How to use screenrecordex with Android app?

I tried to use screenrecordex to record screen using my app (not command prompt). I pushed this file to /data/data/tmp folder and set the specified permission (755) through code. Now when I execute process to record screen, it shows that process has started but after then my app hangs and nothing goes well. I terminated my app and saw that a video file is created on my sd card with size 0 bytes. I debugged my code and I found issue while running this file through code. Below is sample of my code to execute this and record video:

try {
final Process process = Runtime.getRuntime.exec(recordxFile + " /sdcard/demo.mp4");
// BufferedReader bufferedReader = new BufferedReader(
// new InputStreamReader(process.getInputStream()));
LogUtils.LogD("Recording...");
// String line;
// while ((line = bufferedReader.readLine()) != null) {
// LogUtils.LogD("Output", line);
// }
} catch (IOException | InterruptedException e) {
e.printStackTrace();
}

It app hangs at bufferedReader.readLine() while reading the output of process. I also tried to run --help and --verbose but got no output but in that case app does not hang.

So, can you please tell me what I am doing wrong or suggest a way to record video by executing this file from Android app.

Thanks.