docker pull immortalwrt/opde:sdk
docker run -it --rm immortalwrt/opde:sdk zsh # or bash
export http_proxy= # [your proxy], do not use localhost or 127.0.0.1
export https_proxy=$http_proxy
opde feeds && opde config -a
make package/feeds/telephony/rtpengine/compile -j$(nproc) || make package/feeds/telephony/rtpengine/compile V=s

Applying ./patches/04-prevent-systemd-detection.patch using plaintext: 
patching file lib/lib.Makefile

Applying ./patches/05-use-spandsp3.patch using plaintext: 
patching file daemon/Makefile
make[4]: Entering directory '/openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module'
make -C /openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214 M=/openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module O=/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214 modules
make[5]: Entering directory '/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214'
make[6]: Entering directory '/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214'
  CC [M]  /openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module/xt_RTPENGINE.o
/openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module/xt_RTPENGINE.c: In function 'proc_control_read_write.isra.42':
/openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module/xt_RTPENGINE.c:3396:1: warning: the frame size of 1072 bytes is larger than 1024 bytes [-Wframe-larger-than=]
 }
 ^
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module/xt_RTPENGINE.mod.o
  LD [M]  /openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module/xt_RTPENGINE.ko
/openwrt/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/bin/aarch64-openwrt-linux-musl-ld: cannot open linker script file /openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214/arch/arm64/kernel/module.lds: No such file or directory
make[7]: *** [/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214/scripts/Makefile.modpost:129: /openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module/xt_RTPENGINE.ko] Error 1
make[6]: *** [/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214/Makefile:1548: modules] Error 2
make[6]: Leaving directory '/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214'
make[5]: *** [Makefile:146: sub-make] Error 2
make[5]: Leaving directory '/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-bcm27xx_bcm2710/linux-4.19.214'
make[4]: *** [Makefile:34: modules] Error 2
make[4]: Leaving directory '/openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/kernel-module'
make[3]: *** [Makefile:286: /openwrt/build_dir/target-aarch64_cortex-a53_musl/rtpengine-transcode/rtpengine-mr9.5.2.1/.built] Error 2