Bram Cohen Interview

BitTorrent is now a beast with two heads: it’s widely used by anyone and everyone with a large file to share, but it’s also an application that’s becoming a Hollywood favourite. P2pnet interviewed Bram Cohen, the mastermind behind BitTorrent

p2pnet: Hi, Bram. I know you must be up to your ears in alligators and I really appreciate you taking the time out to answer these questions, particularly since I realise some of them are a little on the thorny side.

p2pnet: Did you ever think BitTorrent would take off in quite the way it has?

Cohen: I’ve run out of answers to give to that question. Yes? No? Maybe?

p2pnet: When was the very first time you actually saw what was to become BitTorrent as a workable application?

Cohen: It first had the current user interface in early 2002. It first transferred files with the current protocol format and not for testing in late 2002.

p2pnet: If you could travel back in time, is there anything you’d change about the BT technology?

Cohen: A few little things, for example some protocol extensions which we’re about to unveil which are the way things should really have been done to begin with, but in terms of what the pieces are and how they interact, I think I did it right.

p2pnet: How does it feel to realize that not perhaps, but definitely, your children will read about you in the history books as someone whose invention quite literally changed the face of the Net and world comunications?

Cohen: My children seem happy with me just as daddy.

p2pnet: What achievement, or achievements, are you most proud of?

Cohen: I’d say getting BitTorrent to be such a compelling tool that publishers started using it, despite massive political pressure not to. The Linux distro torrents were quite amusing until the Linux distros got sick of being humiliated and started doing them themselves.

p2pnet: What kind of computer equipment do you use?

Cohen: Currently, an IBM laptop running Ubuntu. It’s okay, but playing video files is quite busted.

p2pnet: What’s you favourite piece of software?

Cohen: That’s rather like asking what one’s favorite type of weld is. People use software to get stuff done, not for the sake of playing with software. The exception is games, but I haven’t had much time for game playing lately.

p2pnet: What’s your personal favourite piece of code?

Cohen: You mean of my own? I generally want to rewrite everything after it’s been around for a while, so it’s hard for me to get too excited about any one thing. The merge code I wrote recently is rather nice though, since it’s simple enough that people can experiment with it and try out variations, while historically merging has been so difficult that it’s almost unapproachable.

p2pnet: You use Ubuntu. So what do you like about it?

Cohen: Uh … it’s less likely to get hacked than windows?

p2pnet: Would you recommend Ubuntu to anyone (or everyone : ) ?

Cohen: Not until it plays all video properly out of the box and has a good working UI for selecting wireless networks. Both of those work poorly on windows too though.

p2pnet: If not, what would you recommend?

Cohen: Flint tools rarely have such problems.

p2pnet: What kind of music do you listen to, and where do you get it?

Cohen: I haven’t had much time for music lately. In my early 20’s I bought close to 1000 CDs, which are quite eclectic in style, but I did used to listen to a lot of industrial music.

p2pnet: What’s your favourite, and least favourite, movie?

Cohen: Someone asked me what my favorite movie was a few years ago, and I said Blade Runner, and she said Everybody says Blade Runner, and asked for a different movie, so I guess the right answer is Amadeus. As for least favorite, that’s hard to say, so many things are unwatchably bad.

p2pnet: What was the very first computer you ever had and where did it come from? And what did you use it for?

Cohen: A Timex Sinclair in 1980. I used to write little programs in basic to make it crash, for example by poking into random parts of memory or doing an infinite recursion.

p2pnet: How old were you?

Cohen: Five.

p2pnet: Can you remember the first program you ever wrote? And how old were you then as well?

Cohen: The first substantive program I even wrote was when I was 12, and it played connect 4, written in Promal on my Commodore 64. I wrote a simple board evaluation algorithm and alpha-beta pruning. It could stomp me quite thoroughly.

p2pnet: Putting BT to one side, which do you think is the most significant commercial p2p application out there at the moment?

Cohen: In terms of a commercial entity publishing their own content, there isn’t a significant competitor to BitTorrent protocol, nor is there a need for one. That problem has been solved.

Ap2pnet: And on the indie p2p side, what impresses you the most?

Cohen: There’s been some interesting work on DHTs.

p2pnet: What would you think about replacing BitTorrent trackers with virtual trackers in a DHT network?

Cohen: A tracker is both more reliable and lets you get statistics about distribution. The reasons to not use one are for (massive) scaling and reliability, which are rarely ever a problem. We do have a DHT protocol though, and it works quite well.

p2pnet: You’re the co-founder of CodeCon. Are you still involved?

Cohen: Yes, I still run the program committee and emcee parts of it.

p2pnet: If you could get the people who run BearShare, Blubster, eDonkey, LimeWire, Morpheus and Warez (in alphabetical order ; ) around a table, what would you say to them with respect to their ongoing troubles with the major labels and movies studios?

Cohen: Uh, stop running warez networks?

p2pnet: And if you could do the same with the Big Four record labels, Warner Music, EMI, Vivendi Universal and Sony BMG, and the Big Six studios, Time Warner, Viacom, Fox, Sony, NBC Universal and Disney, what would you say to them with respect to their apparent impasse with the p2p application developers?

Cohen: We’re already talking to all of those entities, and they’re being quite reasonable.

p2pnet: Do you think the current corporate wholesale pricing structure of, so I’m told, 60 to 85 cents for each digital file is reasonable?

Cohen: There are a lot of things which can be a ‘digital file’. We’re going to see considerable evolution of pricing models over time.

p2pnet: As a father, what do you think of the RIAA’s practice of naming children in p2p file sharing subpoenas?

Cohen: I’m not sure what you’re referring to, and of course am not involved in suing anybody.

p2pnet: Do you think people who share copyrighted files are criminals and thieves, as the RIAA and MPAA say they are?

Cohen: It certainly is illegal.

p2pnet: You’ve been very quiet about your brother’s departure from your company? Are you able to say what happened to make him leave?

Cohen: No.

p2pnet: Ashwin Navin is BitTorrent president. How, where and when, did you meet him?

Cohen: We had a friend in common, and met in 2004.

p2pnet: Whose idea was it for BitTorrent to move into the corporate world?

Cohen: I’d wanted to set up a commercial venture for a while.

p2pnet: Before you actually became involved with the entertainment industry, were you ever seriously threatened with court action?

Cohen: Nope.

p2pnet: Did you start the dialogue with the MPAA?

Cohen: They called me first.

p2pnet: If you were approached by the association rather than the other way around, who initially contacted you?

Cohen: Dean Garfield.

p2pnet: How much time have you actually spent with Dan Glickman?

Cohen: I’ve met him in person several times.

p2pnet: Do you and he still talk to each other?

Cohen: I don’t personally talk to him regularly, but people from BitTorrent talk to people from the MPAA on a routine basis.

p2pnet: What kind of discussions are you currently having with the RIAA?

Cohen: Take down processes and future online sales.

p2pnet: Do you believe a time will eventually come when a genuine accord will be reached between the major movie and music companies and their customers?

Cohen: Not sure what you mean. They’re quite happy with their paying customers.

p2pnet: What would you say to someone who’s contemplating launching a music/movie download site?

Cohen: Get licenses.

p2pnet: What would you say will be the three most significant developments for p2p between now and 2010?

Cohen: It’s hard to say what will happen in networking generally, but clearly everything will be dominated by bandwidth price plummeting and throughput going through the roof.

p2pnet: Do you have any new, personal projects in mind, and if you do, what are they?

Cohen: I’ve been working on a new generation of Codeville’s merge algorithms lately, and they’re going to be available for several other version control systems.

p2pnet: What does the future hold for BitTorrent?

Cohen: We’ve got our Allegro release of the client with tons of performance enhancements you can’t find anywhere else coming out, and are going to start making video available on the web site.

p2pnet: Finally, I’ve asked a lot of questions, but I’d also really appreciate it if you’d use this to express any thoughts or comment on topics which haven’t been covered here.

Cohen: We’re expanding to be a common meeting ground for all client developers, so there’s a coherent place where discussions of protocol development take place. A bunch of new documentation is going up there soon, and we’re getting other client developers involved.

p2pnet: Cheers! And thanks. And all the best …



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