Dear all: I enable opengl and opengl es by #define 'PJMEDIA_VIDEO_DEV_HAS_OPENGL 1' & '#define PJMEDIA_VIDEO_DEV_HAS_OPENGL_ES 1'. When I compiler pjmedia/src/pjmedia-vidodev/opengl_dev.c, it show error message, as shown in the below: ===================== /root/usr_lib/source/pjsip_2.4.5/pjmedia/lib/libpjmedia-videodev-armv7l-unknown-linux-gnueabihf.a(opengl_dev.o): In function `opengl_factory_init': opengl_dev.c:(.text+0xe6): undefined reference to `pjmedia_vid_dev_opengl_imp_get_cap' /root/usr_lib/source/pjsip_2.4.5/pjmedia/lib/libpjmedia-videodev-armv7l-unknown-linux-gnueabihf.a(opengl_dev.o): In function `opengl_factory_create_stream': opengl_dev.c:(.text+0x1d6): undefined reference to `pjmedia_vid_dev_opengl_imp_create_stream' ===================== The 'pjmedia_vid_dev_opengl_imp_get_cap' and 'pjmedia_vid_dev_opengl_imp_create_stream' function is define at pjmedia/src/pjmedia-videodev/android_opengl.c, but my platform is linux. How can I do ? Please give me some advice, thanks. Best Regards. Raiden