[sumo-user] FFmpeg version

[Jakob Haahr Taankvist <jht@xxxxxxxxxxxxx>]

Hi all

When compiling sumo on Arch Linux (e.g. the version from AUR) cmake 
searches for a suitable ffmpeg version and I get the warning:

-- Unsuitable FFmpeg version found #define FFMPEG_VERSION "n4.1.3"

The error originates from here:

In the file build/cmake_modules/FindFFMPEG.cmake ll. 221-223

    string(REGEX REPLACE ".*#define FFMPEG_VERSION[ \t]+\"([0-9\.]+).*" 
"\\1" FFMPEG_VERSION "${_version_line}")
    if("${FFMPEG_VERSION}" VERSION_LESS "3.4")
        message(STATUS "Unsuitable FFmpeg version found ${FFMPEG_VERSION}")

Basically the issue is that the version found includes the 'n' and the 
cmake script does not expect that.

I have tested on two Arch Linux systems and it is a problem on both. On 
Ubuntu the ffmpeg version is 3.4 (without the 'n') so there is no problem.

I see that they use the 'n's here 
https://git.ffmpeg.org/gitweb/ffmpeg.git so maybe that is where it is 
coming from.

Clearly an easy fix would be to just put 'n?'  at the right place in the 
regex, but maybe there is a better way?

Best Regards Jakob