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I found this mp4 from the site Giphy. To my surprise it plays in Firefox. Does anyone know how that can be? Normally I have to generate two versions of every video file, mp4 and webm. It would be nice to not have to do that.

Here's the file: http://media2.giphy.com/media/yoJC2NG0MLnSoEPjIA/giphy.mp4

arpo
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2 Answers2

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Firefox will use an mp4 library is a suitable one is on the system that Firefox is running on:

Firefox/Firefox for Android/Firefox OS supports the format in some cases, but only when a third-party decoder is available, and the device hardware can handle the profile used to encode the MP4.

source

Quentin
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  • So what you say is that Firefox uses some decoder installed on my computer, a visitor without a mp4 decoder installed will not be able to play it? – arpo May 12 '15 at 11:44
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If you can use HTML5 I'd suggest the video tag like the following. I figured you'd want controls so I added the controls attribute to the video tag; you could also add autoplay if you want that. I tested it on IE11 and the current versions of Firefox and Chrome. works for all of those. Having alternate versions isn't a bad idea, but mp4 is pretty universal on modern browsers.

<video controls>
      <source src="http://media2.giphy.com/media/yoJC2NG0MLnSoEPjIA/giphy.mp4" type="video/mp4">
      <source src="http://media2.giphy.com/media/yoJC2NG0MLnSoEPjIA/giphy.webm" type="video/ogg">
    Your browser does not support the video tag.
    </video>

As to why:

MP4 H.264 (AAC or MP3) The MP4 container format with the H.264 video codec and the AAC audio codec is natively supported by desktop/mobile Internet Explorer, Safari and Chrome, but Chromium and Opera do not support the format. IE and Chrome also support the MP3 audio codec in the MP4 container, but Safari does not. Firefox/Firefox for Android/Firefox OS supports the format in some cases, but only when a third-party decoder is available, and the device hardware can handle the profile used to encode the MP4.

Note: MP4s encoded with a high profile will not run on lower end hardware, such as low end Firefox OS phones. The MPEG media formats are covered by patents, which are not freely licensed. All the necessary licenses can be bought from MPEG LA. Since H.264 is currently not a royalty free format, it is unfit for the open web platform, according to Mozilla [1, 2], Google [1, 2] and Opera. However, since royalty free formats are not supported by Internet Explorer and Safari, Mozilla has decided to support the format anyway, and Google never fulfilled their promise to remove support for it in Chrome.
Reference: https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats

Christopher
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  • Ah no I don't mean how to play it. The thing is that Firefox shouldn't be able to play MP4 since its not supported. But it can for some reason play this. – arpo May 12 '15 at 11:30
  • I'm using Windows 7 and it works, my colleague uses Mac and it worked there as well. – arpo May 12 '15 at 11:50