Firefox 49: set default HTML5 video volume

Martin Brinkmann
Jun 4, 2016

Mozilla has added a new feature to Firefox 49 -- currently available if you run Firefox Nightly -- that allows you to set a default HTML5 video volume in the browser.

While it is usually possible to change the volume of audio or video content using an interface that is provided on sites, browsers usually don't provide you with options to change the default volume.

Other options may be available, for instance on Windows where you can change the volume of Firefox or whichever browser you are using to adjust the volume of audio this way.

Some sites may remember the volume setting and use it from that moment on automatically (until you clear cookies or whichever system they are using to store the information).

One of the issues with web audio, and it is the same with audio on TV, is that different shows, movies or advertisement may use different noise levels.

Advertisement is usually louder than other content, but if you look at a site like YouTube, you will encounter videos that are louder or quieter than others.

Setting the default HTML5 video volume in Firefox

firefox default volume

Firefox 49 ships with a new setting that allows you to adjust the default volume of HTML5 videos in the browser.

Please note that this may not work on all sites using HTML to stream video content to your device. It has no effect on YouTube for instance currently while it works fine when HTML 5 videos are played directly in Firefox without custom player interface.

To change the default volume in Firefox, do the following:

  1. Load about:config in the browser's address bar.
  2. Confirm that you will be careful if this is the first time you open the configuration screen.
  3. Search for the preference media.default_volume.
  4. It's default value is 1.0 which equates 100% volume.
  5. Double-click on the line and a prompt should appear.
  6. Use it to change the value using the same system, e.g. 0.1 for 10%, or 0.6 for 60%.

Firefox will use the new default volume for HTML5 videos on all supported pages from now on. You can test this by opening a video page like this one to see the result right there.

It is unclear right now whether Mozilla will implement an option to change the volume on Firefox's options page, or if the preference will be the only option to change the volume. If the latter is the case, it probably will remain a good kept secret that barely anyone knows about. (via Sören)

Now You: What's your take on the volume of web video?

Firefox 49: set default HTML5 video volum
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Firefox 49: set default HTML5 video volum
Mozilla has added a new feature to Firefox 49 -- currently available if you run Firefox Nightly -- that allows you to set a default HTML5 video volume in the browser.
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  1. Annabelle said on April 25, 2020 at 7:52 pm

    I wonder if there’s a way one can change the default device that audio outputs from Firefox. Something like “”, then a dialog box appears, with a list of whatever devices are on your computer, where one can choose which device they would like to hear audio in Firefox.

  2. VanguardLH said on August 22, 2019 at 11:44 pm

    Youtube somehow (probably via scripting) gets around the HTML volume control setting using Firefox’s media.default_volume setting. They manage to start their videos at 100% for the control’s volume setting. Using media.volume_scale will help by reducing the initial volume, say, down to 50% (0.5), so you aren’t blasting high volume through your speakers. However, that affects all videos. I find the 100% scale too high for almost every video, and I don’t want to change my speaker volumes for videos which makes all other sound events events in Windows too soft.

    While the scale setting does reduce the volume level, it doesn’t seem linear; however, they might doing a linear change in volume but human ears hear logarithmically. Still, it provides a volume reduction that not even Youtube will override.

    Yet, many videos from elsewhere become too soft when scaling it used globally. Too bad Mozilla has not added volume scaling as a per-site preference. Then you could reduce volume at Youtube, and for other often visited too-loud sites, but leave it 100% at other sites.

  3. Anonymous said on October 11, 2018 at 5:41 pm

    media.volume_scale is a related preference in about:config to adjust the volume. You can use it to make every video louder/quieter.

  4. Anonymous said on October 11, 2018 at 5:40 pm


  5. Sylvio Haas said on January 20, 2017 at 8:54 pm

    Hello, Martin!
    Happy 2017!

    Ref. item 6. Use it to change the value using the same system, e.g. 0.1 for 10%, or 0.6 for 60%.
    I’m not sure I understood it well. Does this mean that if I want a 50% volume increase I have to change the prompt from the actual 1.0 to 1.5?
    (My browser is Firefox 50.1.0)

    Thank you

    1. Martin Brinkmann said on January 21, 2017 at 7:32 am

      Yes that is correct Sylvio.

      1. Sylvio Haas said on January 21, 2017 at 12:24 pm

        Thank you!!

  6. drop said on June 4, 2016 at 9:11 pm

    don’t all firefox have volume control on the default player? if I need to change volume the just reduce it manually.
    if you change the volume, it will be saved the next time you load a video(becomes default volume).
    works on youtube player and default player.

    1. Dave said on June 6, 2016 at 1:02 pm

      Videos are created at different volumes, and therefore playback at unpredictable volumes. Volume setting 1 for one video can be the same as volume setting 9 for another. I’m not even going to bother explaining why normalised volume is better that the chaos that we have had up until now.

  7. Mark Hazard said on June 4, 2016 at 8:29 pm

    I am happy that I can turn the sound off on those auto-play HTML5 videos in Firefox. They used to drive me crazy.
    I am still on Firefox 46, so it will be some time before I will get this new feature, but I look forward to it. I don’t like using beta software, as borne out with my recent experience with Vivaldi 1.2 64 bit. I stay on the stable channel.

    I can control the volume of YouTube videos with my mouse wheel on Opera with the “Magic Actions for YouTube Video” extension. I couldn’t find this extension on Firefox.

    1. nobody said on June 5, 2016 at 8:43 am

      On Firefox you can use which can control the volume with mouse and can do a lot more.

  8. slowpoke said on June 4, 2016 at 7:49 pm

    several years after tag was introduced, mozilla corp. finally adds such unbelievable feature that took thousands lines of code to implement!
    oh, i’m so exited to use such awesome app!

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