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• 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

  


• The other shoe drops

  13 octobre 2009

  Sure enough, Apple has announced iMovie 8.0.5 with support for the iFrame format. I win the prize !

• Trying to crop an image in ffmpeg using alphamerge but produces wrong alpha

  12 septembre 2021, par Alex Styl

  I am using alphamerge in order to crop an image within a circle.

  


  What I have so far is :

  


  ffmpeg -f lavfi -i "color=c=white:size=240x240" -i avatar.png -i mask.png -filter_complex \
 "[1][2]alphamerge[img]; \
 [0][img]overlay[out]" -c:v png -map "[out]" -pix_fmt rgba -t 5 -y out.mp4 2>&1


  


  with avatar.png and mask.png respectively being :

  


  

  


  This produces the following output (1 frame of the output video) :

  


  

  


  which is unexpected, given the original input is much darker than this.

  


  How can I crop the 'avatar.png' using the 'mask.png' so that the output is the avatar.png cropped in a circle and keeping the same alpha ?

  


  PS : The important bit here is for me to be able to crop the original image and maintaining the correct colors/apha of the original image. If there is an other way of doing this (other than alphamerge) I am happy to hear it.