x264 requires nasm (tested in fedora29)
Just tried to build gstreamer without libx264, thus this port was cloned and compiled. But got a lot of linking errors because of missing symbols. For example:
home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:576: undefined reference to `x264_10_predict_16x16_v_sse'
/usr/bin/ld: /home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:576: undefined reference to `x264_10_pixel_sad_16x16_sse2'
/usr/bin/ld: /home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:576: undefined reference to `x264_10_predict_16x16_h_sse2'
/usr/bin/ld: /home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:576: undefined reference to `x264_10_pixel_sad_16x16_sse2'
/usr/bin/ld: /home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:576: undefined reference to `x264_10_predict_16x16_dc_sse2'
/usr/bin/ld: /home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:576: undefined reference to `x264_10_pixel_sad_16x16_sse2'
/usr/bin/ld: libx264-10.a(common_pixel.c.o): in function `intra_sad_x3_8x8c_ssse3':
/home/ceyusa/gst/gst-build/subprojects/x264/build/../common/pixel.c:577: undefined reference to `x264_10_predict_8x8c_dc_sse2'
I installed nasm and the problem got fixed :)
I'm not sure what the real fix could be, perhaps making nasm required for linux environments.