Recherche avancée

Sur d’autres sites (9832)

• FFMPEG in android issue

  9 janvier 2012, par Antu

  I have successfully compiled the FFMPEG library to android using NDK.
  (using Rock Player FFMPEG implementation)http://www.rockplayer.com/download/rockplayer_ffmpeg_git_20100418.zip

  I know that FFMPEG supports .avi, divX, mov ect. But I created a mediaplayer and tried to run them but I was not able to play them. I is this the right way to use the FFMPEG library. Can Any one Help.I am able to play defaut video, mp4, 3gp etc. Here is the code for mediaplayer

     public native String  stringFromJNI();
  
        static {
  
           System.loadLibrary("ffmpeg");
  
           System.loadLibrary("ffmpeg-test-jni");
  
               }
  
      @Override
  
        public void onCreate(Bundle savedInstanceState) {
  
        super.onCreate(savedInstanceState);
  
  
  
  
  
      setContentView(R.layout.main);
  
  
  
      TextView  tv =(TextView) findViewById(R.id.textView1);
  
      tv.setText( stringFromJNI() );
  
  
  
  
  
      System.gc();
  
  
  
      Log.d("Video FFmpeg ", "**");
  
  
  
      getWindow().setFormat(PixelFormat.TRANSLUCENT);
  
      String filepath = Environment.getExternalStorageDirectory()+"/simple.avi";
  
  
  
      Log.d("File path", filepath);
  
  
  
      MediaController mc = new MediaController(this); 
  
  
  
      VideoView video=(VideoView) findViewById(R.id.video);
  
      mc.setMediaPlayer(video);
  
      video.setVideoPath(filepath);
  
      video.setMediaController(mc);
  
      mc.show();
  
      //video.setVideoPath("/mnt/sdcard/Movies/Ishq-Hothon-Se.3gp");
  
  
  
      video.start();     
  
      View nextButton = findViewById(R.id.button1);
  
      nextButton.setOnClickListener(this);
  
      }
  
  
  
  
  
  
  
    @Override
  
    public void onClick(View v) {
  
    // TODO Auto-generated method stub
  
    Intent i=new Intent(this,NextVideo.class);
  
     startActivity(i);
  
  
  
    }
  
  
  
    }

• Stream video from ffmpeg and capture with OpenCV

  10 décembre 2014, par chembrad

  I have a video stream coming in on rtp to ffmpeg and I want to pipe this to my OpenCV tools for live streaming processing. The rtp linkage is working because I am able to send the incoming data to a file and play it (or play if via ffplay). My OpenCV implementation is functional as well because I am able to capture video from a file and also a webcam.

  The problem is the streaming to OpenCV. I have heard that this may be done using a named pipe. First I could stream the ffmpeg output to the pipe and then have OpenCV open this pipe and begin processing.

  What I’ve tried :

  I make a named-pipe in my cygwin bash by :

      $ mkfifo stream_pipe

  Next I use my ffmpeg command to pull the stream from rtp and send it to the pipe :

      $ ffmpeg -f avi -i rtp://xxx.xxx.xxx.xxx:1234 -f avi -y out.avi > stream_pipe

  I am not sure if this is the right way to go about sending the stream to the named pipe but it seems to be accepting the command and work because of the output from ffmpeg gives me bitrates, fps, and such.

  Next I use the named pipe in my OpenCV capture function :

      $ ./cvcap.exe stream_pipe

  where the code for cvcap.cpp boils down to this :

      cv::VideoCapture *pIns = new cv::VideoCapture(argv[1]);

  The program seems to hang when reaching this one line, so, I am wondering if this is the right way of going about this. I have never used named pipes before and I am not sure if this is the correct usage. In addition, I don’t know if I need to handle the named pipe differently in OpenCV—change code around to accept this kind of input. Like I said, my code already accepts files and camera inputs, I am just hung up on a stream coming in. I have only heard that named pipes can be used for OpenCV—I haven’t seen any actual code or commands !

  Any help or insights are appreciated !

  UPDATE :

  I believe named pipes may not be working in the way I intended. As seen on this cygwin forum post :

  The problem is that Cygwin’s implementation of fifos is very buggy. I wouldn’t recommend using fifos for anything but the simplest of applications.

  I may need to find another way to do this. I have tried to pipe the ffmpeg output into a normal file and then have OpenCV read it at the same time. This works to some extent, but I imagine in can be dangerous to read and write from a file concurrently—who knows what would happen !

• FFmpeg on iPhone - Modifying Video Orientation

  6 avril 2015, par Matthew McGoogan

  I’m messing with h264 videos loaded with FFmpeg on the iPhone 3GS. The problem is any videos recorded in "Portrait" orientation have a transformation matrix applied to them causing them to display rotated 90 degrees counter-clock.

  From what I understand thus far, I just need to modify the transform matrix in the ’tkhd’ atom. The problem is I am having trouble accessing or modifying this data. I checked out the FFmpeg implementation for :

  static int mov_read_tkhd(MOVContext *c, ByteIOContext *pb, MOVAtom atom)

  which clearly shows how the matrix is accessed in avformat but when I try to access the header bytes using the same functions I am not getting any rational values. Even if I were to successfully pull the matrix I’m not sure how to replace it ? FFmpeg has functions for retrieving and appending to the track header but nothing for replace it seems ?

  Any help would be greatly appreciated.

  Thanks,
  Matt.