setComplexVideoFilter with unexpected results with filtergraph about ffmpeg-cli-wrapper

[igracia]

@bramp Could this be related with #76?

[igracia]

More failed tests with similar results

• [1:0]adelay=10000[t1];[t1]amix=inputs=1 (remove the pipe |)
• [1:0]adelay=10000[t1],[t1]amix=inputs=1 (replace the semicolon ;)

The last filter would allow us to run from the command line as ffmpeg -y -v error -i video.trk -i audio.trk -filter_complex [1:0]adelay=10000[t1],[t1]amix=inputs=1 -c:v copy out.webm, but both produce wrong output when run from a Java program.

[igracia]

It seems like it is related to how ProcessBuilder handles those args, and the fact that certain args have to be escaped. I've managed to get it working with this workaround

ffmpeg = new ProcessBuilder(
                    new String[] { "/bin/sh", "-c", "/usr/local/bin/ffmpeg " + argsStr })
                            .redirectErrorStream(true).start();

Not sure the "/bin/sh" , "-c" is something you want to have there. Should I upload a PR?

[igracia]

@bramp Would you accept a pull request with this modification?

[bramp]

There are a lot of Windows users of this library, so I wouldn't want to put a Linux specific fix in place. I will accept pull requests to fix this in a generic way.

[bramp]

I just read more about the failings in how java handles character escaping. http://bugs.java.com/view_bug.do?bug_id=6468220 and http://bugs.java.com/view_bug.do?bug_id=6518827

It might be worth using https://commons.apache.org/proper/commons-exec/index.html instead of the process builder. Happy to accept that pull request.