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webm loads completely before playing and starts playhead at the end



We are trying to figure out playback of our WebM videos in Firefox. Looking at the native video player by going directly to a video url we have some strange behavior.

We have found that the browser seems to download the entire video before beginning playback. When the video finally does download and playback, we find that often the playhead will be placed at the end of the video. If the playhead is not at the end of the video, you can't just click play, you have to click a position in the "timeline" to get the video to begin playing.

Ideally, the behavior would be that the video beings playback as it starts to download from the beginning of the file.

We are encoding the videos with FFMPEG using libvorbis and libvpx. We server our content from Amazon Cloudfront, but can also test from a lighttpd server (same behavior).

Please let me know if you would like more information and thank you for your help!

Here are a bunch of our videos to look at: http://cdn.computerscience1.net/2013/spring/lectures/1/lecture1-240p.webm http://cdn.computerscience1.net/2013/spring/lectures/1/lecture1-360p.webm http://cdn.computerscience1.net/2013/spring/lectures/1/lecture1-720p.webm http://cdn.computerscience1.net/2013/spring/lectures/1/lecture1-1080p.webm

Modified by dcoffey3296

Additional System Details

Installed Plug-ins

  • A plugin to detect whether the Adobe Extension Manager is installed on this machine.
  • Shockwave Flash 11.5 r502
  • Version
  • Google Talk Plugin Video Accelerator version:
  • iPhoto6
  • Displays Java applet content, or a placeholder if Java is not installed.
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in web pages. For more information, visit the QuickTime Web site.
  • DivX Plus Web Player version
  • DivX VOD Helper Plug-in
  • WebEx64 General Plugin Container Version 202
  • LogMeIn remote control components
  • 5.1.10411.0
  • Microsoft Office for Mac SharePoint Browser Plug-in


  • User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:18.0) Gecko/20100101 Firefox/18.0

More Information

finitarry 157 solutions 2178 answers

The video will not play right from the beginning for me. I can drag the playback marker back to the start, but when I click the play button it just zips to the end. If I move just a bit past the beginning, it will play.

Question owner

Hi All,

Thanks for the help!

FWIW, I updated our FFMPEG encoder to the latest git version and this *seems* to have fixed the problem. I will report back if we learn anything new.

ralph238 0 solutions 1 answers

Has anyone found an answer to this? I tested and used a different converter other than Miro and the issue didn't happen. The webm file played normally. Fact is, i dont want to pay for another converter - I really want to use Miro.