WebCodecs mp4-decode demo using mp4box.js set codedWidth/codedHeight incorrectly

[dustinkerstein]

In this demo - https://w3c.github.io/webcodecs/samples/mp4-decode - inside the mp4_demuxer.js file:

 async getConfig() {
    let info = await this.source.getInfo();
    this.track = info.videoTracks[0];

    var extradata = this.getExtradata(this.source.getAvccBox());

    let config = {
      codec: this.track.codec,
      codedHeight: this.track.track_height,
      codedWidth: this.track.track_width,
      description: extradata,
    }

    return Promise.resolve(config);
  }

this.track.track_height and this.track.track_width apparently have the DAR already applied, so they're not actually the correct codedWidth/codedHeight which can cause issues with isConfigSupported

See here for some additional background - https://bugs.chromium.org/p/chromium/issues/detail?id=1325659

[dalecurtis]

Thanks for reporting!

[dalecurtis]

@sandersdan

[sandersdan]

The correct values should come from the VisualSampleEntry.width/height (in the stsd) rather than the track metadata. It seems like mp4box.js puts this in a codec-specific place (eg. in the stsd.avc1 entry for H.264), but there is also an accessor for it at track.video.width/height.