Kebe Says - Dan McDonald's Blog

That I had to explain MTV's acronym... eeesh.

When Cable TV Was Still Young

Set the wayback machine 40 years plus 6-8 months ago (from the date of this post). Cable TV was rolling out in my suburb of Milwaukee, and it FINALLY arrived at our house. Hurray! We didn't have HBO, but we DID have all of the other fledgling basic cable channels... including Nickelodeon, which was then one of the Warner Amex Satellite Entertainment Company (WASEC) channels. (WASEC, and its progenitor Columbus, Ohio QUBE project, are its own fascinating story.) Nickelodeon mostly had single-digit-aged kids programming, but at night (especially Sunday night) it had a 30-minute show called PopClips, which would play the then mindblowing concept of music videos... or as one friend of mine called them, "Intermissions" (because HBO would play music videos between movies to synch up start times... I didn't have HBO so I trusted him). There is a YouTube narrative video that discusses the show in depth, including its tenuous link to another WASEC channel that was going to start airing 40 years ago today...

I Want My MTV

Anyone sufficiently old knows that MTV stood for Music Television. At midnight US/Eastern time on August 1, 1981, it played its space-program-themed bumper, followed by, "Video Killed the Radio Star" by The Buggles.

Now the local cable company pulled a bit of a dick move with MTV for us. It attached it to HBO. If you didn't have HBO, the cable company scrambled MTV, albeit not as strongly as they did with HBO. They scrambled it by making the picture black-and-white, and cutting out the sound completely. LUCKILY for me, we did have "cable radio" which let us not only get better FM reception, but also the stereo broadcast for MTV. Combine them, and I got to see black-and-white videos with proper sound.

Thanks to people's old videotapes and YouTube, you can watch (modulo a couple of copyright-whiners) the first two hours of MTV here. I'd have embedded this, but I'm guessing the copyright-whiners won that battle too.

There's a lot to unpack about MTV being 40. I'm not going to try too hard in this post, but there are some things that must be acknowledged:

• MTV was a generation-defining phenomenon for Generation X. I suppose late-wave Boomers (the last of whom were graduating high school or already in college) could make a claim to ownership of MTV's first audience, but as MTV matured, it was very much initially for us Xers.
• It was initially narrowly focussed. The only Black people you'd see on MTV initially were JJ Jackson or members of The Specials. That changed a couple of years later, however.
• It spawned at least one knock-off: Friday Night Videos, which unlike MTV didn't require Cable.

Of course MTV doesn't play music videos on it anymore, we have alternatives now: YouTube, DailyMotion, and their ilk. And if you miss your MTV, or want to know what it looked like, you really don't have to look hard; many people have uploaded at least some VHS rips, many alas without music thanks to copyright teardowns. But with artist often putting out their old music on their own YouTube pages, some have taken to curating lists of them. Even NPR has curated the first 100 songs!

My birthday is upon me.

My birthday present was an iPhone 4. Yeah, I got it early, but it was nice to have for my just-finished vacation drive. I noticed that when I'd reshuffle the 1763 songs on there, I'd more often than not hit a collision with a song I swear I'd heard during the previous shuffling. Time for some math...

The Birthday Problem (or Birthday Paradox, not because it's a real paradox, but because it's counterintuitive) shows that it only takes 23 people to be in the same room before the chances that two of them share a birthday are equivalent to a coin flip. The link above shows how one derives this. Basically, as you keep adding people, the probability of there NOT being a shared birthday decreases. That probability hits near-enough to 50% at 23 people.

I figured if I would have listened/remembered 30 songs from a previous shuffle. That's 2-3 hours of music, not a lot when you're driving all day. So if I accidentally shook my iPhone and reshuffled the songs, how many would I need to hear until I had a coinflip's chance of hearing a repeat from the previous 30?

Basically, the probability of NOT hearing a previously-heard song was (1763-30) / 1763. If that wasn't a repeat, the probability of another non-collision would be (1762 - 30) / 1762. Note that unlike the birthday problem, I'm decrementing the denominator as well. This is because I'm not going to hear the same song twice in a random shuffle.

I wrote a C program (because I hack way too much ON code) to compute things. Here it is:

#include <stdio.h>

int
main(int argc, char *argv[])
{
        double p;
        int i, listened, total, tries;

        if (argc != 4) {
                fprintf(stderr,
                    "usage:  ipod [listened-songs] [total-songs] [tries]\n");
                return (1);
        }

        p = 1.0;
        listened = atoi(argv[1]);
        total = atoi(argv[2]);
        tries = atoi(argv[3]);

        for (i = 0; i < tries; i++)
                p *= (double)(total - listened - i) / (double)(total - i);

        printf("P(NO repeat for %d on the second playthough): %lf%%\n", tries,
            p * 100.0);
        printf("P(Repeat for %d on the second playthough): %lf%%\n", tries,
            (1 - p) * 100.0);
        return (0);
}

Turns out, I need to hear 40 songs to have a coinflip's chance of hearing one of the previous 30 songs I heard before reshuffling the 1763 total songs.

mactavish(~/sources)[0]% ./a.out 30 1763 40
P(NO repeat for 40 on the second playthough): 49.942794%
P(Repeat for 40 on the second playthough): 50.057206%
mactavish(~/sources)[0]% 

The above program should work for any sized iPod/iPhone collection, or any sized song-memory/patience. I really hope I got the math/derivation right. Any probability wizards in the audience can feel free to school me in the comments section.