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• fate : gapless : fix mp3 tests

  20 avril 2015, par wm4

  fate : gapless : fix mp3 tests
  Seeking to a negative time did not have the desired effect of seeking to
  
  the next valid position (the file start). On the other hand, just
  
  "-ss 0" will normally seek to a position higher than 0, because it adds
  
  the start time of the file. (The start time is not 0 because the gapless
  
  code skips a few samples from the start.)
  Fix this by using the "-seek_timestamp 1" option, which makes "-ss 0" do
  
  what you’d expect it would do.
  Also put the -ss option at the right place, before -i. This actually
  
  makes it seek, instead of something completely else. The ".out-3" test
  
  is no different in the -usetoc 0/1 cases, because the seeking is
  
  inaccurate (in both cases).
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] tests/fate-run.sh
  • [DH] tests/ref/fate/gapless-mp3
  • [DH] tests/ref/fate/gapless-mp3-notoc

• Java FFMPEG - Process Builder formatting

  26 avril 2019, par Luke Price

  I need to execute an ffmpeg command using the Java Process Builder, ive found this which helped with some parts of the formatting but now need to be able to break down this :

  ffmpeg -i in.mp4 -af astats=metadata=1:reset=1,ametadata=print:key=lavfi.astats.Overall.RMS_level:file=log.txt -f null -

  I am expecting it will be in the form of this :

   "-i", inputFile, "-ss", String.valueOf(peakVolPoint(logLocation)), "-vframes", "1", outputFile

  and might look similar to this :

  "-i", inputFile ,"-af", "astats=metadata=1:reset=1,ametadata=print:key=lavfi.astats.Overall.RMS_level:file=C:\\newlog.txt" ,"-f", "null", "-"

  but need a hand.

  This is my code :

  Main :

  ffmpeg(ffmpeg_path, "-i", inputFile ,"-af", "astats=metadata=1:reset=1,ametadata=print:key=lavfi.astats.Overall.RMS_level:file=C:\\newlog.txt" ,"-f", "null", "-");

  Function :

      public static String ffmpeg(String... strings) throws IOException {
  
          List<string> params = Arrays.asList(strings);
  
  
  
          Process processDuration = new ProcessBuilder(params).redirectErrorStream(true).start();
  
          StringBuilder strBuild = new StringBuilder();
  
          try (BufferedReader processOutputReader = new BufferedReader(
  
                  new InputStreamReader(processDuration.getInputStream(), Charset.defaultCharset()));) {
  
              String line;
  
              while ((line = processOutputReader.readLine()) != null) {
  
                  strBuild.append(line + System.lineSeparator());
  
              }
  
              try {
  
                  processDuration.waitFor();
  
              } catch (Exception e) {
  
                  e.printStackTrace();
  
              }
  
          }
  
          String outputJson = strBuild.toString().trim();
  
          System.out.println(outputJson);
  
          return outputJson;
  
  </string>

  Thanks !

• Feeding content of an X-Window to a virtual camera

  11 mai 2022, par Ingo

  I want to feed a virtual webcam device from an application window (under Linux/Xorg). I have so far just maximised the window and then used ffmpeg to grab the whole screen like this :

  


  ffmpeg \
    -f x11grab -framerate 15 -video_size 1280x1024 -i :0+0,0 \
    -f v4l2 -vcodec rawvideo -pix_fmt yuv420p /dev/video6


  


  where /dev/video6 is my v4l2loopback device. This works and I can use the virtual camera in video calls in chrome. This also indicates that the v4l2loopback module is correctly loaded into the kernel.

  


  Unfortunately, it seems that ffmpeg can only read the whole screen, but not an application window. gstreamer on the other hand can. Playing around with gst-launch-1.0, I was hoping that I could get away with something like this :

  


  gst-launch-1.0 ximagesrc xid=XID_OF_MY_WINDOW \
    ! "video/x-raw" \
    ! v4l2sink device=/dev/video6


  


  However, that complains that Device '/dev/video6' is not an output device.

  


  Given that ffmpeg seems happy to write to /dev/video6 I also tried piping the gst output to ffmpeg like this :

  


  gst-launch-1.0 ximagesrc xid=XID_OF_MY_WINDOW \
    ! "video/x-raw" \
    ! filesink location=/dev/stdout \
    | ffmpeg -i - -codec copy -f v4l2 -vcodec rawvideo -pix_fmt yuv420p /dev/video6


  


  But then ffmpeg complains about Invalid data found when processing input.

  


  This is running inside an xvfb headless environment, so mouse interactions will not work. This rules out obs as far as I can see.

  


  I'm adding the chrome tag, because I see that chrome in principle would also provide a virtual camera via the --use-fake-device-for-media-stream switch. However, it seems that this switch only supports a static file rather than a stream.

  


  Although I don't see why, it might be relevant that the other "application window" window is simply a second browser window. So the setup is google meet (or similar) in one browser window and the virtual camera gets fed vrom a second browser window.