DJ Beatmatch Encoder

It’s really rewarding when you develop a script that automates a small part of your life.

Recently, I managed to pull one off which automates part of designing DJ sets.

Before jumping into the program itself, I need to explain a couple things about how I make my mixes, and how I DJ. These are important in understanding how my tool works.

-The music I use to DJ are all files saved on my hard-drive.
-I scan the files with a key detection software (Mixed in Key) which helps detect what musical key my music is written in.
-Mixed in Key also detects the ‘Beats Per Minute’ (BPM) of a song, which is a value representing the tempo.
-My DJ’ing often involves matching the BPM of two songs, allowing them to blend seamlessly.
-Most digital DJ software matches the bpm of two songs for you (called ‘sync’), but my hardware setup (Pioneer CDJ-900’s) does not.

I used beatmatch ‘by ear’, but I discovered an easier way. I can use an algorithm to to beatmatch for me. It’s quicker and more precise, but requires me to write down how much faster or slower each track is than the ‘Set’s BPM’.

I usually write this info on the filename for each song. This whole process used to require crunching numbers of a calculator, then renaming every file in the set.

Now, all I have to do is run a single python script.


Let’s say I’m trying to develop a DJ set.

(Usually a set would be anywhere between 20-30 tracks, but to keep things simple, this one’s 2 songs.)

I already ordered the songs, so I know I’m going to play ‘Don’t Wanna Cry’ before ‘Great Fairy Fountain’. That means it’s time to use my tool.

The Beatmatch Encoder first reads the BPM of the set (or part of a set) and a folder which I’ve planned a DJ set in. I do this my altering the variables for the DJ directory, and for the ‘base BPM’. In this case, ‘example set’ is the directory, and ‘160’ is the set’s BPM.

When run, the script loops over the filenames of all the songs in that folder, reads the BPM of them, does some quick math to find the percentage difference between the song and the set’s desired speed. The script then prints this percentage right after the song’s number.

As you can see, I now have these BPM differences in an easy-to-read format.

Since my DJ equipment reads filenames, all I have to do is read the file on my equipment, and I instantly know what speed to put it at to be a perfect match.

Doing this file-editing manually would take ~20 minutes a set. Now it takes 20 seconds.

While I expect this particular tool to be of niche interest to others (you’d have to mirror my workflow for preparing DJ sets to find this tool practical) but hopefully this gave a little insight into how to simplify your life with a little code.

Average Is Not the Middle: Ratings & Their Distributions

Have you ever read a review and seen something akin to:

“This movie/film/album was average. It took no risks and was completely middle of the road, 70/100.”

I have seen this general review & it’s score dozens of times (though usually with more colourful language). It always struck me as odd. A 5/10 or 50% would be the middle-ground between an abysmal 0/10 and a perfect 10/10, yet I’ve noticed people seem to stand around a 7/10 or 70% when rating a piece of media that is ‘so-so’ but also ‘not bad’.

Is 70% really ‘average’, or have I just been imagining things?

I decided to download several different datasets of internet reviews to find out.

Rather than just sticking to a single website or medium, I decided to look at several different sources. That way, I could be sure that the results were just a by-product of a single website’s scoring system, and instead represented a larger trend in review-scores.

Before looking at all of the different reviews normalized and smooshed into one large dataset (which you can see near the bottom) I decided to take a quick look at the datasets individually- just to see if they stood out differently from one another, or if one of them was completely unlike the rest.


Metacritic: Metascore (Videogames)

Metacritic has two different types of scores it uses: Metascores and User scores.

According to the Metacritic Website, their ‘metascore’ is a weighted average of individual critic scores. They take a bunch of reviews from official critics, assign a ‘weight’ to each of the critics, ‘normalize’ all the scores (so a 9/10 becomes a 90/100, a B+ becomes an 83, etc… Then they base their metascore off of this.

Reverse engineering how metacritic gets their metascores scores would be worth an entire article on its own (one that has already been done by someone else, no less). Suffice to say, the ‘meta’ of metacritic is because their review is supposed to be the result of many others.

Metacritic Scores and # of ratings which fall into them

We see an obvious peak around the mid-70’s, but other than that, a fairly normal & tapering off in both directions. Consulting with the Metacritic website again, ‘Mixed or Average Reviews’ for videogames fall between 50-74%.  Based on that, I would have suspected that the peak of the bell-curve would’ve fallen in the middle of the ‘Average Reviews’ score range (62%). Instead, it peaks around the 70-73% range- illustrating that a 70/100 score is, indeed, average. It’s also nice to know that the average metascore is actually within the boundaries of ‘Mixed or Average Reviews’, even if it’s touching the upper-ceiling of that classification.

Metacritic: Userscore (Videogames)

Userscores on Metacritic follow a far simpler process: Metacritic users submit a personal score between 1 and 10, Metacritic averages the submitted scores from all users, and voila, the user score is created.

Here, we’re seeing a peak around the 8/10 range. This would be an ~80% when compared to the ~70% of Metascores, showing a clear disparity between user scores and critic scores.

I suspect this is because of a self-selection bias: a user can pick and choose what he wants to play, while a critic often cannot.

I looked at the relationship between these metacritic Metascores and Userscores in a separate article here.


IMDB Film Ratings:

IMDB’s scoring system is also determined by popular vote among users. IMDB mentions that its rating system is a weighted average designed to “eliminate and reduce attempts at vote stuffing by people more interested in changing the current rating of a movie than giving their true opinion of it.”

Suffice to say, these scores are largely determined by users, though some users (who presumably have proven themselves in some way to be reputable at voting) have more of an impact than others.

Histogram IMDB Review Score


The average IMDB score is definitely lower than the average metacritic score. The middle of the bell-curve here is clocking in around 6.8, and tapers off aggressively below 6.0 and above 7.6.

This is looking ever-so-slightly lower than a ‘70%’ average, but it’s certainly higher than a ‘50%’ one, too.


Pitchfork Music Ratings:

Pitchfork’s rating system is far less ‘by the numbers’ than Metacritic or IMDB. A single writer for Pitchfork will review a specific album, giving it a write-up explaining their thoughts about it, and also giving it a numerical score out of 10. The write-up is ultimately meant to help inform & give rationale for the 0-10 rating- providing accountability for specific scores.

If Pitchfork has a “formula” for their reviews, they don’t have it explicitly posted. Though given their entire team of reviewers can be viewed on a single page, I would imagine their reviews are more of a practiced art than a science.

Pitchfork Histogram

Of all the individual datasets, this one is easily the most interesting. Pitchfork has reviews out of 10, but they also give decimal values (rather than just giving an 8/10, they may give a 8.2/10.0). In essence, this means their reviews function similarly to a review out of 100. However, if you look at the above graph, you may notice that, relative to nearby bars, the tallest peaks are on whole numbers. It seems critics are still more apt to assign a ‘6.0’ than they are a 6.1 or 5.9. If you ignore the numbers at the bottom for a moment, you can probably make an educated guess as to where 7.0 would be in relation to the peaks for 6.0 and 8.0.

Another trend worth noting is the sheer number of 8.0 reviews. The Median (which, in many ways, signifies the “middle” of our hill of ratings) of this dataset is 7.2, yet 8.0 is where a majority of reviews sit.

The likely explanation for this phenomenon has to do with Pitchfork’s review categories. The site has a special category for ‘8.0+ reviews’, which only gives you search results which scored 8 or above. I suspect there is a similar thought process for many reviewers: “I’d give this a 7.8 or 7.9, but I think it deserves to be seen on the high-score list”. Perhaps you also end up with reviewers who feel something is “the worst of the best”, and that it deserves to be on the high score list, but only at the very lower threshold of it.

Whatever the reason may be, we see many ratings of around 80%, and a large pool of reviews around the 70% range, too. Once again, it looks as if 5.0/10 or 50% is far from the average score.

All together:

So far we’ve seen some pretty compelling evidence that the average review for something lies higher than 50/100. But from the looks of it, there’s still a bit of variation from review-system to review-system as to what exactly IS a “middle-score”.

Setting out to find the answer to this, the following is a combination of all four datasets together. Since Metacritic User Scores & Pitchfork reviews were only out of 10, they were multiplied by 10, normalizing them to a 100 point scale.

Also, since we’re looking for the average review (across different websites and creative mediums), I chose not to ‘weigh’ any of the datasets differently. This means the the smallest dataset (IMDB film ratings) will play a far smaller role in the end result than the largest dataset (Pitchfork Music Ratings). However, since we’re trying to find ‘the average review’ independently from whatever rating system or site it is from, we are going by the sheer number of reviews, it makes sense to treat every review with equal importance.

Histogram of Reviews from Metacritic, IMDB, and Pitchfork

You may notice that, unlike the previous bar-graphs, this one doesn’t measure the # of entries for each bar, but instead looks at what proportion of reviews that fall into each bar. Rather than simply showing ‘how many’ reviews gave a specific score, this helps to inform us about what percentage of reviews fell into each bar. We see how the tallest peak (80/100) touches the 0.040 tick, therefore account for about 4% of the overall reviews.

The results here appear to cluster strongly around the mid-70’s range. Both the mean (69.98) and median(72.0) are fairly close to a score of 70/100.

While looking at things from a purely scientific point of view, there are a number of factors to consider which prevent me from generalizing these results to talk about EVERYONE. Mainly, all of these reviews are collected from the internet and are operated/designed with an English-Speaking audience in mind.

That being said, the implications of these results are fairly clear: A 70/100 review can often be interpreted as ‘average’.

As to why this is the case: I have my theories, but I will leave them for another day.


Metacritic Reviews: Metascore vs. Userscore

For an upcoming project, I had to determine whether or not Metacritic’s ‘Meta-score’ (aka the ‘critic score’) and ‘User score’ were different enough that it was worth analyzing both datasets. The data is for video game reviews, and each point presents the final score given for a game.

It turns out, they are similar, but less than you might think.

Metacritic Metascore vs. Userscore
Statisticians and Data-nerds can note that the correlation had a strength of 0.536, and a p-value of <0.05


Meta-critic Metascore & User Scores have a moderate positive correlation to one another. These results are statistically significant.

To simplify that statement: The relationship between Metascores and Userscores generally line up with one another. Most of the time, critic and user scores are pretty close to one other. When one group gives a high score to a game, generally so does the other. Likewise with low scores, or scores that fall somewhere in the middle.

Because this is only ‘moderately’ correlated, there are still a lot of times when the two scores differ. The little dots that are further away from the main “swarm” are ones where one scores is vastly different than the others.

With the number of datapoints and their placement, the chances this result happened due to “dumb luck” is exceptionally low.

You may notice that Critic scores are out of 100, while User scores are only out of 10. Aside from giving a little less ‘wiggle room’ for users, this doesn’t effect the analysis too heavily. Users can only rate something out of 10, but the overall rating on a videogame can still have a decimal point in it (i.e. 8.7/10)


Even beyond looking at a specific genre, most users develop a ‘taste’ for certain games, based on franchises and game studios. Gamers learn what games they enjoy, and what games to avoid. Critics often lack that freedom, and may be circumstantially forced to play games they may have a negative predisposition towards, or would otherwise not consider better than “middle of the road”.

Critics may have to “take one for the team” and review the occasional game they know is going to be awful. Users just know to avoid them.

Another possible explanation is simply that critics score lower because they are…critics. Their goal is to accurately assess the quality of a game as best as possible.

Theories aside, the results of this correlation told me what I needed to know. ‘Metascores’ and ‘Userscores’ are different enough that I can include both in my next analysis.

Game Sales: a Visual Analysis

This’ll be the first in a series of articles/visualizations on ‘Data Trends’

Let’s start with something simple – stats about Video-game sales. This data was compiled by, a website that focuses on sales trends within the gaming industry.

Much like how Hollywood movies have an ‘upward trend’ in the #1 box office sales each year, I expected the same to be true for videogames. I anticipated an upward trend in the # of sales of newer games, with the top-selling games constantly breaking sales records each year.

“Best-seller” of the year:

The following shows the sales of the ‘best-selling’ videogame of each year.

Game Sales by Year

This defied my initial expectations. We see peaks and valleys between the yearly best-sellers. The highest record was around 40 million being set in 1985, and then the next highest was in 2006.

Let’s take a second to talk about the top 7 selling videogames of all time:

# 1: Wii-Sports (2006)

#2: Super Mario Bros. (1985)

#3: Mario Karts Wii (2008)

#4: Wii Sports Resort (2009)

#5: Pokemon (1996)

#6: Tetris (1989)

#7: New Super Mario Bros. (2006)

So what’s similar between all of these games? Aside from being produced by Nintendo (who also hold the record for 22 of the top 25 best-sellers of all time).

I did some googling on these titles, and all 7 games all had ‘bundle’ deals, where you could purchase them as part of a bundle with your game console- essentially giving you a free videogame with a purchase of the device to play videogames on.

Successful games would already be strong consideration to be bundled with the consoles, but these package deals may have contributed to making these games all-time best-sellers.

Even with the data in front of us, it’s hard to imagine Wii Sports selling 82.83 million copies…That’s more than twice the population of Canada (36.29 million in 2016).


Average sales per year:

Shocked that best-selling game records aren’t constantly being beaten, I looked to other statistics. If the best-selling video-game isn’t breaking records each year, I considered that perhaps the average game was selling more copies.

Once again, I am completely wrong.

Mean Videogame Sales by year

We clearly see a ‘golden age’ of game sales, starting in the mid-80’s and ending in the early 90’s. Things seem to flatten out after that, but sales are nowhere near the monster they are before.


(Bear in mind this is only the top ~16600 games sold- with the bottom of the list only getting around 10k sales globally. Even if the effects on overall averages are only slight, I’m sure there’s a chance that the “bottom of the barrel” sellers who never even made the list have a chance of skewing averages lower. )

This prompts even more questions. I anecdotally hear about how the game industry is growing, and yet these numbers don’t reflect that.


Number of games made:

Games Made Per Year

Finally, something that rises, rather than falls!

While numbers seem to be on the decline from the mid-2000’s forward, the number of games being produced are still far higher than they were in the ‘early days’. It’s quite possible that the number of games on the market now is part of the reason why the average game sold fewer copies.

So, more games are being made, but are people buying them?

From the looks of it, yes. The total amount of games SOLD per year is also increasing:


Total Game Sales:

Ancedotes about the gaming industry growing are not unfounded. It’s just that rather than a couple of games dominating in sales, there’s a more diverse marketplace from which to choose from.

The ‘average’ game may be making less revenue past the mid-90’s, but with more options for games available, it’s not due to dwindling interest. There’s simply more competition, and more diversity in what gamers can buy.

As they say, variety is the spice of life. When more games are available, more games are being bought.

Film Box Office Sales vs. Game Sales – Upward Trend

I made a comment earlier in this document about how film sales are on an ‘upward trend’. To validate my claim, the following is a trendline of the best-selling film of the year. Just to give some context, you can also see the best selling Videogame of the year below it.

Box Office Sales vs. Game Sales

Sources: Box office grosses:

It’s interesting the consider how best-selling movies are on an incline, while the best seller for videogames are, by comparison, fairly steady. I would hypothesize that this would have to do with the consolidation of film studios, leading to fewer studios competing, and more resources being pooled into marketing for the biggest films of the year, though that would be worth another analysis altogether.


Outliers , oddities, and points of note:

The data used in this analysis was scraped during 2017, likely during the beginning of the year. I choose to remove 2017 data because 2017 isn’t over yet, and many of the games that have come out this year are missing.

Games that were sold cross-platform were evaluated by their sales for each individual platform. So, say, Grand Theft Auto V would be evaluated by its PS4 sales, it’s XBOX sales and it’s PC sales separately.

It’s also important to note that these dates mark the year the game debuted. It may not necessarily be the year the game made the most sales. As a result, it’s important to consider that the production run of a single videogame is going to play a major factor in its global scales.

As a result, I would argue the data is ‘incomplete’ on any game that still hasn’t finished its production run. They still have potential to climb significantly in sales. Especially for games from 2016, which I suspect are still on the shelves.


I hope you enjoyed this analysis. If you’re interested in similar articles, be sure to check the Research & Data section of my site!