register_free':
ff_common.c:(.text+0xe7): undefined reference to `gf_fs_remove_filter_register'
/usr/bin/ld: ../../src/filters/ff_common.o: in function `ffmpeg_build_register':
ff_common.c:(.text+0x18a3): undefined reference to `gf_fs_add_filter_register'
/usr/bin/ld: ff_common.c:(.text+0x1a92): undefined reference to `gf_fs_add_filter_register'
/usr/bin/ld: ../../src/filters/ff_common.o: in function `ffmpeg_report_options':
ff_common.c:(.text+0x23ea): undefined reference to `gf_filter_report_meta_option'
collect2: error: ld returned 1 exit status
```

Any pointer?


Thks,

P
--- end body ---
