WebRTC: Support ARM Environment Compilation

[sevenzoe]

On Ubuntu, cross-compile SRS using Docker.
There were issues with cross-compiling for ARM on the develop branch, but cross-compiling for ARM on the release4.0 branch was successful.

Please describe the issue you encountered.

1. SRS version: develop version
2. The log of SRS is as follows:
   arm-linux-gnueabihf-g++ -o objs/srs objs/src/core/srs_core.o objs/src/core/srs_core_version4.o objs/src/core/srs_core_autofree.o objs/src/core/srs_core_performance.o objs/src/core/srs_core_mem_watch.o objs/src/core/srs_core_time.o objs/src/kernel/srs_kernel_error.o objs/src/kernel/srs_kernel_log.o objs/src/kernel/srs_kernel_buffer.o objs/src/kernel/srs_kernel_utility.o objs/src/kernel/srs_kernel_flv.o objs/src/kernel/srs_kernel_codec.o objs/src/kernel/srs_kernel_io.o objs/src/kernel/srs_kernel_consts.o objs/src/kernel/srs_kernel_aac.o objs/src/kernel/srs_kernel_mp3.o objs/src/kernel/srs_kernel_ts.o objs/src/kernel/srs_kernel_stream.o objs/src/kernel/srs_kernel_balance.o objs/src/kernel/srs_kernel_mp4.o objs/src/kernel/srs_kernel_file.o objs/src/kernel/srs_kernel_rtp.o objs/src/protocol/srs_protocol_amf0.o objs/src/protocol/srs_protocol_io.o objs/src/protocol/srs_rtmp_stack.o objs/src/protocol/srs_rtmp_handshake.o objs/src/protocol/srs_protocol_utility.o objs/src/protocol/srs_rtmp_msg_array.o objs/src/protocol/srs_protocol_stream.o objs/src/protocol/srs_raw_avc.o objs/src/protocol/srs_rtsp_stack.o objs/src/protocol/srs_sip_stack.o objs/src/protocol/srs_http_stack.o objs/src/protocol/srs_protocol_kbps.o objs/src/protocol/srs_protocol_json.o objs/src/protocol/srs_protocol_format.o objs/src/protocol/srs_stun_stack.o objs/src/service/srs_service_log.o objs/src/service/srs_service_st.o objs/src/service/srs_service_http_client.o objs/src/service/srs_service_http_conn.o objs/src/service/srs_service_rtmp_conn.o objs/src/service/srs_service_utility.o objs/src/service/srs_service_conn.o objs/src/app/srs_app_server.o objs/src/app/srs_app_conn.o objs/src/app/srs_app_rtmp_conn.o objs/src/app/srs_app_source.o objs/src/app/srs_app_refer.o objs/src/app/srs_app_hls.o objs/src/app/srs_app_forward.o objs/src/app/srs_app_encoder.o objs/src/app/srs_app_http_stream.o objs/src/app/srs_app_thread.o objs/src/app/srs_app_bandwidth.o objs/src/app/srs_app_st.o objs/src/app/srs_app_log.o objs/src/app/srs_app_config.o objs/src/app/srs_app_pithy_print.o objs/src/app/srs_app_reload.o objs/src/app/srs_app_http_api.o objs/src/app/srs_app_http_conn.o objs/src/app/srs_app_http_hooks.o objs/src/app/srs_app_ingest.o objs/src/app/srs_app_ffmpeg.o objs/src/app/srs_app_utility.o objs/src/app/srs_app_edge.o objs/src/app/srs_app_heartbeat.o objs/src/app/srs_app_empty.o objs/src/app/srs_app_http_client.o objs/src/app/srs_app_http_static.o objs/src/app/srs_app_recv_thread.o objs/src/app/srs_app_security.o objs/src/app/srs_app_statistic.o objs/src/app/srs_app_hds.o objs/src/app/srs_app_mpegts_udp.o objs/src/app/srs_app_rtsp.o objs/src/app/srs_app_listener.o objs/src/app/srs_app_async_call.o objs/src/app/srs_app_caster_flv.o objs/src/app/srs_app_process.o objs/src/app/srs_app_ng_exec.o objs/src/app/srs_app_hourglass.o objs/src/app/srs_app_dash.o objs/src/app/srs_app_fragment.o objs/src/app/srs_app_dvr.o objs/src/app/srs_app_coworkers.o objs/src/app/srs_app_hybrid.o objs/src/app/srs_app_rtc.o objs/src/app/srs_app_rtc_conn.o objs/src/app/srs_app_dtls.o objs/src/app/srs_app_audio_recode.o objs/src/app/srs_app_sdp.o objs/src/main/srs_main_server.o objs/st/libst.a objs/openssl/lib/libssl.a objs/openssl/lib/libcrypto.a objs/ffmpeg/lib/libavcodec.a objs/ffmpeg/lib/libswresample.a objs/ffmpeg/lib/libavutil.a objs/opus/lib/libopus.a objs/srtp2/lib/libsrtp2.a -ldl -lpthread -static
   objs/ffmpeg/lib/libavcodec.a: error adding symbols: File format not recognized
   collect2: error: ld returned 1 exit status
   objs/Makefile:519: recipe for target 'objs/srs' failed
   make[2]: *** [objs/srs] Error 1
   make[2]: Leaving directory '/tmp/srs/trunk'
   Makefile:82: recipe for target 'server' failed
   make[1]: *** [server] Error 2
   make[1]: Leaving directory '/tmp/srs/trunk'
   Makefile:10: recipe for target 'default' failed
   make: *** [default] Error 2

**Replay**

**How to replay bug?**

> Steps to reproduce the bug

1. get  code

git clone https://github.com/ossrs/srs.git && cd srs
git checkout remotes/origin/develop



2. get docker

sudo docker pull registry.cn-hangzhou.aliyuncs.com/ossrs/srs:ubuntu16



3. enter docker

sudo docker run -it -v `pwd`:/tmp/srs -w /tmp/srs/trunk registry.cn-hangzhou.aliyuncs.com/ossrs/srs:ubuntu16 bash



4. install the toolchain

apt-get install -y gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf
apt-get install -y --force-yes nasm



5. build

./configure --arm --static --cc=arm-linux-gnueabihf-gcc --cxx=arm-linux-gnueabihf-g++ --ar=arm-linux-gnueabihf-ar --ld=arm-linux-gnueabihf-ld --randlib=arm-linux-gnueabihf-randlib && make

**Expect**

> Expected behavior

**Please describe your expectation**

> Describe what you expect to happen

`TRANS_BY_GPT3`

[sevenzoe]

I don't know if it's a problem with my environment.

lsb_release -a :

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.3 LTS
Release: 16.04
Codename: xenial

uname -a :

Linux ydx-desktop 4.15.0-88-generic #88~16.04.1-Ubuntu SMP Wed Feb 12 04:19:15 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

TRANS_BY_GPT3

[winlinvip]

I will make the change to automatically disable RTC during cross-compilation.
Also, I suggest you use 3.0 release instead of develop as it is prone to issues.

TRANS_BY_GPT3

[sevenzoe]

I want an ARM version of SRS with WebRTC functionality, author, do you have any methods or ideas to solve it?

TRANS_BY_GPT3

[winlinvip]

In theory, it can be done by specifying the cross-compiler when compiling FFMPEG.

TRANS_BY_GPT3

[winlinvip]

@sevenzoe Can you handle it yourself?

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[sevenzoe]

@winlinvip Yourself? Not much confidence, author.

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[winlinvip]

./configure --cc=xxx-cc sets the variable SRS_TOOL_CC by externally specifying the compiler. This variable can be specified during compilation, for example, st is:

make  CC=${SRS_TOOL_CC}

If you can't figure it out, just wait and see if someone more skilled comes along.

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[sevenzoe]

@winlinvip Hmm, wait a moment, I believe it's possible, author-sama

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[liuguang]

Switch to 608f3d0 and apply the patch attached.
git am 0001-fix-for-cross-build-with-arm-on-ubuntu16.patch
cd srs/trunk
./configure --arm --static --cc=arm-linux-gnueabihf-gcc --cxx=arm-linux-gnueabihf-g++ --ar=arm-linux-gnueabihf-ar --ld=arm-linux-gnueabihf-ld --randlib=arm-linux-gnueabihf-randlib && make

It can be cross-compiled on Ubuntu 16.
0001-fix-for-cross-build-with-arm-on-ubuntu16.zip

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[winlinvip]

@liuguang 👍 I will find time to look at this patch and see if it can be merged.

TRANS_BY_GPT3

[winlinvip]

Fixed

For cross-compiling:
Make sure to maintain the markdown structure.

• openssl is a platform-specific tool:
  Make sure to maintain the markdown structure.

./Configure linux-armv4 linux-aarch64

• libsrtp and libopus are host-specific:
  Make sure to maintain the markdown structure.

--host=HOST       cross-compile to build programs to run on HOST [BUILD]

• FFmpeg is parameters and prefix:
  Make sure to maintain the markdown structure.

  --arch=ARCH              select architecture [arm, aarch64]
  --enable-cross-compile   assume a cross-compiler is used
  --target-os=OS           compiler targets OS []
  --cross-prefix=PREFIX    use PREFIX for compilation tools []

Usage:

• https://github.com/ossrs/srs/wiki/v4_CN_SrsLinuxArm#ubuntu-cross-build-srs-armv8aarch64
• https://github.com/ossrs/srs/wiki/v4_EN_SrsLinuxArm#ubuntu-cross-build-srs-armv8aarch64
• https://github.com/ossrs/srs/wiki/v4_CN_SrsLinuxArm#ubuntu-cross-build-srs-armv7
• https://github.com/ossrs/srs/wiki/v4_EN_SrsLinuxArm#ubuntu-cross-build-srs-armv7

root@c19bb908f5aa:/srs# uname -a
Linux c19bb908f5aa 5.10.25-linuxkit #1 SMP Tue Mar 23 09:27:39 UTC 2021 armv7l armv7l armv7l GNU/Linux
root@c19bb908f5aa:/srs# 
root@c19bb908f5aa:/srs# 
root@c19bb908f5aa:/srs# ldd objs/srs
	libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0xfe7ae000)
	libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0xfe78a000)
	librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0xfe774000)
	libstdc++.so.6 => /usr/lib/arm-linux-gnueabihf/libstdc++.so.6 (0xfe661000)
	libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0xfe5e9000)
	libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xfe5c0000)
	libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xfe4d2000)
	/lib/ld-linux-armhf.so.3 (0xfefc7000)
root@c19bb908f5aa:/srs# 
root@c19bb908f5aa:/srs# ./objs/srs -v
4.0.128
root@c19bb908f5aa:/srs# 

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