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• Android and ffmpeg, x264 bitrate and videosize

  11 décembre 2012, par brux

  I am concatenating two mp4 files by first converting them to mpeg, once I have concatenated the mpegs I want to produce a final larger mp4.

  The following code works fine in order to produce the mpegs

  ffmpeg -i one.mp4 -q:v 2 -vcodec mpeg2video -acodec copy one.mpg
  
  
  
  
  
  
  
  ffmpeg -i two.mp4 -q:v 2 -vcodec mpeg2video -acodec copy two.mpg

  After concatenating these 2 files (using java) I produce the final mp4 like this :

  ffmpeg -i joined.mpg -vcodec libx264 -acodec copy joined.mp4

  The command works and a low quality mp4 is produced since I am not specifying a 'bitrate' or 'videosize' in the MediaRecorder class object.

  Here are the settings I use on my MediaRecorder object when encoding the video in Android

          mediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
  
          mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
  
          mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
  
          mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
  
          mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);

  if I add the following two lines in order to increase the bitrate and videosize of one.mp4 and two.mp4 then the resultant mp4's playback fine using the default player on android, but after converting to mpg and then concatenating and then using the above ffmpeg command to encode a new mp4, th resultant joined.mp4 is less quality than the original mp4's are started out with (one.mp4 and two.mp4)

          mediaRecorder.setVideoEncodingBitRate(2000000);
  
          mediaRecorder.setVideoSize(800, 480);

  Do i need to add more parameters to my ffmpeg commands in order to do this successfully ?

• FFMPEG (WINDOWS) - Jerky Videos with vidstabdetect & vidstabtransform

  26 avril 2016, par Onish Mistry

  I require to stabilize multiple video clips and finally stitch all the clips, along with images into one final video. These "Scenes" consisting video clips as well as images also can have overlays like Texts and/or other Images.

  Basically the code I have in place as of now does everything for me just fine, where all the video clips are first converted into frame images. It then reads all the frames, puts on the overlays, adds a fade transition in-between "Scenes".

  Coming to the issue I am facing with stabilization, when I extract image frames out of the stabilized video clip and simply try to recreate video from those extracted image frames, it comes out with a weird jerk, almost like as if it is missing those stabilization calculations or something, not sure. It still looks a bit stabilized but with missing frames. I have checked duration and number of frames extracted, everything matches with the source, non-stabilized video.

  Below is the command used to stabilize the video, result of which is a perfectly stabilized video.

  ffmpeg -i 1.MOV -r 30 -vf vidstabdetect=result="transforms.trf" -f null NUL && ffmpeg -i 1.MOV -r 30 -vf vidstabtransform=smoothing=30:input="transforms.trf" -vcodec libx264 -b:v 2000k -f mp4 results.mp4

  Below is the command I use for video to image :

  ffmpeg -i results.mp4 -r 30 -qscale 1 -f image2 %d.jpg

  Below is the command I use for image to video :

  ffmpeg -i %d.jpg -r 30 -vcodec libx264 -b:v 2000k -f mp4 final.mp4

  Any help or suggestions are welcomed and appreciated.

  Thanks,

• Frames grabbed from UDP H264 stream with ffmpeg are gray/distorded

  12 septembre 2019, par Clément Bourdarie

  I am grabbing frames from a udp h264 stream with Javacv’s FFMPEG on windows, and putting them into a JavaFX imageview. The problem is that most of the image isn’t received well (it is gray, distored...) :

  

  I used to have the same problem before and I made it work by using flush on the frame grabber after each frame, but I forgot to save my work and lost it, and this time the correction doesn’t work.

  Here’s the part where i configure/launch FFMPEG :

          final Java2DFrameConverter converter = new Java2DFrameConverter();
  
  
  
          // Show drone camera
  
          FFmpegFrameGrabber grabber = new FFmpegFrameGrabber("udp://227.0.0.1:2200");
  
  
  
          grabber.setFrameRate(_frameRate);
  
          grabber.setFormat(_format);
  
          grabber.setVideoBitrate(25000000);
  
          grabber.setVideoOption("preset", "ultrafast");
  
          grabber.setNumBuffers(0);
  
  
  
          grabber.start();
  
  
  
          // Grab frames as long as the thread is running
  
          while(_running){
  
                 final Frame frame = grabber.grab();
  
                 if (frame != null) {
  
                     final BufferedImage bufferedImage = converter.convert(frame);
  
                     if (bufferedImage != null) {
  
                           _cameraView.setImage(SwingFXUtils.toFXImage(bufferedImage, null));
  
                     }
  
                  }
  
                  Thread.sleep( 1000 / _frameRate );// don't grab frames faster than they are provided
  
                  grabber.flush();
  
          }
  
          _grabber.close();

  _format is "h264" and _frameRate is 30.

  Also, the system is flooded with prints like these (I’m not sure they are related to the problem though) :

  [h264 @ 00000000869c0a80] Invalid NAL unit 4, skipping.
  
  [h264 @ 00000000869c0a80] Invalid NAL unit 4, skipping.
  
  [h264 @ 00000000869c0a80] Invalid NAL unit 4, skipping.
  
  [h264 @ 00000000869c0a80] Reference 6 >= 4
  
  [h264 @ 00000000869c0a80] error while decoding MB 115 14, bytestream 1979
  
  [h264 @ 00000000869c0a80] concealing 6414 DC, 6414 AC, 6414 MV errors in P frame
  
  [h264 @ 0000000078f81180] Invalid NAL unit 0, skipping.
  
  [h264 @ 0000000078f81180] Invalid NAL unit 0, skipping.
  
  [h264 @ 0000000078f81180] concealing 4811 DC, 4811 AC, 4811 MV errors in B frame

  I don’t understand why it doesn’t work anymore