Ludicrous Speed, GO!

8 March, 2013 § 17 Comments

There’s another new feature in today’s build of Firefox Nightly that I want to call attention to.

In Firefox Aurora, web developers can adjust the speed that HTML5 videos are playing at using the mediaElement.playbackRate API. This API lets websites control the speed that videos play at, whether they are in slow-motion, normal, or high-speed.

Starting today in Firefox Nightly, you can adjust the speed that videos play without needing to know JavaScript. To try this out, right-click on a video and enter the Play Speed menu:

Ludicrous Speed

The menu, implemented by darkowlzz, allows the user to change the playback to one of four speeds:

I should note that there is still one remaining bug with the feature. Videos that are switched to the non-default playback speed will not switch back to Normal Speed using the context menu. This bug is on file and will need to be fixed before we can ship this feature on our Release channel. A simple workaround is to seek the video, as that will reset the playback speed.

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§ 17 Responses to Ludicrous Speed, GO!

  • Landpaddle says:


    I wish time stretching were not applied in the field of web-based audio. When an individual speeds up the content of a given video, they most likely expect the auditory component of said video to rise in pitch. Instead, the current HTML5 implementation only segments the signal into very noticeable chops.

    At least, if possible, include a context item under Play Speed that addresses this issue. A simple on/off toggle button would be great. This is really a minor nit, but for the sake of keeping Firefox flexible, something I would love to see implemented

    If my nit is purely an issue with current HTML5 standards, then I apologize in advance for not knowing more about the subject. Thank you sincerely for all the hard work.

    • msujaws says:

      Yeah, that’s definitely something that we can do. Before adjusting the playbackRate, we can set `mediaElement.mozPreservesPitch = false` which will turn off the pitch correction.

      Can you file a bug to add a toggle for pitch correction to this menu?

    • Jeff Walden says:

      I’m really not sure about “most likely expect”. Anything you want to watch faster to save time, you’re probably going to want pitch correction. Think lectures, say, where you want your semi-retired professor to speak faster so you can get through everything quicker, but you don’t want to have to work through Professor Chipmunk’s high-pitched voice. That people turn into chipmunks when played at a fast rate seems like an amusing quirk much more than something people would actively want, in most circumstances.

      I’d be surprised if people would want, or much use, a pitch-correction toggle. But I’m also not familiar enough with all use cases to say that it’s not a desirable thing to have built-in UI for.

  • Firefan says:

    The options there aren’t really useful – ludicrous indeed. I’m not sure what the right UI would be in the case, but surely you should offer more points around 1.0x. At least 1.25x.

    I’ve seen other players with this feature, they usually offer 0.1x steps, or 7% relative steps (“log steps” – 1.5x gain every 6 steps). Of course a menu with 10-15 entries might be pushing it.

    • msujaws says:

      At what point will the average user decide that advancing the video at 1.2x is better than 1.3x? Small steps like that don’t seem to provide much benefit but do cause users to have to spend more time reading the menu to find what they were looking for.

      Of course, with the API that is available you can use steps as fine-grained as you’d like. An add-on or website could provide unlimited play speeds for users.

    • Firefan says:

      msujaws: You could make a similar argument about volume control, and that ended up being a slider πŸ™‚

      0.1 steps would be too fine grained, but anybody can notice the difference between 1.0x and 1.25x, and between 1.25x and 1.5x.

    • msujaws says:

      I don’t think volume and playback speed are equal comparisons.

      Think about your TV for a moment. The volume changing on a TV may have 50 levels or more, whereas fast-forwarding and rewinding usually only has three steps in each direction (at most!).

    • Jeff Walden says:

      Yeah, there’s definitely a big difference between 1.0x and 1.5x when it comes to listening to someone speak. I find I can usually follow a lecturer easily at 1.1 and 1.2, 1.3 gets faster, 1.4 is fast but followable, and beyond that you start running into a risk of having to rewind and slow down to catch everything.

    • kcarnold says:

      Suggested menu:


  • Landpaddle says:

    Oh, yes, sure thing!

    Thanks again for the super-duper quick reply.

  • […] something that many users may request. You can read more about the new feature here on the Jaws […]

  • chuqui says:

    I have a general question… how much time do “normal” users have to wait in order to have this improvements in an official release? Thanks!

  • Gervase Markham says:

    2x is not at all Ludicrous. If you want a truly Ludicrous speed, it needs to be 5x, at least.

    • msujaws says:

      I know, right? πŸ™‚ If we set the playback rate above 4x the audio will get muted, so the best we can do is 4x. I agree that 4x would be much closer to Ludicrous Speed than our current 2x, but I think having a 2x option is important and I’m not sure of a good name for it. What do you think? (I offered Ridiculous Speed and Light Speed, but got the thumbs-down on both :D)

  • […] version of the feature. Thank you Jared and darkowlzz! (While looking for links for each, I noticed Jared posted about the new feature, check that […]

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