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• how to deal with live raw h264 stream to send over network

  3 novembre 2015, par jinhwan

  what I want to do is that send live camera stream which is encoded by h264 to gstreamer. I already have seen many example which send over network by using rtp and mpeg-ts. But problem is that all those examples assume that the input will be served by fixed file or live stream which is already transcoded in transport portocol like below.

  client :
  gst-launch-1.0 videotestsrc horizontal-speed=5 ! x264enc tune="zerolatency" threads=1 ! mpegtsmux ! tcpserversink host=192.168.0.211 port=8554

  server : gst-launch-1.0 tcpclientsrc port=8554 host=192.168.0.211 ! tsdemux ! h264parse ! avdec_h264 ! xvimagesink

  But, My camera offer the below interface (written in java, actually work on adnroid). The interface offer just live raw h264 blocks.

  mReceivedVideoDataCallBack=newDJIReceivedVideoDataCallBack(){
  
      @Override
  
      public void onResult(byte[] videoBuffer, int size)
  
      {
  
  }

  I can create tcp session to send those data block. But, how can i make those data which is not packed in transport protocol into format which is understable by gstreamer tcpclient ?
  Transcode the original stream in ts format in the camera side can be a solution. But i have no clue to do transcode from non-file and non-transport-format data. I have searched gstreamer and ffmpeg, But I could not derive a way to deal h264 block stream using the supported interface, unitl now.
  Or, Are there any way to make gstreamer to directly accept those simple raw h264 block ?

• Saving Standard Output in memory instead of a file in C#

  19 décembre 2016, par Shawn W

  There is no online tutorial or even a book, for handling Standard Output with C#.

  I want to save standard output in a variable (memory) instead of a file in Shell Execution.

  This for storing thumbnail image from a video file with ffmpeg.

  The below is my code.

  public static void GetThumbnail(string video, string thumbnail, string ffdir)
  
  {
  
      var cmd = " -ss 00:01:00.000 -i " + '"' + video + '"' + " -vcodec rawvideo -vframes 1 -an -f rawvideo -s 320x240 pipe:1 ";
  
  
  
  
  
      var startInfo = new ProcessStartInfo
  
      {
  
          WindowStyle = ProcessWindowStyle.Normal,
  
          FileName = ffdir + "\\ffmpeg.exe ",
  
          Arguments = cmd,
  
          RedirectStandardOutput = true,
  
          UseShellExecute = false
  
      };
  
  
  
      var process = new Process
  
      {
  
          StartInfo = startInfo
  
      };
  
  
  
      process.OutputDataReceived += ProcessOnOutputDataReceived;
  
      process.ErrorDataReceived += ProcessOnOutputDataReceived;
  
  
  
      process.Start();
  
  
  
      process.WaitForExit(1000);
  
  }
  
  
  
  private static void ProcessOnOutputDataReceived(object sender, DataReceivedEventArgs dataReceivedEventArgs)
  
  {
  
      ....
  
  }

  But it does not enter to the event handler function (ProcessOnOutputDataReceived) when GetThumbnail function launched.

  Is there any clue to solve this problem ?

  I referred the question and answer here :
  getting mulitple images from a single stream piped from ffmpeg stdout

  But it does not help. It seems that the code for previous .NET versions.

• Why can I not change the number of frames (nframes) in a gganimate animation ? SOLVED

  26 décembre 2022, par Gekin

  I have produced an animation per gganimate and rendered it per ffmpeg. It works just fine, but only, if I do not change the number of frames. If I do set the number of frames, I get this error message :

  


  nframes and fps adjusted to match transition
Error parsing framerate 8,4.                           
Error: Rendering with ffmpeg failed


  


  I produced the gganim MonthlyAveragePrecipitationMap the following way :

  


  options(scipen = 999, OutDec  =  ",")

MonthlyAveragePrecipitationMap = ggplot(MonthlyAverageExtremePrecipitation) + 
  geom_path(data = map_data("world","Germany"),
            aes(x = long, y = lat, group = group)) +
  coord_fixed(xlim = c(6,15),
              ylim = c(47,55)) + 
  geom_point(aes(x=lon, y=lat, 
                 colour = ShareOfExtremePrecipitationEvents,
                 group = MonthOfYear),
             size = 3) + 
  scale_color_gradient(low="blue", high="yellow") + 
  xlab("Longitude (degree)") +
  ylab("Latitude (degree)") + 
  theme_bw() +
  transition_manual(frames = MonthOfYear) + 
  labs(title = '{unique(MonthlyAverageExtremePrecipitation$MonthOfYear)[as.integer(frame)]}', 
       color = paste0("Share of Extreme Precipitation Events \namong all Precipitation Events")) 


  


  I call the animation the following way :

  


  animate(MonthlyAveragePrecipitationMap,
        nframes = 300,
        renderer =
          ffmpeg_renderer(
            format = "auto",
            ffmpeg = NULL,
            options = list(pix_fmt = "yuv420p")))



  


  I used this exact code just a few days ago and it worked fine.

  


  Has someone had similar experiences ?
Thanks in advance.

  


  EDIT : Problem solved.

  


  

  • Problem : Changing the decimal seperator from . to , per options(dec=",")

  


  • Solution : Changing the decimal seperator locally within the axis scaling per function.