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• Fix motion blur in still frames from mpeg2video

  14 mars 2017, par Bird

  I’m extracting still frames from a video using the basic code :

  ffmpeg -i video.MXF -vf fps=1 output_%04d.png  

  In some videos, this yields images that, when the camera was moving, look much blurrier than when watching the video (see example below). The still frames from when the camera was not moving look sharper (closer to how it looks in video playback).

  The video specs are : mpeg2video, yuv422p, 1280x720 (according to FFprobe).

  Is this inherent within the video coding or structure ? The video looks so nice when in motion, but even when I pause in VLC the frame goes from sharp to blurred.

  Are there any additions to my FFmpeg code that could result in sharper images ? I tried adding a yadif filter, but it made no difference (the video isn’t interlaced anyways).

  Unfortunately I can’t post a video sample online, but below is an example of a sharper image and a blurry image ; both look in focus during video playback and are about a second apart in the video (that’s the same orange sea star on the left side).

  
  

• I can't get any error messages on node.js spawn, using ffmpeg

  21 mars 2021, par rickster26ter1

  I am trying to get the errors from a spawn process on nodejs, trying to run FFMPEG. I have not run a child process before explicitly, so I'm not sure this is right, but what I have gathered from code examples online :

  


      const {spawn} = require('child_process');
    async function(req,res){
           
    console.log(res.req.files.data[0].path);
    var tst_loc = res.req.files.data[0].path;
    try {
            var the_arr = tst_loc.split('/');
            the_arr.pop();
            tst_loc1 = the_arr.join('/') +"/test.avi";
            console.log("HERE");
            var cmd = 'ffmpeg';
                var tstspawn = spawn(cmd, [
                '-i', tst_loc,
                '-s', '800x400',
                '-b:v', '64k',
                '-c:v', 'avi',
                '-c:a', tst_loc1,
                '-o', outputfilename
            ], (error, stdout, stderr) => {
                  if (error) {
                      console.error('Error!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:', stderr);
                      throw error;
                  }
                  console.log('Success!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!', stdout);
            })
            
            tstspawn.stderr.on('data', function(data) {
            //Here is where the error output goes

               console.log('stderr: ' + data);

               data=data.toString();
               scriptOutput+=data;
            });
       

 
            tstspawn.stderr.on('error',function(error){
              console.log(error);
            });

  } catch (e) {
    console.log(e.code);
    console.log(e.msg);
  }


  


  Returns only my console logs of the path data, the console log of the "HERE", and nothing else at all. I know it didn't run properly because I do not get the expected video file that FFMPEG should have output. But I can't get any sort of error message on my console. No crashing of the application or anything...

  


  Thanks for any help,

  


• In ffmpeg command-line, how to show all filter settings and their parameters before encoding ?

  7 décembre 2023, par F.X.

  Is there a way to force the ffmpeg command-line to display a comprehensive list of all filters and their parameters, even those that are applied automatically like -vf scale ?

  


  (EDIT : To clarify, I do not mean filter documentation, but rather displaying filters that are instantiated at runtime for a particular command-line, just before transcoding starts. The goal of this is mostly checking that ffmpeg is indeed doing the right thing and not inserting/changing filters when I do not intend it to.)

  


  There are a few options available, but none are comprehensive enough. For example :

  


  

  • The lavfi module has a dumpgraph option (here) but only if you're using lavfi.

  


  • The -sws_flags print_info option (here) can be used to determine if -vf scale is applied automatically and shows a subset of its parameters, but not all of them.

  


  


  Additionally, this question appears related the answer doesn't answer what I'm looking for.

  


  Are there better ways to achieve that ?