Recherche avancée

Sur d’autres sites (6821)

• Change video resolution in loop

  24 juillet 2020, par WoJo

  I am trying to decrease the resolution of a video to under 500x500. I don't want to change it to exactly 500x500 because that would mess up video quality. So what I am trying to do is to decrease the resolution by 75% in a loop, and that loop would only stop when the video is under 500x500. In theory that would not be hard, but I can't seem to figure it out.

  


  var vidwidth = 501; //Create variable and put it to 501
var vidheight = 501; //so that it won't go through the If Statement
fs.copyFile(filepath2, './media/media.mp4', (err: any) => { //Copy given file to directory
    console.log('filepath2 was copied to media.mp4'); //Log confirmation (Not appearing for some reason, but file is copied)
})
while (true) {
    getDimensions('./media/media.mp4').then(function (dimensions: any) { //Get dimensions of copied video
        var vidwidth = parseInt(dimensions.width)   //Parse to Int
        var vidheight = parseInt(dimensions.height) //and put in variables
    })
    ffmpeg('./media/media.mp4')                 //Call ffmpeg function with copied video path
        .output('./media/media.mp4')            //Set output to the same file so we can loop it
        .size('75%')                            //Reduce resolution by 75%
        .on('end', function() {                 //Log confirmation on end
            console.log('Finished processing'); //(Not appearing)
        })                                      //
        .run();                                 //Run function
    if (vidwidth < 500 && vidheight < 500) {    //Check if both the width and height is under 500px
        break;                                  //If true, break the loop and continue
    }
}


  


  This is the current code I am using with comments. Basically what happens is it gets stuck in the while loop because the dimensions of the video won't change. Tested with console.log() line. I think that if I can fix the ffmpeg problem somehow it will all be fixed.
I'd appreciate any help :)

  


  PS : This is all made in typescript, then build into js using npx tsc

  


• Have ffplay output current time in millisecond resolution

  21 août 2020, par 12.yakir

  What are the arguments for ffplay to output the duration/time-stamp of the current frame in millisecond resolution (dumping it to stderr or stdout, not embedding or overlaying it into the video) ?

  


  Right now playing a video (and pausing it) will look like this :

  


  ~$ ffplay -i video.mp4 -hide_banner -loglevel 8 -stats
   2.09 A-V: -0.004 fd=   6 aq=   31KB vq=   84KB sq=    0B f=0/0


  


  Note that the current time, 2.09, is in "centi-seconds" (one hundredth of a second), not millisecond (one thousandeth of a second).

  


  Ideally, it would output only the current time in millisecond resolution :

  


  ~$ ffplay -i video.mp4 -hide_banner -loglevel 8 -stats <enter magic="magic" arguments="arguments" here="here">&#xA;   2.093&#xA;</enter>

  


• Is variable resolution possible in MPEG-4 or Matroska ?

  29 août 2020, par Chris_F

  It's become increasingly common for movies to contain sections with varying aspect ratios. For instance, the movie The Dark Knight is is sometime 16:9 full frame, and at other times 2.40:1 with letter boxing. This is fine when viewed on a 16:9 (or even 4:3) screen, but if you try to watch it on a 2.40:1 screen you will get simultaneous horizontal and vertical letterboxes. Extremely undesirable.

  


  Currently I use MPC-HC, which has a feature where it is able to analyze the video in real time, detect letter boxing, and dynamically crop the video. This works pretty well, but it's kind of an ugly solution. Are there any video formats that allow meta data like image resolution to change throughout the video ?