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Comment by drewblaisdell | Hacker News Reader

Not a comment about this specifically, but I'm a big fan of your other courses on Khan Academy. They changed the way I think about the world. I can't overstate how grateful I am that you created them.

Everyone should check out these lessons:

Journey into cryptography: https://www.khanacademy.org/computing/computer-science/crypt...

Journey into information theory: https://www.khanacademy.org/computing/computer-science/infor...

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I can't believe you just posted this. I had a 5 hour drive this morning and listened to nearly all the cryptography lectures during it.

Interesting I've been doing podcasts during my drives but never thought about Khan Academy. You can get away with not seeing anything they put on the screen or draw on a whiteboard? Have you had success with just listening to all the courses?

Hey. Is there a way to extract the audio so I can listen to it from my phone? The links above point to flash content that I can't access on mobile

There are lots of websites that will extract mp3s from youtube videos which you'll find if you just google "youtube to mp3". There are also browser extensions which do this. Here's one:

http://www.video2mp3.net/extension.php

If its android you can try this http://www.snaptube.in/

I use it for everything including X rated content from adult sites

My side project TubeSock (http://stinkbot.com/index.html) can do this for you. Just open the preferences and set it to download as MP3 or AAC.

youtube-dl can do that.

This service is neat: http://huffduff-video.snarfed.org/

It extracts the audio then "huff-duffs" it; i.e., puts it into an RSS feed you can consume with your podcatcher of choice. Check it out, it's great.

I'm a developer at Khan Academy (currently working on the upcoming Android app), and it's cool to see that there's real interest in that kind of use case! In our hackathon a few weeks ago I wrote an audio-only Khan Academy app that lets you listen to any video or the text-to-speech of any article and is controlled completely through voice commands. Unfortunately it's not quite at a point where other people can use it, but maybe I'll take the time to actually productionize it. :-)

Here's the code if you're curious:

https://github.com/alangpierce/Audicademy

And there's a feature-incomplete web version that lets you navigate to any video and play it (requires a recent version of Chrome):

https://audicademy.appspot.com

Audio only is a big thing for me. Commuting to work is a key learning time, and mostly audio is the only workable option.

That's great, thanks for posting it. And I love Khan academy, thanks for the great work. My son is 3 and I'm chomping at the bit to introduce him to Khan academy.

These videos were the main reason I grokked Diffie-Hellman during my grad CS course in crypto last year. Those are very good resources!

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