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• avformat/demux : add duration_probesize AVOption

  29 mars 2024, par Nicolas Gaullier

  avformat/demux : add duration_probesize AVOption
  Yet another probesize used to get the durations when
  
  estimate_timings_from_pts is required. It is aimed at users interested
  
  in better durations probing for itself, or because using
  
  avformat_find_stream_info indirectly and requiring exact values : for
  
  concatdec for example, especially if streamcopying above it.
  
  The current code is a performance trade-off that can fail to get video
  
  stream durations in a scenario with high bitrates and buffering for
  
  files ending cleanly (as opposed to live captures) : the physical gap
  
  between the last video packet and the last audio packet is very high in
  
  such a case.
  Default behaviour is unchanged : 250k up to 250k << 6 (step by step).
  
  Setting this new option has two effects :
  
   override the maximum probesize (currently 250k << 6)
  
   reduce the number of steps to 1 instead of 6, this is to avoid
  
  detecting the audio "too early" and failing to reach a video packet.
  
  Even if a single audio stream duration is found but not the other
  
  audio/video stream durations, there will be a retry, so at the end the
  
  full user-overriden probesize will be used as expected by the user.
  Signed-off-by : Nicolas Gaullier <nicolas.gaullier@cji.paris>
  

  • [DH] doc/APIchanges
  • [DH] doc/formats.texi
  • [DH] libavformat/avformat.h
  • [DH] libavformat/demux.c
  • [DH] libavformat/options_table.h
  • [DH] libavformat/version.h

• Android Merging two or more videos from the List to a single synchronised video

  18 août 2017, par Alok Kumar Verma

  I’ve an activity which has the certain videos inside my recyclerview. I’ve one button which takes you to the next activity which has the VideoView.
  Now the main task is to merge the videos to single synchronous video and that video file will be played in the video View.

  The mapping is like -> EditVideoActivity.java (List of Videos in recyclerview) -> Processing the video merging into one -> saving somewhere -> the merged video getting played.

  I’ve researched on several sites about this and came to know that two things are available for this, these are :

  1. FFMPEG

  2. MP4Parser

  Now I’ve followed some questions on StackOverflow about this :

  1. FFMPEG Usage getting problem in Orientation : This doesn’t serve my motive. As this guy has used some coding.
  2. Mp4Parser : They have moved their site to Github but I got 504 gateway timeout so no guidance for that.

  Developer Android has MediaCodec and I went there it was quiet complex

  I’m sending out the data in string format or i must say the video path in array format to other activity and is working fine.

  I’ve done some homework what I did is just in media player I appended the videos. But I have to merge the videos and then it has to be played inside the videoplayer.

  1. When the button is clicked it merges the videos and saves it in a storage specified

  The same videos is now played in videoplayer

  EditVideo.java from where the data is passed from the press of the button

  audioButton.setOnClickListener(new View.OnClickListener() {
  
                    @Override
  
                    public void onClick(View view) {
  
                        //the position of the video
  
                        videoPosition = selectedVideo;
  
  
  
                        if(videoPosition != null){
  
                            Intent intent = new Intent(EditVideoActivity.this, AudioActivity.class);
  
                            intent.putExtra("videoData",videoPosition);
  
                            Log.e("VIDEO_SENT_DATA=======", videoPosition);
  
                            startActivity(intent);
  
                        }else
  
                            Toast.makeText(EditVideoActivity.this,"You have not selected any video",Toast.LENGTH_LONG)
  
                                    .show();
  
                    }
  
                });

  from here the data is getting passed, I’m working on how to merge the videos with the press of the above button

  And PreviewActivity.java is the page where the videoView is there to be played (the merged files)

  I’ve done this : Appending the videos in onCreate()

  //getting the passed value from the previous activity
  
      Bundle extras = getIntent().getExtras();
  
      final ArrayList<string> videoReceived = extras.getStringArrayList("videos");
  
      Log.e("VIDEO_RECEIVED",videoReceived.toString());
  
  
  
      mVideoPlayer.setVideoPath(String.valueOf(videoReceived.get(0)));
  
      mMediaController = new MediaController(this);
  
      mMediaController.setMediaPlayer(mVideoPlayer);
  
      mVideoPlayer.setMediaController(mMediaController);
  
      mVideoPlayer.setBackgroundColor(Color.TRANSPARENT);
  
      mVideoPlayer.requestFocus();
  
      mVideoPlayer.start();
  
      Log.e("VIDEO_SIZE===",String.valueOf(videoReceived.size()));
  
      mVideoPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
  
          @Override
  
          public void onCompletion(MediaPlayer mediaPlayer) {
  
  
  
              if( currentIndex &lt; videoReceived.size()){
  
                  String uri = String.valueOf(videoReceived.get(currentIndex));
  
                  mVideoPlayer.setVideoPath(uri);
  
                  mVideoPlayer.start();
  
                  currentIndex++;
  
              }
  
          }
  
      });
  
  </string>

• Setting individual pixels of an RGB frame for ffmpeg encoding

  15 mai 2013, par Camille Goudeseune

  I'm trying to change the test pattern of an ffmpeg streamer, Trouble syncing libavformat/ffmpeg with x264 and RTP , into familiar RGB format. My broader goal is to compute frames of a streamed video on the fly.

  So I replaced its AV_PIX_FMT_MONOWHITE with AV_PIX_FMT_RGB24, which is "packed RGB 8:8:8, 24bpp, RGBRGB..." according to http://libav.org/doxygen/master/pixfmt_8h.html .

  To stuff its pixel array called data, I've tried many variations on

  for (int y=0; y/  const double j = y/double(HEIGHT);
  
      rgb[0] = 255*i;
  
      rgb[1] = 0;
  
      rgb[2] = 255*(1-i);
  
    }
  
  }

  At HEIGHTxWIDTH= 80x60, this version yields
  , when I expect a single blue-to-red horizontal gradient.

  640x480 yields the same 4-column pattern, but with far more horizontal stripes.

  640x640, 160x160, etc, yield three columns, cyan-ish / magenta-ish / yellow-ish, with the same kind of horizontal stripiness.

  Vertical gradients behave even more weirdly.

  Appearance was unaffected by an AV_PIX_FMT_RGBA attempt (4 not 3 bytes per pixel, alpha=255). Also unaffected by a port from C to C++.

  The argument srcStrides passed to sws_scale() is a length-1 array, containing the single int HEIGHT.

  Access each Pixel of AVFrame asks the same question in less detail, so far unanswered.

  The streamer emits one warning, which I doubt affects appearance :

  [rtp @ 0x269c0a0] Encoder did not produce proper pts, making some up.

  So. How do you set the RGB value of a pixel in a frame to be sent to sws_scale() (and then to x264_encoder_encode() and av_interleaved_write_frame()) ?