UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:50.0) Gecko/20100101 Firefox/50.0

Steps to reproduce the problem:
Live demo : https://jsfiddle.net/Kaiido/56rtokb8/

1. record a media (either video or audio) with MediaRcorder API
2. set the produced Blob as the source of an HTML media element
3. get the HTML media element `duration` property

What is the expected behavior?
The exact duration should be returned.

What went wrong?
`Infinity` is returned.  
However, when setting the `currentTime` to a bigger value than the real duration, `duration` returns the correct value.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version:  54.0.2840.59 (64-bit)  Channel: stable
OS Version: OS X 10.9
Flash Version: Shockwave Flash 23.0 r0
 

Deleted: /MediaRecorderBugReport.html 319 bytes

/MediaRecorderBugReport.html 319 bytes View Download