How to read ffmpeg response from java and use it to create a progress bar?

Question

I am working on creating a progress bar for ffmpeg in java. So for that I need to execute a command, then read all of the progress:

String[] command = {"gnome-terminal", "-x", "/bin/sh", "-c","ffmpeg -i /home/tmp/F.webm /home/tmp/converted1.mp4"};

Process process = Runtime.getRuntime().exec(command);

This runs perfectly. However, I need to capture the all of the progress to make a progress bar. So how can I read that data from java?

Answer 1

Here's a complete example for you which should get you started

import java.io.*;
import java.util.Scanner;
import java.util.regex.Pattern;

class Test {
  public static void main(String[] args) throws IOException {
    ProcessBuilder pb = new ProcessBuilder("ffmpeg","-i","in.webm","out.mp4");
    final Process p = pb.start();

    new Thread() {
      public void run() {

        Scanner sc = new Scanner(p.getErrorStream());

        // Find duration
        Pattern durPattern = Pattern.compile("(?<=Duration: )[^,]*");
        String dur = sc.findWithinHorizon(durPattern, 0);
        if (dur == null)
          throw new RuntimeException("Could not parse duration.");
        String[] hms = dur.split(":");
        double totalSecs = Integer.parseInt(hms[0]) * 3600
                         + Integer.parseInt(hms[1]) *   60
                         + Double.parseDouble(hms[2]);
        System.out.println("Total duration: " + totalSecs + " seconds.");

        // Find time as long as possible.
        Pattern timePattern = Pattern.compile("(?<=time=)[\\d.]*");
        String match;
        while (null != (match = sc.findWithinHorizon(timePattern, 0))) {
          double progress = Double.parseDouble(match) / totalSecs;
          System.out.printf("Progress: %.2f%%%n", progress * 100);
        }
      }
    }.start();

  }
}

Output:

Total duration: 117.7 seconds.
Progress: 7.71%
Progress: 16.40%
Progress: 25.00%
Progress: 33.16%
Progress: 42.67%
Progress: 51.35%
Progress: 60.57%
Progress: 69.07%
Progress: 78.02%
Progress: 86.49%
Progress: 95.94%
Progress: 99.97%

You may also consider using some kind of Java bindings for ffmpeg such as jjmpeg which may provide what you need in a more robust way.

EDIT

With ffmpeg 2.0, time output is HH:mm:ss.S so the timePattern needs a to incorporate a :

Pattern timePattern = Pattern.compile("(?<=time=)[\\d:.]*");

In addition, the dur will need to be split on : and summed together

String[] matchSplit;
while (null != (match = sc.findWithinHorizon(timePattern, 0))) {
    matchSplit = match.split(":")
    double progress = Integer.parseInt(matchSplit[0]) * 3600 +
        Integer.parseInt(matchSplit[1]) * 60 +
        Double.parseDouble(matchSplit[2]) / totalSecs;
//...