Error Correction - Computerphile

What good is knowing you have a problem if you can't fix it? - Professor Brailsford explains Hamming Codes and how errors can not just be detected, but also corrected.

This video was filmed and edited by Sean Riley.

[ArrayPro]

I could seriously sit and listen to this guy all day, he's so goddamn interesting.

[AlexanderBollbach]

only issue i have with this channel is the videos that are part of a series of videos are not labeled.  Sometimes you give them the  "continued.." but that doesn't help if there are more than 2.

[damiensadventure]

Professor Brailsford is video GOLD for education about this field and it's history!

[JMPDev]

Definitely my favorite series on computerphile so far!

Would love it if we could venture further into the 'hairy' stuff, even if we'd only scratch the surface in such a short format :)

[SharpblueCreative]

Different idea in cd error correction Reed Solomon I believe in 1960s - love to see him demonstrate that correction code. If memory serves a 16x16 grid. Though it's years since I studied theory.

[steve]

It'd be great if we could have "Part 1" and so on in the title, I often stumble onto Part 2 from a video that interested me, without knowing it'd been there

[aafaqin]

this channel ND numberphile i love it.. 
i am doing my computer engineering and sometimes when i get frustrated of my hectic life schedule and want a productive break these are the two channels i come to...
i hope you guys make more and more videos .. so that it can make  my course more interesting and also encourage young minds to perceive career in computer also it would help ordinary people to know how the devices they use so casually work...
guys please make more videos... i love them all and it makes my course really more interesting ...

[AlexN]

Just programmed a hamming encoder/decoder for my programming class! Really cool stuff, I'd like to learn how multiple bit error detection/correction works

[RobbieMelvin]

Flashbacks to 12 months ago. and my grad course. This is one of the foundation pieces guys! Can't have our lovely wi-fi without it.

[hellterminator]

You should make a video about creating Hamming codes for larger numbers/multiple errors. You said it was very complicated but I disagree. It is one of the simpler algorithms, it is absolutely beautiful and anyone who ever took algebra should be able to understand it. 

[Ykulvaarlck]

I'm feeling proud that I know what he was talking at the end.

[TorgieMadison]

Why use the cube at all?  Why over complicate this?  If you got two zeroes, it's an ACK.  If you got two ones, it's a NAK.

The point is that, minus the perfect 000/111 case, you're tolerating at most one bit of corruption.  So  110, 101, 011 = the only possible ways to corrupt one bit of three ones.  Likewise, 001, 010, 100 = the only possible ways to corrupt one bit of three zeroes.

Keep It Simple, Smarty.

[ThatAnnoyingGuyFrom]

To break down a concept an demonstrate it in basic terms it's always good to go back many generations before modern error correction algorithms for example like the streaming video data in this video.

[AaronCZim]

This is my favorite series in computerphile so far.

[AlexanderTrefz]

I have to say that in general the computerphile videos are not all that interesting to me (a programmer), which suprised me a lot because i liked the idea. But the videos with Professor Brailsford are always really really good and i feel they are explained well even for those that are not that deeply familiar with the things he talks about. Keep it up!

[elliottmcollins]

As he mentioned at the end, modern error correction methods are based on sophisticated versions of this method. This channel is more about the origins and foundations of CS than about teaching cutting edge methods.

[lmpeters]

RAID 1 and 10 have error correction in that there's at least one identical copy of everything. RAID 4 and 5 reserve one disk's worth of space to store parity bits (which follow the same rules that Professor Brailsford has been describing), and if one disk fails, you can use those parity bits along with the contents of the surviving disks to figure out what would have been on the disk that failed.

[yvrelna]

The arrangement of bits in that cube has a very special property that makes the detection possible, notice how every sides in the cube connects two points that differs in exactly one bit. The cube looks a little pointless here because there's only 3-bits, but with larger number of bits, when you're sending n-bits with larger correction distance, you can construct an n-dimensional hypercube to help visualize and correction simply becomes finding the nearest "good neighbors" in the hypercube.

[Jenny_Digital]

I was working on sending small packets of no more than 256 bytes of data over IR using a a NRZ scheme really meant for TV remotes. I wanted good error correction but I think a few braincells upped and left me in the effort. I had to settle for error detection only in the end. Excellent work and thumbs up!

[pcljet]

First, it actually is possible to have signals with different lengths (look up "variable-length code" for some examples).
Second, a "0" signal is not the absence of power, because then a "1" signal would be indistinguishable from a "01" signal or a "10" signal. A "0" signal would be a low-voltage signal and a "1" signal would be a high-voltage signal (or some other representation of what is technically a 3 character language with "no power" being a "space" or null character).