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• Node.js, stream pipe output data to client with socket io-stream

  22 mai 2018, par Empha

  Sorry for a repeating topic, but i’ve searched and experimented for 2 days now and i haven’t been able to solve the problem.

  I am trying to live stream pictures every 1 second to a client via socket.io-stream using the following code :

  var args = [
  
      "-i",
  
      "/dev/video0",
  
      "-s",
  
      "1280x720",
  
      "-qscale",
  
      1,
  
      "-vf",
  
      "fps=1",
  
      config.imagePath,
  
      "-s",
  
      config.imageStream.resolution[0],
  
      "-f",
  
      "image2pipe",
  
      "-qscale",
  
      1,
  
      "-vf",
  
      "fps=1",
  
      "pipe:1"
  
  ];
  
  camera = spawn("avconv", args);    // avconv = ffmpeg

  The settings are good, and the process writes to stdout successfully. I capture all outgoing image data using this simplified code :

  var ss = require("socket.io-stream");
  
  camera.stdout.on("data", function(data) {
  
      var stream = ss.createStream();
  
      ss(socket).emit("img", stream, "newImg");
  
      // how do i write the data-object to the stream?
  
      // fs.createReadStream(imagePath).pipe(stream);
  
  });

  "socket" comes from the client using the socket.io-package, no problem there. So what i am doing is that i listen to the stdout-pipe for the "data" event. That data gets passed to the function above. That means that at this stage "data" is not a stream, its a "<buffer></buffer>code>"-object, and therefore i cannot stream it like i could previously using the commented createReadStream-statement where i read the image from disk. <strong>How do i stream the data (Buffer at this stage) to the client? Can i do this differently, perhaps not using socket.io-stream?</strong> "data" is just one part of the whole image, so perhaps two or three "data"-objects need to be put together to form the complete image.

  I tried using "stream.write(data, "binary") ;" which did transfer the Buffer-objects, problem is that there is not end of stream-event and therefore i do not know when an image is complete. I tried registering to stdout.on "close", "end", "finish", nothing triggers. Am i missing something ? Am i making it overly complex ? The reasoning behind my implementation is that i need a new stream for each complete image, is that right ?

  Thanks alot !

• I can't get bitmap from Process StandardOutput pipe ffmpeg

  7 juin 2018, par Srdjan M.

  Following article Read and Write Video Frames Using FFMPEG, I am trying to extract and process all frames from a video. The problem is that I don’t get exact same bytes in buffer and sample image.

  string Arguments = string.Format(@"-i {0} -f image2pipe -pix_fmt bgr24 -vcodec rawvideo pipe:", "output.mp4");
  
  using (Process process = new Process())
  
  {
  
      process.StartInfo.CreateNoWindow = false;
  
      process.StartInfo.UseShellExecute = false;
  
      process.StartInfo.RedirectStandardOutput = true;
  
      process.StartInfo.FileName = "ffmpeg.exe";
  
      process.StartInfo.Arguments = Arguments;
  
  
  
      process.Start();
  
  
  
      char[] buffer = new char[854 * 480 * 3];
  
  
  
      using (StreamReader reader = process.StandardOutput)
  
      {
  
          while (!reader.EndOfStream)
  
          {
  
              reader.Read(buffer, 0, buffer.Length);
  
          }
  
      }
  
  
  
      process.WaitForExit();
  
  }

• How to overlay images sequence from pipe over a video stream with ffmpeg ?

  7 juin 2018, par Dotan Simha

  I’m trying to figure out an issue with ffmpeg.
  I have the following installation :
   DeckLink Mini Recorder Card (for HDMI input)
   DeckLink Mini Monitor Card (for HDMI output)

  I’ve successfully managed to take the HDMI input from the Decklink card and output is as-is to the output card with the following command :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I tried to add a complex-filter to add an overlay of an image, with the following command, and it works :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i ./tools/bin/windows/2.png -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I’m getting a realtime feed from the decklink recorder, the image is added to the stream, and it outputs it to the output HDMI card. Everything seems to work.

  Now I tried to change the static image path to use stdin (pipe:0), and I have a tool that constantly streaming PNG images to stdout :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i pipe:0 -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  The result that i’m getting on the output HDMI card is a static image, of the first frame.
  The output of ffmpeg also changes now, and it looks like it stuck of the first-second of the stream :

  ```
  frame= 30 fps=7.4 q=-0.0 size=N/A time=00:00:01.00 bitrate=N/A speed=0.247x

  frames : 30,
  currentFps : 7,
  currentKbps : NaN,
  targetSize : NaN,
  timemark : ’00:00:01.00’
  ```

  It just remains on 00:00:01.00 and never changes.

  I tried to find the issue, and did the following :

  • Tried to stream Decklink Recorder -> static png file overlay -> Decklink Monitor = IS WORKS

  • Tried to stream static png file -> Decklink Monitor = IS WORKS

  • Tried to stream pipe:0 (PNG files) -> Decklink Monitor = IS WORKS

  • Tried to stream Decklink Recorder -> pipe:0 (PNG files overlay) -> RAW AVI file IS WORKS

  The only issue is with :
   Tried to stream Decklink Recorder -> pipe:0 (PNG files) overlay -> Decklink Monitor DOES NOT WORK

  I suspect that Decklink output is more strict, and my pipe:0 with the PNG images is not stable, and the combination of both causes it to freeze.

  Any idea how to solve it ? :(

  Thanks !