What is ffmpeg java wrapper?

In this java application, I am trying to convert a video into small clips.

Here is the implementation class for the same

package ffmpeg.clip.process;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.file.Paths;
import java.time.Duration;
import java.time.LocalTime;
import java.time.temporal.ChronoUnit;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.stream.Collectors;
import ffmpeg.clip.utils.VideoConstant;
import ffmpeg.clip.utils.VideoUtils;
/*
 * @author Nitishkumar Singh
 * @Description: class will use ffmpeg to break an source video into clips
 */
public class VideoToClip {
    /*
     * Prevent from creating instance
     */
    private VideoToClip() {
    }
    /**
     * Get Video Duration is milliseconds
     * 
     * @Exception IOException - File does not exist VideoException- Video File have data issues
     */
    static LocalTime getDuration(String sourceVideoFile) throws Exception {
        if (!Paths.get(sourceVideoFile).toFile().exists())
            throw new Exception("File does not exist!!");
        Process proc = new ProcessBuilder(VideoConstant.SHELL, VideoConstant.SHELL_COMMAND_STRING_ARGUMENT,
                String.format(VideoConstant.DURATION_COMMAND, sourceVideoFile)).start();
        boolean error Occurred = (new BufferedReader(new InputStreamReader(proc.getErrorStream())).lines()
                .count() > VideoConstant.ZERO);
        String durationInSeconds = new BufferedReader(new InputStreamReader(proc.getInputStream())).lines()
                .collect(Collectors.joining(System.lineSeparator()));
        proc.destroy();
        if (error Occurred || (durationInSeconds.length() == VideoConstant.ZERO))
            throw new Exception("Video File have some issues!");
        else
            return VideoUtils.parseHourMinuteSecondMillisecondFormat(durationInSeconds);
    }
    /**
     * Create Clips for Video Using Start and End Second
     * 
     * @Exception IOException - Clip Creation Process Failed InterruptedException - Clip Creation task get's failed
     */
    static String toClipProcess(String sourceVideo, String outputDirectory, LocalTime start, LocalTime end,
            String fileExtension) throws IOException, InterruptedException, ExecutionException {
        String clipName = String.format(VideoConstant.CLIP_FILE_NAME,
                VideoUtils.getHourMinuteSecondMillisecondFormat(start),
                VideoUtils.getHourMinuteSecondMillisecondFormat(end), fileExtension);
        String command = String.format(VideoConstant.FFMPEG_OUTPUT_COMMAND, sourceVideo,
                VideoUtils.getHourMinuteSecondMillisecondFormat(start),
                VideoUtils.getHourMinuteSecondMillisecondFormat(end.minus(start.toNanoOfDay(), ChronoUnit.NANOS)),
                outputDirectory, clipName);
        LocalTime startTime = LocalTime.now();
        System.out.println("Clip Name: " + clipName);
        System.out.println("FFMPEG Process Execution Started");
        CompletableFuture completableFuture = CompletableFuture.supplyAsync(() -> {
            try {
                return executeProcess(command);
            } catch (InterruptedException | IOException ex) {
                throw new RuntimeException(ex);
            }
        });
        completableFuture.get();
        // remove
        LocalTime endTime = LocalTime.now();
        System.out.println("Clip Name: " + clipName);
        System.out.println("FFMPEG Process Execution Finished");
        System.out.println("Duration: " + Duration.between(startTime, endTime).toMillis() / 1000);
        return clipName;
    }
    /**
     * Create and Execute Process for each command
     */
    static Process executeProcess(String command) throws InterruptedException, IOException {
        Process clipProcess = Runtime.getRuntime().exec(command);
        clipProcess.waitFor();
        return clipProcess;
    }
}
The Entire Solution is available at Github. I am actually using CompletableFuture and running FFMPEG commands by creating Java Processes. The time it takes is too much. For a 40 minutes video, it takes more than 49 minutes, on a 64 CPU machine. I am trying to reduce the core size to 8 or something, as well improve its performance, as this kind of performance won't be acceptable for any kind of application.
22-jan-2017 update
One Update, I have changed the FFMPEG command to create clips and updated to FFMPEG 3, but there is no improvement.
ffmpeg -y -i INPUT_FILE_PATH -ss TIME_STAMP -t DURATION_TO_CLIP OUTPUT_FILE_PATH