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Comment by blt | Hacker News Reader

Do you have details? I noticed that Youtube on Firefox makes the fan spin up on my 2013 rMBP a lot. I currently use Firefox but as a heavy Youtube watcher this is a pretty big negative.

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Same here. I have been a longtime Firefox user and don't recall having performance issues with YouTube on macbook before Quantum. But now if I'm watching anything more than a short clip on YouTube, the MBP's fans start to annoy me and it feels like it is going to burn a hole in my lap. YouTube in Chrome is totally fine. YouTube on Firefox on my Windows Intel NUC desktop is also totally fine. It seems to be a mac only Firefox issue. Would really love a solution!

Firefox uses H.264 for YouTube on macOS, so it can use the system's H.264 hardware decoder, which should be faster and use less power than a software decoder. Chrome uses a VP9 software decoder on YouTube. You can try VP9 in Firefox by setting the about:config pref "media.mediasource.webm.enabled" = true, but it is disabled by default for good reasons. :)

This YouTube page will show which codecs are currently enabled in your browser: https://www.youtube.com/html5

This is because Youtube pushes VP8/VP9-encoded video by default to save on bandwidth. Unfortunately, absence of a hardware decoder consumes a ton of battery. Both Firefox and Chrome receive VP9 encoded video.

Safari doesn't understand VP9. So Youtube pushes H.264 video which can be hardware accelerated.

To force youtube to send H264 in firefox/chrome you need something like https://addons.mozilla.org/en-US/firefox/addon/h264ify/

Firefox uses H.264 for YouTube on macOS, so it can use the system's H.264 hardware decoder.

This YouTube page will show which codecs are currently enabled in your browser: https://www.youtube.com/html5

Same here, if I'm watching YouTube on my 2015 rMBP I have to use Safari rather than Firefox if I don't want the fans to spin up.

Yeah I’ll dig up he bugzilla link and add to this comment.

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