The core principle of the Spectrum Editor--What is the rhythm of music

Objective
The previous blog post, "I used cocos2d-x to simulate the Live scene of 〈love live! College Idol Festival", mentions a spectrum maker, and some readers say they want to talk about how this thing is done. The editor is not a confidential material, originally thought of the production process from start to finish, but finally found that too much lazy cancer late abandonment of treatment .

The project in that blog post is the demo of Easy live!. "Easy live!" is my design of a running on WP, can choose to play the spectrum and there is no LP limit of the simplified version of the "Love live! College Idol festival", simply said to be a ll of the practice, although it has not been finished and then I jumped the u3d pit and then did not then (Dead

El was started after the development of the editor was completed. Write the editor when do a bit random, the inside of the code is not organized, more chaotic, not open source fog island everyone thinking.

So this article is mainly about the core of the editor, the principle of the logic is also applicable to other rhythm class game.

Note that this blog post does not cover the Code section .

Target

The function of the editor is to create new or open profiles, add and delete objects, set the time they appear for objects, and then export them to the format needed by the game. And the time the object is set up is the core function of the editor.

Take the editor I made for example. The time of the object depends on which line it is placed on (in fact, as far as I know, the editor of most other rhythm games is basically putting things on the line, or the time at which the lines correspond), our goal is to ask for the time of the dash.

　　

How can I ask? Keep looking, and then introduce some professional vocabulary.

"BPM and sub-pat"
We know, throwing classes, practicing, the plot, the core part of LL is a music game. If the game is played, the hand is steady, you will feel that each object sounded time and song particularly close to the beat, this feeling in easy and normal difficulty more obvious. If we artificially play fast or slow down, that is to say that the object sounded a little bit faster or slower, listening is particularly awkward.

Then there is a problem: the time to make the object sound in tune with the song itself. In other words, the time of the horizontal line should be related to the song itself.

And what about the song? Don't worry. Let's listen to a small piece of music. Note that when the music starts playing, try to clap your music:

Baidu Network Disk ("The city of the で りたい" at the beginning of the clip)

If your musical sense is not too bad, you will find that the frequency of your high-fives is certain. If you find yourself looking for a random, try it several times.

If it still doesn't matter, then listen to the version that added the tick:

Baidu Network Disk

If the music is not too bad, the frequency of your clapping and the ticking sound should be the same.

In musicology, the tick frequency is defined as the number of Beats per minute of the rhythm. It represents the number of ticks per minute at this rhythm. This value is usually written as BPM (Beat Per Minute).

The interval between two adjacent ticks is called a time of the beat.

What if we binary the time of a beat? Obviously, the frequency of ticks will increase by one more times. At this point the gap time for the two adjacent ticks is 1/2 of the time of a beat, called the two-point shot.

And so on, there are three beats (usually for the music that BPM can be divisible by three), four beats, six beats (usually for music that BPM can be divisible by six), eight beats, and so on.

To be sure, as long as the sound of the object is sounded at the moment of the split, it sounds as if the person will feel harmonious.

In fact, the arranger in the composition of the time, the notes are also placed on the sub-film, the spectrum of the author in the creation of the time, the object is also placed on the sub-pat.

So now you can answer the previous question: The time that makes the object sound, and the BPM of the song .

Why do people feel harmonious when they hear the sound of a split shot? I'm sorry, I can't answer that, maybe it's about the structure of the brain? Interested readers can check the information themselves.

"Bars and beats per bar"
First, what is a subsection. The encyclopedia explains that "the music is in progress, and the beat and the weak are always circulating regularly, from a strong shot to the next one, which is called a section."

It's still a little confusing to see the text. Let's play the audio with the tick again.

　　It can be heard that the ticking of the voice is a "tick answer" for a group, repeated repeated. The time elapsed for each "tick answer" is a subsection.

If you listen to the release of the Tick, you can feel the sound of the music itself in the "drop" sound and "a" when the "answer" is not the same, in the "drop" tone to be heavier. This is the "stress" described above.

So what is the number of beats per bar? Do you still remember the "44 Beats" and "43 beats" that were mentioned in the primary school music class?

44 beats, four notes for a beat, four beats per bar; 43 beats a beat of four notes, three beats per bar.

And as an example of this music, is a 44 beats of music, that is, a tick for a beat, each bar has four tick, each tick is a four-minute note.

Note that the four-minute note here is not the same thing as the four-minute shot above. The length of the X-Beat is the length of the 1/x beat, and the X-note length is the length of a full-note of x per cent.

One sentence is: A tempo corresponds to an X-note, and Y X-Points form a subsection,

The rhythm of this section is an XY beat, which is recorded as a y/x on the score.

Generally speaking, most pop music uses 4/4 beats, the waltz uses 3/4 beats (Bang cha), the few music uses the other pat.

On the top of the editor, the white line is a tap line, the white parallel bars are accented, and the red ones are the two-point lines.

Summary
Just sort it out. You can tell that a music has at least one rhythm, and each rhythm contains BPM, start time, and number of beats per bar .

It pulls a bunch of music-related knowledge. What's the point of saying that? The point is that it can show the rhythm of a piece of music in mathematical form.

For example: if we know that a 3/4-beat BPM is 120, then you can tell that the time of a beat is 60000/120 = 500 milliseconds, and that the length of a bar is 500x3 = 1500 milliseconds.

Since all the notes (objects) must appear on the split, it is possible to figure out the time of the object as long as the rhythm is relative to the start of the music and the index of the tempo in which the object is located.

Another example: the same music, the known rhythm is starting from the beginning of the song to play 233 milliseconds after the first shot after the first four minutes relative to the time the song began to play:

　　　　233 + ((5-1) x1500) + + (1x (500/4)) = 6858 ms

When expressed in mathematical form, any note on a split-beat can be used to express and calculate time in this form.

Conversely, it is possible to calculate the corresponding bars and beats according to the playing time.

The subsequent implementation of the program is more convenient. When you drag and drop an object, you know which line is closest to the coordinates of the object, and then you can know the time of the horizontal line.

Then I have to disappear for a while, ready to get a big story. Yes, I am going to start a business with a friend, no dream, what is the difference with salted fish? Don't embarrass yourself!

　　

The core principle of the Spectrum Editor--What is the rhythm of music