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• Windows Pipes STDIN and STDOUT Parent Child proc communication IPC FFMPEG

  15 octobre 2018, par Evren Bingøl

  I am writing a simple WINDOWS app which demonstrates piping,

  I pass byte size data down to child proc, increment the value and send the char size data back to parent and loop until it reaches MAX_CHAR
  Pretty much demonstration of "i++" with IPC.

  Parent Process

  while(i<256){
  
      bSuccess = WriteFile(g_hChildStd_IN_Wr, chBuf, sizeof(char), &dwWritten, NULL);
  
      bSuccess = ReadFile(g_hChildStd_OUT_Rd, chBuf, sizeof(char), &dwRead, NULL); // IF THERE IS NO FFLUSH IT BLOCKS
  
  }

  And in Child

  while (i<256){
  
          byte data=0;
  
          fread(&data, sizeof(char), 1, stdout);
  
          data++;
  
          fwrite(&data, sizeof(char), 1, stdout);
  
          //fflush(stdout); IF I DO NOT HAVE THIS  PARENT BLOCKS ON READ
  
  }

  First of all if I do not FFLUSH child proc stdout, the parent blocks on reading child’s stdout.

  How can one run this code without having to fflush child’s stdout.

  Closing the pipe after child’s first write is not an option as it is in a loop and needs to execute 256 times.

  more generically I want the child to write N bytes to parent, parent read that N bytes do something and write back to child another N bytes and child does something with that N bytes and write to parent N bytes. This happens M times.

  thing is I can not use fflush because my final goal is to use a child process that is not implemented by me.

  My final goal is to pipe data to FFMPEG encode the data and read back from the stdin and do this over and over again with out having to fork a new FFMPEG process for each image frame but rather fork one instance of FFMPEG and pipe data in and read data out from it. And since I did not implement ffmpeg and I can not change the source code.

  thanks

  Thanks

• 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)

• avformat/hls : copy rw_timeout from parent to child AVIOContexts.

  17 avril 2018, par Steven Liu

  avformat/hls : copy rw_timeout from parent to child AVIOContexts.
  The rw_timeout option is currently not applied when opening media playlist,
  
  segment, or encryption key URLs. This can cause the HLS demuxer to block
  
  indefinitely, even when the rw_timeout option has been specified. This change
  
  simply enables carrying over the rw_timeout option when the demuxer opens these
  
  URLs.
  Reviewed-by : Steven Liu <lq@chinaffmpeg.org>
  
  Signed-off-by : Richard Shaffer <rshaffer@tunein.com>
  

  • [DH] libavformat/hls.c