Question

I am running ffmpeg.exe through a Java code to encode a video file. How will my program come to know when ffmpeg terminated (i.e. video file is encoded)?

Here is the code:

Runtime.getRuntime().exec("ffmpeg -ac 2 -i audio.wav -i video.flv -sameq out.flv");

Answer 1

You can use waitFor() method of java.lang.Process:

Process p = Runtime.getRuntime().exec("ffmpeg...");
int exitValue = p.waitFor()

With this, the current thread waits until the Process p has terminated.

EDIT:

You can try to see the output from ffmpeg:

class StreamDump implements Runnable {

    private InputStream stream;

    StreamDump(InputStream input) {
        this.stream = input;
    }

    public void run() {
        try {
            int c;
            while ((c = stream.read()) != -1) {
                System.out.write(c);
            }
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }
}

and

Process p = Runtime.getRuntime().exec("ffmpeg.exe...");
new Thread(new StreamDump(p.getErrorStream()), "error stream").start();
new Thread(new StreamDump(p.getInputStream()), "output stream").start();
try {
    p.waitFor();
} catch (InterruptedException e) {
    e.printStackTrace();
}
System.out.println("Exit value: " + p.exitValue());