Return C++14 support

[nlimbani]

I am trying to compile the latest uvgRTP library on the ubuntu, but it is failing , following is the error

[ 18%] Building CXX object CMakeFiles/uvgrtp.dir/src/reception_flow.cc.o
/home/platform/rtp_stacks/uvgRTP/uvgRTP-master/src/reception_flow.cc: In member function \u2018rtp_error_t uvgrtp::reception_flow::install_receive_hook(void*, void ()(void, uvgrtp::frame::rtp_frame*), uint32_t)\u2019:
/home/platform/rtp_stacks/uvgRTP/uvgRTP-master/src/reception_flow.cc:207:45: error: could not convert \u2018{arg, hook}\u2019 from \u2018\u2019 to \u2018uvgrtp::receive_pkt_hook\u2019
receive_pkt_hook new_hook = { arg, hook };
^
/home/platform/rtp_stacks/uvgRTP/uvgRTP-master/src/reception_flow.cc: In member function \u2018int uvgrtp::reception_flow::clear_stream_from_flow(std::shared_ptr<std::atomic >)\u2019:
/home/platform/rtp_stacks/uvgRTP/uvgRTP-master/src/reception_flow.cc:728:5: error: \u2018scoped_lock\u2019 is not a member of \u2018std\u2019
std::scoped_lock hlg(hooks_mutex_, handlers_mutex_);
^
/home/platform/rtp_stacks/uvgRTP/uvgRTP-master/src/reception_flow.cc: In member function \u2018rtp_error_t uvgrtp::reception_flow::update_remote_ssrc(uint32_t, uint32_t)\u2019:
/home/platform/rtp_stacks/uvgRTP/uvgRTP-master/src/reception_flow.cc:744:5: error: \u2018scoped_lock\u2019 is not a member of \u2018std\u2019
std::scoped_lock hlg(hooks_mutex_, handlers_mutex_);
^
CMakeFiles/uvgrtp.dir/build.make:153: recipe for target 'CMakeFiles/uvgrtp.dir/src/reception_flow.cc.o' failed
make[2]: *** [CMakeFiles/uvgrtp.dir/src/reception_flow.cc.o] Error 1
CMakeFiles/Makefile2:72: recipe for target 'CMakeFiles/uvgrtp.dir/all' failed
make[1]: *** [CMakeFiles/uvgrtp.dir/all] Error 2
Makefile:151: recipe for target 'all' failed
make: *** [all] Error 2

[nlimbani]

When I ran "cmake .." I have following output.

xyz@ubuntu1604:/rtp_stacks/cmake-3.14.0-Linux-x86_64$ cmake --version
cmake version 3.14.0
xyz@ubuntu1604:/rtp_stacks/uvgRTP/uvgRTP-master/build$ cmake ..
-- The CXX compiler identification is GNU 5.4.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for C++ include pthread.h
-- Looking for C++ include pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Check if compiler accepts -pthread
-- Check if compiler accepts -pthread - yes
-- Found Threads: TRUE
-- Found Git: /usr/bin/git (found version "2.7.4")
-- The C compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Found Python: /usr/bin/python3.5 (found version "3.5.2") found components: Interpreter
fatal: Not a git repository (or any of the parent directories): .git
-- Failed to get git hash
-- No build type selected. Selecting Release. You may use CMAKE_BUILD_TYPE to select a different build type.
-- Looking for getrandom
-- Looking for getrandom - not found
-- Looking for sendmsg
-- Looking for sendmsg - found
-- Looking for sendmmsg
-- Looking for sendmmsg - found
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1")
PKG_CONFIG_PATH is not set. Setting it to lib/pkgconfig
libcrypto++ not found. Encryption will be disabled
-- Configuring done
-- Generating done
-- Build files have been written to: /home/xyz/rtp_stacks/uvgRTP/uvgRTP-master/build

[jrsnen]

Hi.

Thank you for submitting this. The issue seems to be that some newer code in uvgRTP requires C++17 support. You can submit a pr that fixes this, upgrade your compiler or wait that someone fixes this, but it may take a while as it is not a high priority for us to keep old C++ version supported.

BR, Joni

[danfe]

Here's is the patch I'm using to build uvgRTP in C++14 mode with GCC 4.9.4 I'm confined to. It also revealed some discrepancies in the code like missing #include <atomic> in src/rtcp_reader.hh and inconsistent ssrc argument in rtcp() constructors (<std::atomic<std::uint32_t>> vs. <std::atomic_uint>). Other issues are minor, e.g. my old GCC does not like aggregate initializations, incorrect return type for std::make_pair(flow, socket), etc.

[jrsnen]

@danfe Do you want to do a PR? I can also make the fixes. A previous research assistant mistakenly used c++17, so the issue is not widespread.

BR, Joni