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• ffmpeg slows down as I run it

  14 septembre 2022, par Bambi2k21

  I edit a video such that it speeds up by 8x where the speaker is silent and by 2x when he is speaking. And to do that I use ffmpeg in such a manner :

  


  ffmpeg -i C:\Users\TheD4\Desktop\uni1.mp4 -filter_complex "[0:v]trim=0:0.98,setpts=1*(PTS- 
STARTPTS)[v0]; [0:a]atrim=0:0.98,asetpts=PTS-STARTPTS,atempo=1[a0] 
[0:v]trim=0.98:1.598,setpts=0.5*(PTS-STARTPTS)[v1]; [0:a]atrim=0.98:1.598,asetpts=PTS- STARTPTS,atempo=2[a1]; [0:v]trim=1.598:1.946,setpts=1*(PTS-STARTPTS)[v2]; 
[0:a]atrim=1.598:1.946,asetpts=PTS-STARTPTS,atempo=1[a2]; [0:v]trim=1.946:1.975,setpts=0.5*(PTS- 
STARTPTS)[v3]; [0:a]atrim=1.946:1.975,asetpts=PTS-STARTPTS,atempo=2[a3];............ 
[0:v]trim=1529.04:1537.34,setpts=1*(PTS-STARTPTS)[v1652]; [0:a]atrim=1529.04:1537.34,asetpts=PTS- 
STARTPTS,atempo=1[a1652]; [0:v]trim=1537.34:1537.55,setpts=0.5*(PTS-STARTPTS)[v1653]; 
[0:a]atrim=1537.34:1537.55,asetpts=PTS-STARTPTS,atempo=2[a1653]; 
[0:v]trim=1537.55:1538.73,setpts=1*(PTS-STARTPTS)[v1654]; [0:a]atrim=1537.55:1538.73,asetpts=PTS- 
STARTPTS,atempo=1[a1654]; [0:v]trim=1538.73:1539.15,setpts=0.5*(PTS-STARTPTS)[v1655]; 
[0:a]atrim=1538.73:1539.15,asetpts=PTS-STARTPTS,atempo=2[a1655]; [v0][a0][v1][a1][v2][a2][v3] 
[a3]..........[v1652][a1652][v1653][a1653][v1654][a1654][v1655][a1655]concat=n=1656:v=1:a=1" -preset 
superfast -profile:v baseline


  


  But the thing is, as you might have noticed the filter goes into the thousands, and so the total number of caracters is high(in this example there are around 200000), but cmd(8000) or powershell(30000) have less than that. So to get around that limitation, I divided all of that into smaller parts, but here is where the problem starts, as I run more and more of the "parts code" and ffmpeg does work on later and later parts of the video, the process of making the video from those smaller parts becomes slower as well, even though the size of the video is the same. To see what is wrong, I ran the code from a couple of hundred seconds(so instead of starting from 0s it start from let's say 500s) and I noticed the same effect. So what I think happens is that ffmpeg goes through the entirety of the video until it reaches the specified start. So here is my question is there a way to tell ffmpeg to ignore the start of the video and to start immediately from where I need it to, maybe something like this :

  


  ffmpeg -i C:\Users\TheD4\Desktop\uni1.mp4[500:] -filter_complex ........


  


• avcodec : add a subcharenc mode that disables UTF-8 check

  24 mars 2018, par wm4

  avcodec : add a subcharenc mode that disables UTF-8 check
  This is for applications which want to explicitly check for invalid
  
  UTF-8 manually, and take actions that are better than dropping invalid
  
  subtitles silently. (It's pretty much silent because sporadic avcodec
  
  error messages are so common that you can't reasonably display them in a
  
  prominent and meaningful way in a application GUI.)
  

  • [DH] doc/APIchanges
  • [DH] libavcodec/avcodec.h
  • [DH] libavcodec/decode.c
  • [DH] libavcodec/options_table.h
  • [DH] libavcodec/version.h

• How to Kill ffmpeg process in node.js

  15 janvier 2023, par Sanjay

  I am using node.js code that convert Axis Ipcamera live stream into mp4 using FFMPEG

  



   var childProcess=require('child_process');
 var childArguments = [];
var child=[];
var cmd='ffmpeg -i rtsp://172.24.22.117:554/axis-media/media.amp -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -preset slower -crf 18 -vf "scale=trunc(in_w/2)*2:trunc(in_h/2)*2"'+' '+__dirname+'/uploads/ouput.mp4';

  child=childProcess.exec(       
        cmd,
        childArguments,
        {            
            env: process.env,
            silent:true
        },  function (err, stdout, stderr) {
            if (err) {
                throw err;
            }
            console.log(stdout);

        });     

        //    here generate events for listen child process (works properly)
    // Listen for incoming(stdout) data
    child.stdout.on('data', function (data) {
        console.log("Got data from child: " + data);
    });

    // Listen for any errors:
    child.stderr.on('data', function (data) {
        console.log('There was an error: ' + data);
    });

    // Listen for exit event
    child.on('exit', function(code) {
        console.log('Child process exited with exit code ' + code);
        child.stdout.pause();
        child.kill();
    });


  



  my above code works perfectly. It gives the output as I want, but I am not able to kill(stop) the ffmpeg command. I am using the code below for stopping the process, but in background it still continues.

  



  child.kill("SIGTERM"); 


  



  I also used following commands : child.kill('SIGUSR1') ; child.kill("SIGHUP") ; child.kill("SIGINT") ;child.kill('SIGUSR2') ; for killing this process but it not works.

  



  Currently I forcefully kill the node application to stop ffmpeg command and generate mp4 file. I do not want this.
But I want commands that stop ffmpeg process and generate mp4 file, without killing the node application.