Blob video duration metadata [duplicate]

Question

This question already has an answer here:

• How can I add predefined length to audio recorded from MediaRecorder in Chrome? 3 answers

I am writing a software that manipulates camera stream video in firefox.

I am generating a Blob with video type recorded with MediaRecorder API.

What i am doing to save the blob as video in local storage is using FileSaver library :

    FileSaver.saveAs(BlobVideo,"video.mp4");

It seems the video doesnt have any max duration, so i cannot navigate in timeline in my newly generated video in VLC, for example.

Is there a way to set duration metadatas on a blob video?

Answer 1

This question is an almost duplicate of this other one. _{(But since there is a bounty on it, we can't vote to close)}

This is a known chrome bug.

You can have this duration from the browser itself by loading the video, setting its currentTime to some extra-value, then reading the duration, but you won't have it attached to the file itself, at least not until the bug has been fixed.

Answer 2

Until the chrome bug that Kaiido mentioned gets fixed, this worked for me:

while(video.duration === Infinity) {
  await new Promise(r => setTimeout(r, 1000));
  video.currentTime = 10000000*Math.random();
}
let duration = video.duration;

It would probably be a better idea to listen for the "durationchange" event though, rather than having the arbitrary 1 second pauses.