VideoWidth and VideoHeight are not recieved correctly on getting loadedMetadata Event

By design Issue #12713373


Jul 11, 2017
This issue is public.
Found in
  • Microsoft Edge
  • Internet Explorer
Reported by 1 person

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Steps to reproduce

When using Media Source Extensions for playing MP4 content, we are not getting VideoWidth and VideoHeight correct on recieving loadedMetadata Events.
According to the spec, we should get loadedMetadata event when dimensions of the media Resource has been determined.

On Chrome and Firefox, we get correct values for the videoWidth and VideoHeight.

Here is the sample Script file to demonstrate the same.
The media file has dimensions width= 1024 and height =436 but we get width=1920 and height =1080.


Comments and activity

  • Changed Steps to Reproduce

  • Microsoft Edge Team

    Changed Assigned To to “James M.”

  • Hello,

    Thank you for providing this information about the issue. After thorough testing, we are unable to reproduce this problem in Edge. A screenshot is attached to show our results. Please test this behavior in our latest creator’s update 15063 or the insider build 16232.

    Best Wishes,
    The MS Edge Team

  • I am using Microsoft Edge 38.14393.0.0 on WIndows 10.
    I have attached the logs screenshot for Edge also.

  • Microsoft Edge Team

    Changed Assigned To to “Venkat K.”

    Changed Assigned To from “Venkat K.” to “Nishant N.”

    Changed Assigned To from “Nishant N.” to “Stephen E.”

    Changed Assigned To from “Stephen E.” to “Rafael V.”

    Changed Status to “By design”



    Thank you for contacting us about this issue and letting us know that Edge has different output than Chrome/Firefox for this. However, we are resolving this bug as ‘by design’ for now. The MSE spec ( does not mention any explicit requirement about this. The HTML spec holds true for progressive download content, in which the dimensions must be determined after the onmetadataloaded event, but not MSE content.

    We dynamically update the dimensions of the MSE video source after we have read the first frame, for a variety of reasons including lowering latency and minimizing battery usage. This is why you are encountering the initial 1920 x 1080 resolution, prior to the first frame being read. Due to the nature of MSE’s dynamically changing content, we update the dimensions accordingly as needed.

    MS Media Playback team

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