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• FFMPEG : How to extract multichannel track from m4v, mix it down and save the stereo downmix as "left" and "right" ?

  1er juin 2017, par chillynilly

  just like the title already says : I want to extract a multichannel track (5.1) from an .m4v, mix this track down and save the output as separate files, so in the end I want to have something like ’downmix_left.wav’ and ’downmix_right.wav’
  I know how to do a downmix and I know how to split the audio, but I do not know how to do it in one step, which would save me a lot of time.

  This is the command I use for splitting :

  ffmpeg -i "video.m4v" -vn -filter_complex \
  
  "[0:2]channelsplit=channel_layout=5.1(side)[FL][FR][FC][LFE][SL][SR]" \ 
  
  -map "[FL]" video_left.wav \ 
  
  -map "[FR]" video_right.wav \ 
  
  -map "[FC]" video_center.wav \ 
  
  -map "[LFE]" video_lfe.wav \ 
  
  -map "[SL]" video_back_left.wav \ 
  
  -map "[SR]" video_back_right.wav

  And this is the command for the downmix of a multichannel track :

  ffmpeg -i "video.m4v" -vn -map 0:2 -ac 2 \ 
  
  -af "aresample=matrix_encoding=dplii" video_downmix.wav

  Is it possible to combine these and if so, how can it be done :D ? I would appreciate it very much if you could help me out here.

• How to save recorded ffmpeg webcam video to red5

  20 juillet 2014, par user3451310

  im trying to make a webcam recording program that can be accessed remotely by other users. i completed the recording locally but when i try to save it to red5 rtmp ://localhost/oflaDemo/streams/output.flv, no output produced to the streams directory and i don’t know how to stream it from other users while recording. can someone help me on this problem ?tnx heres my code :

  Thread webcam = new Thread()
  public void run()

      String fileName = new SimpleDateFormat("yyyy-MM-dd-hhmm").format(new Date());
  
     try {  
  
     OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0);  
  
     grabber.start();  
  
     opencv_core.IplImage grabbedImage = grabber.grab();  
  
     CanvasFrame canvasFrame = new CanvasFrame("Video recorder");  
  
     canvasFrame.setCanvasSize(grabbedImage.width(), grabbedImage.height());  
  
     grabber.setFrameRate(grabber.getFrameRate());  
  
  
  
  
  
  
  
     FFmpegFrameRecorder recorder = new FFmpegFrameRecorder("rtmp://localhost/oflaDemo/streams/output.flv", 800, 600);
  
  
  
     recorder.setFormat("flv");  
  
     recorder.setFrameRate(6);  
  
     recorder.setVideoBitrate(1024 * 1024); 
  
  
  
  
  
  
  
  
  
     recorder.start();
  
  
  
  
  
  
  
     while (canvasFrame.isVisible() && (grabbedImage = grabber.grab()) != null) {  
  
       canvasFrame.showImage(grabbedImage);  
  
       recorder.record(grabbedImage);  
  
     }  
  
     recorder.stop();  
  
     grabber.stop();  
  
     canvasFrame.dispose();  
  
  
  
  
  
     recorder.record();
  
  
  
   } catch (FrameGrabber.Exception ex) {  
  
     Logger.getLogger(web.class.getName()).log(Level.SEVERE, null, ex);  
  
   } catch (FrameRecorder.Exception ex) {  
  
     Logger.getLogger(web.class.getName()).log(Level.SEVERE, null, ex);  
  
   }  

   ;
  webcam.start() ;

  }        

• Android : How to save two overlapped videos as one using mediacodec ?

  27 avril 2015, par Seba Niepodam

  I want to do something similar to this on android.

  I want to load video from file and display it twice with some transformations (mostly resize). And i want to encode it as one video file.

  Is it possible to do it in native android ? With mediacodec or in any other way ?

  I know there is a ffmpeg but i have trouble compiling it and working with Xamarin.