Comment Feed for Countdown to PDC2008: Secrets Revealed (Charles on Channel 9)

Re: Re: Re: Re: Countdown to PDC2008: Secrets Revealed

Sergey Smirnov — Mon, 08 Sep 2008 17:57:00 GMT

Thank you, Fridjon. That’s very generous of you. I mean both your comment and the right arm offer :) My plan now is to see what Mike comes up with this week. If I’m lucky, I might earn a left arm from someone else’s t-shirt. Eventually, I hope to end up with a unique stitched thing with some history behind it. It’d be nice if the pieces were in different colours and signed by the owners :) :) :)

Re: Re: Re: Countdown to PDC2008: Secrets Revealed

Fridjon Gudjohnsen — Mon, 08 Sep 2008 15:07:51 GMT

Actually Sokol, your comment with the recording as you heard it was of great help to me. It confirmed that there was another recording and the seed you listed (the 5th perfect number) also confirmed for me that "perfect numbers" were used. Thanks.

If I get an XL sized T-Shirt I could probably spare you the right arm :)

Re: Re: Countdown to PDC2008: Secrets Revealed

Sergey Smirnov — Mon, 08 Sep 2008 06:58:24 GMT

Thank you for the audios, Mike. I think I made a mistake decoding the first file. In my version, each sample in the source audio was used to populate the resulting audio only once, so that my version of the output audio contaned samples with unique indexes. This overkill apparently resulted in a bit more distorted audio which prevented me from picking the name, Carol, correclty. Anyway, it was quite an enjoyable challenge. How about half-a-tshirt, perhaps, a vest? :):):)

Re: Countdown to PDC2008: Secrets Revealed

mswanson — Sun, 07 Sep 2008 04:22:51 GMT

For those who'd like to hear the two decoded files:

The first file decoded using the 5th perfect number (33550336)
The second file decoded using the 10th Carol number (1046527)

Re: Countdown to PDC2008: Secrets Revealed

Sergey Smirnov — Sat, 06 Sep 2008 08:31:52 GMT

Congratulations Fridjon! I knew that the name on the audio had something to do either with filtering out the noise or with further encoding. But my comrehension skills are limited:) I obviously tried GAIOL as another seed or a filter, but it didn't help.

Re: Re: Countdown to PDC2008: Secrets Revealed

mswanson — Sat, 06 Sep 2008 06:31:56 GMT

Awesome solve, Fridjon! Thanks for sharing your steps. The last audio file is less distorted, because it was mixed-in last during the encoding process. As such, its samples basically "won." The only reason there's any distortion is because the random number generator picked some of the same encoding locations more than once.

Honestly, I thought that this puzzle would take a little bit longer to solve. :-)

Re: Countdown to PDC2008: Secrets Revealed

Fridjon Gudjohnsen — Sat, 06 Sep 2008 01:32:04 GMT

IF YOU WANT TO SOLVE THE PUZZLE ON YOUR OWN THEN PLEASE COVER YOUR MONITOR NOW!

The message in the audio file talks about "nothing left to chance", "seed", "ordering samples from the entire collection" and the importance of "the correct seed" being a "perfect number".

The .wav audio file is (like all other such files) made up of a header followed by samples, the actual values of the audio. When combining this together a solution comes to mind of picking samples randomly from the whole list of samples, but starting with some seed of a "perfect number". A further hint for this solution was a remark Mike made, that his friend in the .NET Framework team was behind all this, this could mean that the Random class of the .NET framework could be used for generating the random numbers. I wrote some C# code to do actually that:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace PDCPuzzle
{

class Program
    {
        private const int SEED = SOME_PERFECT_NUMBER;

        static void Main(string[] args)
        {
            // Read the whole input file in memory
            byte[] audio = File.ReadAllBytes("audio.wav");
            // Create a new buffer for the output file
            byte [] output = new byte [audio.Length];
            // Copy the WAV header from the input file to the output buffer
            for(int n=0;n<44;n++)
                output[n] = audio[n];
            // Seed the random number generator with the correct seed
            Random rand = new Random(SEED);
            // Iterate through all samples
            for (int n = 44; n < audio.Length; n+=2)
            {
                // Select a random sample (each sample is 2 bytes long)
                int hit = rand.Next((audio.Length - 44)/2);
                // Copy the sample to the next sample slot in the output file
                output[n] = audio[44+2*hit];
                output[n+1] = audio[45 + 2 * hit];
            }
            // Write the output file
            File.WriteAllBytes("audioout.wav", output);
        }
  }
}

Now we only need to pick the value of the seed, preferably a perfect number.

As tfraser pointed out in the comments, there is a mathematical concept of a perfect number.
There are only 5 such numbers that can be represented by Int32 (which is the type of the seed parameter to the Random class constructor). When we use the 5th perfect number (33550336) as a seed we get a new audio message. This message says:

"Hello, you have reached Carol's number, thats C A R O L. I am currently unavailable please try again using one of my other numbers"

Well since the perfect number was a mathematically defined number, is there perhaps something called a Carol Number? Yes indeed there is, and one of them, 1046527, yields a (somewhat better quality) audio file that asks the question: "What's the name of our PDC 2008 marketing manager?"

Re: Re: Countdown to PDC2008: Secrets Revealed

mswanson — Sat, 06 Sep 2008 01:04:22 GMT

Impressive, Fridjon! Indeed, the correct answer is "Denise Begley." Great job! I love that you guys are able to figure these out. As long as you're having fun solving them, I'm happy to continue inventing them. :-)

It's certainly up to you whether or not you'd like to explain how you solved it, but I, for one, would love to hear the thought process you went through to come up with the solution.

Drop us an e-mail at pdccount (at) microsoft.com, and we'll coordinate your extremely limited edition PDC2008 internal t-shirt.

Re: Countdown to PDC2008: Secrets Revealed

Fridjon Gudjohnsen — Sat, 06 Sep 2008 00:26:46 GMT

BTW Sokol, I think the name was CAROL on that recording :)

Re: Countdown to PDC2008: Secrets Revealed

Fridjon Gudjohnsen — Sat, 06 Sep 2008 00:25:21 GMT

I believe Denise Begley is doing an excellent job as the Marketing Manager for this PDC.

Re: Countdown to PDC2008: Secrets Revealed

Sergey Smirnov — Fri, 05 Sep 2008 21:30:52 GMT

Yet another small correction (if it matters): 'Hello, you've reached GAIOL's number. THAT'S G-A-I-O-L. I'm currently unavailable. Please try again using one of my other numbers." Sorry for multiple posts:)

Re: Countdown to PDC2008: Secrets Revealed

Sergey Smirnov — Fri, 05 Sep 2008 20:49:02 GMT

OK, I'm really confused about the the name, but it's spelt like GAIOL. So the corrected text is 'Hello, you've reached GAIOL's number. G-A-I-O-L. I'm currently unavailable. Please try again using one of my other numbers."

Re: Countdown to PDC2008: Secrets Revealed

Sergey Smirnov — Fri, 05 Sep 2008 20:31:51 GMT

Sorry, English is not my first language, so I might have missed something on the audio.
It goes like: "Hello, you've reached Gail's number, GAIL. I'm currently unavaliable. Please try again on one of other numbers".
Seed:

33550336

Re: Re: Countdown to PDC2008: Secrets Revealed

mswanson — Fri, 05 Sep 2008 19:23:50 GMT

Thanks, Winslow. I probably should have learned this during the Olympics, but it somehow slipped by me.

Re: Countdown to PDC2008: Secrets Revealed

Winslow — Fri, 05 Sep 2008 19:09:34 GMT

Beijing is pronounced "Bay-Jing" not "Bay-zhing"

Re: Re: Countdown to PDC2008: Secrets Revealed

mswanson — Fri, 05 Sep 2008 17:13:49 GMT

cairn: Even better, just like MIX06, MIX07, and MIX08, we'll publish the session recordings within 24 hours of the actual session on the internet (with resources, like the PowerPoint decks). For anyone, for free...regardless of whether or not you were an attendee. For network access, the Los Angeles Convention Center has upgraded its "pipe" since 2005, and because the net plays a much more important role, we put a lot of effort into providing great access this year. I suspect you'll be very pleasantly surprised.

Re: Countdown to PDC2008: Secrets Revealed

cairn — Fri, 05 Sep 2008 16:43:56 GMT

After the PDC, will we get all the session video's and powerpoints on disc?
and will we get te same type of network access as per PDC05.

Re: Re: Re: Re: Countdown to PDC2008: Secrets Revealed

Charles — Fri, 05 Sep 2008 16:11:31 GMT

Thank you for doing this Mike nd Ritzy. These are great and fun to watch. Mike, your challenges are awesome, as expected.

Keep on posting,
C

Re: Re: Re: Countdown to PDC2008: Secrets Revealed

mswanson — Fri, 05 Sep 2008 15:16:06 GMT

All I'll say is that it's great to see you guys sharing ideas on the forum, and I love the thinking that's going on. :-)

Re: Re: Countdown to PDC2008: Secrets Revealed

Samuel Jack — Fri, 05 Sep 2008 12:43:01 GMT

Could that be the reason why the sound file sounds distorted (assuming that it does for everybody else)?

Re: Countdown to PDC2008: Secrets Revealed

Philip Fitzsimons — Fri, 05 Sep 2008 11:18:52 GMT

"when ordering samples from out entire collection, be sure to start with the correct seed"

hmm, interesting

"sample" and wave files... and "order" with "entire collection"
implies data might be held at perfect number offsets in the data chunk?

Re: Countdown to PDC2008: Secrets Revealed

Samuel Jack — Fri, 05 Sep 2008 09:29:58 GMT

Is it appropriate to post our thoughts about the hard hat challenge here?

"Nothing being left to chance" and "seeds" makes me think of deterministic "random" number generators. And I presume we're talking the mathematical definition of "perfect" here: a number which is the sum of all its divisors apart from 1.

Re: Re: Countdown to PDC2008: Secrets Revealed

tfraser — Fri, 05 Sep 2008 07:40:21 GMT

This is a very interesting problem. Without giving anything away, would you be able to clarify whether or not the mention of 'perfect number' in the audio file is referring specifically to the mathematical context of the term?

Re: Re: Re: Countdown to PDC2008: Secrets Revealed

mswanson — Fri, 05 Sep 2008 06:12:02 GMT

Sorry, Chadk, your answer--while nice and geeky--is incorrect. Like the other Hard Hat Challenge answers, this isn't something that you could easily guess.

Re: Re: Countdown to PDC2008: Secrets Revealed

Chadk — Fri, 05 Sep 2008 04:01:14 GMT

The answer is 42.