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• Piping stdout from child process directly to google cloud storage. Node.js

  2 octobre 2018, par glenn

  anyone here with expertise on piping to google cloud storage ?

  i am using FFmpeg on a server, and want to pipe to my storage bucket.

  I can get it working when I save FFmpeg output to a file, then createReadableStream from the file, and then pipe that to createWriteStream()

  however, I dont want to generate a static file, and then go through that process every time

  Why can I not just simply pipe FFmpeg.stdout.pipe(file.createWriteStream()) ?

  FYI : I am running FFmpeg as a child process

        spawnFFMPEG = () => {
  
  this.ffmpeg = child_process.spawn('ffmpeg',
  
    [
  
      '-f', 'lavfi', '-i', 'anullsrc',
  
      '-thread_queue_size', '512',
  
      '-i', '-',
  
      '-shortest', '-vcodec', 'copy',
  
      '-f', 'avi',
  
      'pipe:1'
  
    ]
  
  )
  
  
  
   this.ffmpeg.stdout.pipe(myWritableStream)

• Nodejs spawn - child processes

  24 février 2019, par z Eyeland

  My nodejs application is running on raspberry Pi. The program uses spawn child process to trigger bash scripts which record or compress the previous recorded file. The program records fine. After recording the user selects the compress button. This kills the recording spawn process and fires the bash script for compression. The issue I am having is that whenever the video length gets around 1min long the compression spawn process times out or something. I ran ps -ef to view all process and i noticed that the compression script is still there. She the video length is short - the compression spawn process completes its cycle and send api request to shutdown the process. Here is some code

  Api with console log that lets me know when compression is done. When the video clips are longer around 1min this GET request never logs’=

  app.get('/clovis/api/led', function (req, res){
  
  console.log("api activated for resetLED function");
  
  resetLED();
  
  console.log("reset was completed");
  
  })

  Nodejs spawns that call different bash scripts

  function setBashScript(scriptNum){
  
  if(scriptNum == 0){
  
      //do this
  
       child = spawn('./feedmpeg.sh');
  
   resetLED();
  
  }
  
  if(scriptNum == 1){
  
      //do this
  
      updatePicturePath();
  
       child = spawn('./feedSnapshot.sh',[pictureFilePath]);
  
  resetLED();
  
  }
  
  if(scriptNum == 2){
  
      //do this
  
      updateVideoPath();
  
      child = spawn('./feedmpegRecord.sh',[videoFilePath]);
  
      isRecording = true;
  
  resetLED();
  
  ledRed();
  
  }
  
  if(scriptNum == 10){
  
      //do this
  
      updateCompressedPath();
  
       child = spawn('./generalCompressionMP4.sh',[videoFilePath,compressedFilePath]);
  
       isRecording = false;
  
   resetLED();
  
   ledBlue();
  
    }
  
    }

  generalCompressionMP4.sh - The spawn process that doesnt complete if video length is too long. Generally when the process is complete, I head over to the localhost server and view the mp4 file. When this issue occures the mp4 doesnt load, the old path is not removed, and the api doesnt send.

  #!/bin/bash
  
  FILEPATH="$1"
  
  COMPRESSIONPATH="$2"
  
  ffmpeg -i $FILEPATH -vcodec h264 -acodec mp2 $COMPRESSIONPATH
  
  sudo rm $FILEPATH
  
  curl -H "Content-Type: application/json" -X POST 
  
  http://localhost:3000/clovis/api/led

  Why might the process get stuck ? How can i fix this ? Should I not use spawn child process ?

• ctrl+c doesn't wait for child process (background process) to finish with trap

  11 avril 2019, par phisch

  I have a script which registers a SIGINT trap and starts a ffmpeg background process that records part of the screen. The SIGINT trap sends a SIGINT signal to the background ffmpeg process to get it to gracefully stop and finish the recording.

  When this script is run in a terminal, and terminated from a separate terminal with kill -INT [SCRIPT_PID], the ffmpeg background process terminates gracefully and outputs confirmation in terminal 1.

  When the script is run in a terminal and stopped with ctrl+c the background process just dies instantly. (even if ctrl+c should just send a SIGINT signal)

  Why does ctrl+c behave differently than killing the script with kill -INT in this case ?
  How can i make sure the ffmpeg background process ends gracefully when ending the script with ctrl+c ?

  #!/bin/bash
  
  
  
  exit_script() {
  
      kill -INT $ffmpeg_pid
  
      wait $ffmpeg_pid
  
      printf "\n\nffmpeg should say 'exiting normally, received signal 2' before this message is printed!\n\n"
  
  }
  
  
  
  trap exit_script SIGINT 
  
  
  
  ffmpeg -f x11grab -s 500x500 -i :0.0+0,0 ~/video_`date +%s`.webm &
  
  ffmpeg_pid=$!
  
  
  
  wait

  edit : it seems like ffmpeg receives 2 int signals in the case of ctrl+c, but i don’t know why