pseudo code for adding audio to a video file

gistfile1.cpp

                    float audioDuration = (1.0/1000.0) * (float)(lastTimestampMillis-firstTimestampMillis);
                    
                    string audioCommands;
                    if( audioPath.length() ){
                        audioCommands = " -ss "+ofToString(timelineOffset, 3)+" -t " + ofToString(audioDuration, 3)+ " -i "+ ofToDataPath(audioPath, true);
                    }

                    string addAudio = ffmpeg + " -i "+ofToDataPath(savefile, false)+" "+ audioCommands +" -codec copy -shortest " +  ofToDataPath(ofFilePath::removeExt( savefile ) + "withAudio."  + ofFilePath::getFileExt(savefile), false);
            
                    system(addAudio.c_str());