When I choose to record to audio/ogg I do get a duration in google chrome; still no duration in firefox; and also no reset of currentTime

Tried some more debugging, but I can't seem to figure out what is going on.
I attached an image showing the stream is not seekable; I would have assumed audio/ogg is seekable.

I believe not all browsers allow using a faux HTTP Range header on XMLHttpRequest to blob URIs, which would prevent seeking. (The native audio element has no such limitation because it can get at the underlying resource.)

For Ogg, seeking is required to get the duration unless it's specified in skeleton header data (which is unlikely for audio, but possible).

Note that Safari does support range requests on blob URIs, so if you're using ogv.js as a Safari compatibility shim it should work there.

If you for some reason need to use ogv.js in Chrome and Firefox too, a possible but ugly workaround is to create a custom StreamFile-compatible object that chops up the blob with blob.slice() to read chunks, and setting that as options.stream instead of using URL.createObjectURL() and passing that into the src attribute.

Unfortunately I'm not sure I can make that transparent as there's no way I know of to get the original Blob back from the URL string; there may be though that I just haven't realized yet. :)

Ah ok, thanks. I do have the original blob. But I guess I will do things more simple ;)

getAudioPlayer(recording) {
    let player = new Audio;
    let elementCanPlayType = player.canPlayType(recording.options.mimeType);
    if (!elementCanPlayType) {
      player = new ogv.OGVPlayer();
    }
        
    player.src = recording.blobURL;
    player.type = recording.options.mimeType;

    player.ontimeupdate = (evt) => {      
      this.setState( {
        currentTime : player.currentTime,
        duration : player.duration
      } );
    }

    player.onended = () => this.stopAudio();
    return player;
  }