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• Gstreamer errors when streaming on windows

  19 juillet 2014, par user2656632

  I tried to streaming video by gstreamer using this :

  Sender :

  gst-launch ksvideosrc ! ffmpegcolorspace ! ffenc_mpeg2video gop-size=1 ! mpegtsmux ! rtpmp2tpay ! udpsink host=127.0.0.1 port=5000

  Receiver :

  gst-launch udpsrc port=5000 caps="application/x-rtp, media=video, clockrate=90000, encoding-name=MP2TS" ! rtpmp2tdepay ! ffdemux_mpegts ! ffdec_mpeg2video ! ffmpegcolorspace ! directdrawsink

  It works, but wrong. I got very low fps and I got this output :

  0:00:01.583091000 19496   02404840 ERROR                 ffmpeg .:0:: invalid mb
  
   type in I Frame at 33 21
  
  0:00:01.590091000 19496   02404840 ERROR                 ffmpeg .:0:: Warning MV
  
  s not available
  
  0:00:20.763188000 19496   02404840 ERROR                 ffmpeg .:0:: invalid mb
  
   type in I Frame at 33 21
  
  0:00:20.764188000 19496   02404840 ERROR                 ffmpeg .:0:: Warning MV
  
  s not available
  
  0:00:20.816191000 19496   02404840 ERROR                 ffmpeg .:0:: skipped MB
  
   in I frame at 7 22
  
  0:00:20.817191000 19496   02404840 ERROR                 ffmpeg .:0:: Warning MV
  
  s not available
  
  0:00:20.847192000 19496   02404840 ERROR                 ffmpeg .:0:: skipped MB
  
   in I frame at 24 19
  
  0:00:20.949198000 19496   02404840 ERROR                 ffmpeg .:0:: skipped MB
  
   in I frame at 3 20
  
  0:00:20.970199000 19496   02404840 ERROR                 ffmpeg .:0:: invalid mb
  
   type in I Frame at 36 19
  
  0:00:20.982200000 19496   02404840 ERROR                 ffmpeg .:0:: skipped MB
  
   in I frame at 14 20
  
  0:00:21.007202000 19496   02404840 ERROR                 ffmpeg .:0:: slice mism
  
  atch
  
  0:00:21.031203000 19496   02404840 ERROR                 ffmpeg .:0:: skipped MB
  
   in I frame at 13 20
  
  0:00:21.060205000 19496   02404840 ERROR                 ffmpeg .:0:: skipped MB
  
   in I frame at 31 24

  How I can fix these issues ?

• WebRTC Experiment : Chrome windows audio not sync

  10 juillet 2014, par putoshop

  I tried to make the audio work for Chrome using this Git Repo, but I’m having a sync problem with video and audio. The audio finished playing earlier. The video seems to be correct. I noticed that when I play the blob, the audio is playing fast.

  I was able to make the audio work by commenting the line the throws error in the condition that check if sampleRate is less than 22050 or greater than 96000 in RecordRTC.js.

  I tried to adjust the sampleRate other values and noticed that If the sampleRate is low, the audio plays slow and if the sampleRate is high, the audio plays fast. I was able to make the audio and video somewhat sync but it seems the pitch of the audio becomes noticeable lower than the expected pitch.

  I’ve also tried FFMPEG to adjust the length of the audio to match the video length, but didn’t been able to make it work.

  the extensions of the files that are uploaded to the server for Chrome are .webm(video) and .wav(audio).

• How to take a screenshot of desktop fast with Java in Windows (ffmpeg, etc.) ?

  4 mars 2015, par Setsuna

  I would like to use java to take a screenshot of my machine using FFMPEG or some other solution. I know linux works with ffmpeg without JNI, but running it in Windows does not work and may require (JNI ?) is there any sample of some simple Java class (and anything else necessary) to capture a screenshot runnable in a windows environment ? Is there some alternative to FFMPEG ? I want to take screenshot at a rate faster than the Java Robot API, which I have found to work at taking screenshots, but is slower than I would like.

  I know in Linux this works very fast :

  import com.googlecode.javacv.*;
  
  
  
  public class ScreenGrabber {
  
      public static void main(String[] args) throws Exception {
  
          int x = 0, y = 0, w = 1024, h = 768;
  
          FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(":0.0+" + x + "," + y);
  
          grabber.setFormat("x11grab");
  
          grabber.setImageWidth(w);
  
          grabber.setImageHeight(h);
  
          grabber.start();
  
  
  
          CanvasFrame frame = new CanvasFrame("Screen Capture");
  
          while (frame.isVisible()) {
  
              frame.showImage(grabber.grab());
  
          }
  
          frame.dispose();
  
          grabber.stop();
  
      }

  This does not work in windows environment. Am not sure if there is some way I could use this same code, but use javacpp to actually get it working without having to change much of the above code.

  Goal is to take screenshots of screen fast, but then stop after it takes a screenshot that is "different", aka. screen changed because of some event like, a window is window closed, etc.