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* Reformatted codebase using prettier.io (should not change functional behavior) * Formatted README.md, added CONTRIBUTING.md, .prettierrc configuration file, and installed pre-commit hook
89 lines
4.4 KiB
Markdown
89 lines
4.4 KiB
Markdown
# The science of accelerated playback
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**TL;DR: faster playback translates to better engagement and retention.**
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Average adult reads prose text at
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[250 to 300 words per minute](http://www.paperbecause.com/PIOP/files/f7/f7bb6bc5-2c4a-466f-9ae7-b483a2c0dca4.pdf)
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(wpm). By contrast, the average rate of speech for English speakers is ~150 wpm,
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with slide presentations often closer to 100 wpm. As a result, when given the
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choice, many viewers
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[speed up video playback to ~1.3\~1.5 its recorded rate](http://research.microsoft.com/en-us/um/redmond/groups/coet/compression/chi99/paper.pdf)
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to compensate for the difference.
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Many viewers report that
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[accelerated viewing keeps their attention longer](http://www.enounce.com/docs/BYUPaper020319.pdf):
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faster delivery keeps the viewer more engaged with the content. In fact, with a
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little training many end up watching videos at 2x+ the recorded speed. Some
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studies report that after being exposed to accelerated playback,
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[listeners become uncomfortable](http://alumni.media.mit.edu/~barons/html/avios92.html#beasleyalteredspeech)
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if they are forced to return to normal rate of presentation.
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## Faster HTML5 Video
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HTML5 video provides a native API to accelerate playback of any video. The
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problem is, many players either hide, or limit this functionality. For best
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results playback speed adjustments should be easy and frequent to match the pace
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and content being covered: we don't read at a fixed speed, and similarly, we
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need an easy way to accelerate the video, slow it down, and quickly rewind the
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last point to listen to it a few more times.
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### _[Install Chrome Extension](https://chrome.google.com/webstore/detail/video-speed-controller/nffaoalbilbmmfgbnbgppjihopabppdk)_
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\*\* Once the extension is installed simply navigate to any page that offers
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HTML5 video ([example](http://www.youtube.com/watch?v=E9FxNzv1Tr8)), and you'll
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see a speed indicator in top left corner. Hover over the indicator to reveal the
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controls to accelerate, slowdown, and quickly rewind or advance the video. Or,
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even better, simply use your keyboard:
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- **S** - decrease playback speed.
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- **D** - increase playback speed.
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- **R** - reset playback speed to 1.0x.
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- **Z** - rewind video by 10 seconds.
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- **X** - advance video by 10 seconds.
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- **G** - toggle between current and user configurable preferred speed.
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- **V** - show/hide the controller.
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You can customize and reassign the default shortcut keys in the extensions
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settings page, as well as add additional shortcut keys to match your
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preferences. For example, you can assign multiple different "preferred speed"
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shortcuts with different values, which will allow you to quickly toggle between
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your most commonly used speeds. To add a new shortcut, open extension settings
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and click "Add New".
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Some sites may assign other functionality to one of the assigned shortcut keys —
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these collisions are inevitable, unfortunately. As a workaround, the extension
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listens both for lower and upper case values (i.e. you can use
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`Shift-<shortcut>`) if there is other functionality assigned to the lowercase
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key. This is not a perfect solution, as some sites may listen to both, but works
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most of the time.
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### FAQ
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**The video controls are not showing up?** This extension is only compatible
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with HTML5 video. If you don't see the controls showing up, chances are you are
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viewing a Flash video. If you want to confirm, try right-clicking on the video
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and inspect the menu: if it mentions flash, then that's the issue. That said,
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most sites will fallback to HTML5 if they detect that Flash it not available.
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You can try manually disabling Flash plugin in Chrome:
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- In a new tab, navigate to `chrome://settings/content/flash`
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- Disable "Allow sites to run Flash"
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- Restart your browser and try playing your video again
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**The speed controls are not showing up for local videos?** To enable playback
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of local media (e.g. File > Open File), you need to grant additional permissions
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to the extension.
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- In a new tab, navigate to `chrome://extensions`
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- Find "Video Speed Controller" extension in the list and enable "Allow access
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to file URLs"
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- Open a new tab and try opening a local file, the controls should show up
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### License
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(MIT License) - Copyright (c) 2014 Ilya Grigorik
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