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• Ffmpeg output stream closed

  29 novembre 2023, par excalibur

  There is one problem in my code that uses ffmpeg to convert webm videos to mp4 and set duration to 10 seconds, it works well but, sometimes returns "output Stream closed" error. What can be a reason of this problem, and how can i solve it ?

  


  My code :

  


  async convertWebmVideoToMp4(buffer: any) {
    try {
        return new Promise((resolve, reject) => {
            const videoMp4Buffer = Buffer.from(buffer);

            const readable = Readable.from(videoMp4Buffer);

            const outputBuffer = [];

            const outputStream = new Writable({
                write(chunk, encoding, callback) {
                    outputBuffer.push(chunk);
                    callback();
                },
            });

            const ffmpegProcess = ffmpeg()
                .input(readable)
                .outputFormat('mp4')
                .videoCodec('libx264')
                .audioCodec('aac')
                .duration(10)
                .outputOptions([
                    '-movflags frag_keyframe+empty_moov',
                    '-preset ultrafast',
                    '-c:a aac',
                    '-r 30',
                    '-tune fastdecode',
                ])
                .on('end', () => {
                    outputStream.end();
                    const finalOutputBuffer = Buffer.concat(outputBuffer);
                    resolve(finalOutputBuffer);
                })
                .on('error', (err, stdout, stderr) => {
                    console.error(err);
                    reject(err);
                });

            outputStream.on('error', err => {
                this.logger.error(err);
            });

            ffmpegProcess.pipe(outputStream, { end: true });
        });
    } catch (error) {
        throw error;
    }
}


  


  My code should return the buffer of video that type is mp4 and length is 10 seconds, but it returns "output stream closed" error.

  


• How to stop perl buffering ffmpeg output

  4 février 2017, par Sebastian King

  I am trying to have a Perl program process the output of an ffmpeg encode, however my test program only seems to receive the output of ffmpeg in periodic chunks, thus I am assuming there is some sort of buffering going on. How can I make it process it in real-time ?

  My test program (the tr command is there because I thought maybe ffmpeg’s carriage returns were causing perl to see one big long line or something) :

  #!/usr/bin/perl
  
  
  
  $i = "test.mkv"; # big file, long encode time
  
  $o = "test.mp4";
  
  
  
  open(F, "-|", "ffmpeg -y -i '$i' '$o' 2>&1 | tr '\r' '\n'")
  
          or die "oh no";
  
  
  
  while(<f>) {
  
          print "A12345: $_"; # some random text so i know the output was processed in perl
  
  }
  
  </f>

  Everything works fine when I replace the ffmpeg command with this script :

  #!/bin/bash
  
  
  
  echo "hello";
  
  
  
  for i in `seq 1 10`; do
  
          sleep 1;
  
          echo "hello $i";
  
  done
  
  
  
  echo "bye";

  When using the above script I see the output each second as it happens. With ffmpeg it is some 5-10 seconds or so until it outputs and will output sometimes 100 lines each output.

  I have tried using the program unbuffer ahead of ffmpeg in the command call but it seems to have no effect. Is it perhaps the 2>&1 that might be buffering ?
  Any help is much appreciated.

  If you are unfamiliar with ffmpeg’s output, it outputs a bunch of file information and stuff to STDOUT and then during encoding it outputs lines like

  frame=  332 fps= 93 q=28.0 size=     528kB time=00:00:13.33 bitrate= 324.2kbits/s speed=3.75x

  which begin with carriage returns instead of new lines (hence tr) on STDERR (hence 2>&1).

• ffmpeg x11grab moov atom not found

  30 mars 2021, par Jintor

  2 FFMPEG process

  


  (1) generating a ffmpeg x11grab to a .mp4
(2) take the .mp4 and restream it simultaneously to multiple rtmp endpoints

  


  ISSUE the generated file in (1) have this error "moov atom not found"

  


  This is the command that generate (1) :

  


  ffmpeg -re -y -f x11grab -draw_mouse 0 -framerate 30 
-video_size $RESOLUTION -i :$DISPLAY_NUM -c:a aac -c:v libx264 
-movflags +faststart -preset ultrafast -crf 28 -refs 4 -qmin 4 
-pix_fmt yuv420p -filter:v fps=30 file.mp4


  


  in the (2) => when I try to ffmpeg -i file.mp4 output somewhere : I get "moov atom not found" so the (2) can't read or open (1).

  


  What I'm I missing

  


  in (1) -movflags +faststart doesn't seem to fix the issue

  


  ••••••• EDIT : more details on the context ••••••

  


  I'm using openvidu : webrtc with kurento and coturn.

  


  The record feature creates a .mp4 on the fly as the chat is going on.

  


  To start the recording, there is an API call i can make to my server and it automatically stops when all users leaves the chatroom OR do an other api call to stop. see composed video in this link https://docs.openvidu.io/en/2.17.0/advanced-features/recording/

  


  openvidu have also webhooks.

  


  My problem is not how to stop ffmpeg, but getting FFMPEG to encode while the mp4 or other is being generated "on the fly".

  


  There is 2 options :

  


  OPTION 1 : individual => 1 .webm per camare => this .webm ffmpeg can restream as hls or RTMP => it's working.

  


  OPTION 2 : ** but the issue is with "Composed" video => it's using ffmpeg to x11grab the session... but it's mp4 without moov ato, so ffmpeg don't do anything with this.

  


  see the composed.sh script here
https://github.com/OpenVidu/openvidu/blob/master/openvidu-server/docker/openvidu-recording/scripts/composed.sh