How can I find out the time signatures of a diverse group of songs?
April 30, 2014 7:23 AM   Subscribe

In preparation of my MeFi Swap playlist, I'd like to cull through the massive list of possible songs I've generated by sorting them by tempo. I'd like to do this without manually listening to songs to compare them to one another (partially because I don't think I'd be particularly good at it). Is there any resource online for finding out the tempo of songs, either a database with that kind of information or an app which I can feed an mp3 to find out?
posted by ocherdraco to Media & Arts (14 answers total) 2 users marked this as a favorite
Do you know what the difference between tempo and time signature is? It's not clear what you are asking.
posted by thelonius at 7:31 AM on April 30, 2014

Looks like might be what you're looking for - not time signature, but beats per minute, which seems like it might actually be what you're looking for more than time signature (which would be whether it's in 5/4 or 2/2 or something like that).

However, for me, bpm doesn't necessarily correlate with the perceived tempo... a song with a driving beat can feel much faster than a technically faster but more easygoing song.
posted by mskyle at 7:31 AM on April 30, 2014 [1 favorite]

Response by poster: thelonius: "Do you know what the difference between tempo and time signature is?"

Ha, apparently I don't. I thought those were the same thing. Complete lack of formal music education, here. (If you don't mind, could you explain the difference? And does bpm correlate with one or the other, or is it something else entirely?)

Beats per minute seems to be what I'm after.

It's okay if bpm doesn't align with tempo exactly—this is primarily to get a rough grouping, not exact matches.
posted by ocherdraco at 7:35 AM on April 30, 2014

Time signature is (more or less) the notation that shows how many beats are in one measure (or "bar") of a piece of music. It's written as a fraction, like 4/4. Most pop and rock and R&B music is in 4/4: a quarter note (the "4" in the denominator) is one beat, and there are 4 of them per measure. Think of a typical big rock drum beat: one TWO three-and FOUR. 3/4 is the time signature that a waltz is in: one TWO THREE, one TWO THREE. There are plenty more, which are usually seen as exotic in European music, but there are cultures where the normal folk or dancing music uses stuff like 5/8. Examples: the Pink Floyd song "Money" is mostly in 7/4, Dave Brubeck's "Take Five" is in 5/4.

It seems to me that it would be a lot easier to determine beats per minute automatically than it would be to determine a time signature automatically, so maybe someone has done what you are looking for, especially since DJs care about this a lot I think.

I hope that helps and I am sorry if I sounded snooty.
posted by thelonius at 7:59 AM on April 30, 2014

Time signature is a lot harder to get hold of than tempo. Here is a link explaining how to get it programatically from EchoNest via their API. But not all the songs in their database have the time signature recorded (by any means) - and you can only make so many calls. The basic problem you will have with key signature is that it is not widely recorded.

The terms "tempo" and "beats per minute" are often used interchangeably - they are not really the same however - and the tempo is really a determination of how you choose to group the beats.

In terms of getting BPM for your songs there are many options since it is used by DJs. Itunes includes a Beats Per Minutes column to store this information. As a windows user I find that programs like Beatunes and Jaikoz are good and going through my large collection of music and getting information such as this. Neither option is free if you want all the features but both will let you get a feel of whether you like them before charging you for the full version. Many of these applications use central databases of song information such as the one at MusicBrainz. They produce an application called Picard that you might want to try.
posted by rongorongo at 8:00 AM on April 30, 2014 [2 favorites]

Response by poster: thelonius: "I hope that helps and I am sorry if I sounded snooty."

Not snooty at all! And thank you, that explanation is very informative.

rongorongo, those look like excellent resources for what I'm after. Thank you.
posted by ocherdraco at 8:02 AM on April 30, 2014

rongorongo, what you link to isn't explaining quite the same thing that you are. "Beat" and tempo aren't the same thing, but beats per minute and tempo are pretty much equivalent. The tempo being a determination of how you choose to group the beats is inaccurate- that's what time signature is. The tempo marking on a piece of music is literally a note symbol (half or quarter or whatever) an equals sign and a number. That number indicates the number of beats per minute. Just like thelonius, don't want to be snooty- just to make sure that things are clear to ocherdraco!
posted by Polyhymnia at 12:05 PM on April 30, 2014 [2 favorites]

To be insufferably pedantic, the time signature is not a fraction. It just looks like a fraction because of the typographic convention used to display it.
posted by under_petticoat_rule at 12:24 PM on April 30, 2014 [2 favorites]

"It's written as a fraction, like 4/4"
posted by thelonius at 12:25 PM on April 30, 2014

I've used the MixMeister software (Mac version) with good results. Costs a few dollars. It can directly populate the BPM field if your files are mp3s.
posted by doctord at 3:51 PM on April 30, 2014

"It's written as a fraction, like 4/4"

Yes, you've correctly identified one of the statements you made that are likely to perpetuate the misconception that time signature is a fraction.
posted by under_petticoat_rule at 4:52 PM on April 30, 2014

Response by poster: Thanks for all the explanations, everyone!
posted by ocherdraco at 6:14 PM on April 30, 2014

"it's written as" is different from "the typographic convention used to display it" how?
posted by thelonius at 10:20 PM on April 30, 2014

Polyhymnia: Thanks for the clarification.

ocherdraco: I think an implicit part of your question is "How to I make a mix of songs which sound musically really good together?". As mskyle suggests, simply identifying two songs with the same BPM and then mixing them together does not always produce an appealing result. This could be to do with differences in key signature, loudness and so on - but the most important ingredient that we have not mentioned so far is differences in the musical keys of the two pieces at the point where they come together. If the first song is in C and the second is also in C then that the mix should sound OK (although the sequence will start to sound monotonous if you have too many songs in the same key). If the first song is in C and the second in in C# then that will probably sound discordant. And if the first song is in C and the second in G major (for example) then the mix will have an uplifting effect - a good trick if you want to delight your listeners in any musical genre. To DJs the rules being followed here are known as Harmonic Mixing - musicians - whether they are composing a song or assembling a set - may know these relationships as The Circle of 5ths.

I mention all this because the sort of tools and song databases I mention above will also be able to tell you the key of each track in your music collection. With this data you could experiment by mixing (or just sequencing) songs which are not just of a similar tempo but which are harmonically compatible.

Incidentally - I notice that, for my library at least, Itunes "Genius" mixes tend to follow harmonic mixing guidelines for the keys of successive tracks. Apple still don't seem to be happy about saying how Genius works but my guess is that they are using song key as part of their secret sauce.
posted by rongorongo at 3:26 AM on May 1, 2014 [2 favorites]

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