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• Why are there multiple .m3u8 requests made by the browser ?

  20 mai 2020, par 47fa0c

  I usually download my lectures instead of watching them on the online player provided by my university. I do this by finding requests that include .m3u8 in their url. There always seems to be two of these for each of the videos that I want to download, with one slight difference in the urls but otherwise identical. Why is that the case ?

  



  My wild guess is that one of them is supposed act as a backup if the other failed to fetch but I am not sure.

  



  I can't share the urls as they contain copyrighted material but it looks something like

  



  domain/a/b/hashedvalue1/c/video.mp4/index.m3u8


  



  and

  



  domain/a/b/hashedvalue2/c/video.mp4/index.m3u8


  



  Thanks for your help :)

  


• Record live stream using ffmpeg as Process in Java

  26 décembre 2020, par Serbroda

  I can not figure out how to start a Process in Java for recording a live stream with ffmpeg.

  



  I've tried several solutions, but my current code looks like this (simplified) :

  



  public void startDownload() {
    String[] processArgs = new String[] {
            "ffmpeg", 
            "-i", 
            "https://bitdash-a.akamaihd.net/content/sintel/hls/playlist.m3u8", 
            "-c", 
            "copy", 
            "-bsf:a", 
            "aac_adtstoasc", 
            "C:\\temp\\test.mp4"
    };
    ProcessBuilder processBuilder = new ProcessBuilder(processArgs);
    try {
        process = processBuilder.start();
        process.wairFor(); // Do I need this? Actually the stream is running forever until I stop it manually.
        BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()));
        String line = null;
        while ((line = br.readLine()) != null) { // this blocks forever
            System.out.println(line);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}


  



  The problem is, that something blocks the process from starting. In this example the br.readLine() blocks it forever and I can not get any output from the process.

  



  But after killing the jar / stopping launch config in Intellij, the process begins to work and I have to kill it via task manager.

  



  Running a process that is not recording a live stream like just executing ffmpeg works by the way.

  



  I'm using Windows, JDK 14, IntelliJ.

  


• How to record lifestream in fluent-ffmpeg with screenshots on fixed intervals ?

  3 juin 2020, par philippos

  I am using typescript to record a lifestream using my built-in webcam on my MAC. My goal is to record a video of 1 min length, and taking a screenshot every 10 seconds.

  



  Here is my code :

  



  import * as ffmpeg from 'fluent-ffmpeg'
ffmpeg()
    .input('0')
    .inputFormat('avfoundation')
    .inputFPS(30)
    .outputOptions([`-vf fps=1/10`])
    .output(`thumb%02d.jpg`)
    .duration(60)
    .save('test.mpg')


  



  I am succeeding to take 6 screenshots in a minute, however, the video keeps recording even after it's more than one minute, until I stop recording manually by ^ + C from terminal.

  



  I have to note that if I comment out the screenshot lines as following :

  



  import * as ffmpeg from 'fluent-ffmpeg'

ffmpeg()
    .input('0')
    .inputFormat('avfoundation')
    .inputFPS(30)
    // .outputOptions([`-vf fps=1/10`])
    // .output(`thumb%02d.jpg`)
    .duration(60)
    .save('test.mpg')


  



  Then it will stop recording automatically after 1 minute.

  



  So how to make it record a 1 min video, take screenshots at intervals, and then stop automatically ?

  



  UPDATE

  



  I just read on the documentation the following :

  



  


  Also note that when calling output(), you should not use the save() or stream() (formerly saveToFile() and writeToStream()) methods, as they already add an output. Use the run() method to start processing.

  


  



  So as I understood, we can do both recording a video AND taking screenshots on the same time.

  



  The following code takes screenshots every 10 seconds for a minute, without recording a video.

  



  import * as ffmpeg from 'fluent-ffmpeg'
ffmpeg()
  .input('0')
  .inputFormat('avfoundation')
  .inputFPS(30)
  .duration(60)
  .outputOptions([`-vf fps=1/10`])
  .output(`thumb%02d.jpg`)
  })
  .run()


  



  However, I still want to know if there is any workaround to do both recording and taking screenshots at the same time.