I am watching this video:
It says there are some triplets with more than three values or less than three values.
For instance:
In the video, it demonstrates how I calculate the total rhythmic value of that kind of triplets, but when I'm about to play the triplet, what exactly is the duration of each note? Should I just split them by the count of notes? Or should I follow some other rules?
I have always, as you say, "split them by the count of notes." It's a multi-step process of:
Let's take your first unequal example of an eighth, two sixteenths, and an eighth. Our first step is to ignore the triplet aspect of this rhythm and focus on the eighth, two sixteenths, and the eighth. The total duration of these notes will be equal to three of some note value. The eighth, two sixteenths, and eighth are equivalent to 1.5 quarter notes, or three eighth notes. The eighth note is thus the main indicator for this triplet.
A triplet consists of three note values that take place in the span of two. So this first triplet, because it's written in the duration of three eighth notes, will actually last the duration of only two eighth notes (i.e., a quarter note).
From there, it's just a question of subdividing. Practice your "regular" eighth-note triplet, then try subdividing each of the eighth notes into sixteenths. Finally, remove the extraneous sixteenths and perform the eighth, two sixteenths, eighth triplet as written.
I know how cumbersome this answer is, so let's try your second example, too. The triplet has a half followed by a quarter. Let's ignore the triplet aspect and only focus on those values: a half and a quarter. Then, we know that the total value of that half and quarter is equal to three of some single note value. The half and quarter are three quarter notes in length, so the quarter note is our main rhythmic basis.
A triplet is three note values in the place of two, so this quarter-note triplet will last the duration of two quarter notes (i.e., a half note). I recommend practicing this triplet as if it were three articulated quarter notes, and then slowly removing the articulation on the second quarter note.
One more example may be helpful: a triplet of a quarter, dotted quarter, and eighth. Determine the answer yourself, then click the spoiler text to reveal the answer.
The quarter, dotted quarter, and eighth are equivalent to three quarter notes. This triplet will thus last the span of two quarter notes, or a half note.
Whatever values of notes, regardless of tempo, they're all relative to each other. As in - a crotchet is always twice the length of a quaver, a minim always twice the length of a crotchet, and so on, in the same piece, at the same tempo.
So the same concept will occur within tuplets, whatever they're made up of. Your example of a minim and a crotchet within a triplet mark: the minim will always be twice as long as the crotchet, just that the both notes together will have the same timing as one minim. It's as simple as that. That's if the music keeps absolute, strict time. Which some music does, some doesn't. But as a start point, keep it mathematically straightforward, as I indicate, and you won't go far wrong.
Quaver= 1/8, crotchet= 1/4 and minim =1/2 notes, for those unfamiliar with the terminology! And that probably helps - 1/2 is twice as big as 1/4, etc...
