WEBVTT 00:00:00.000 --> 00:00:02.485 align:middle line:90% [SQUEAKING] 00:00:02.485 --> 00:00:03.976 align:middle line:90% [RUSTLING] 00:00:03.976 --> 00:00:07.455 align:middle line:90% [CLICKING] 00:00:07.455 --> 00:00:09.442 align:middle line:90% 00:00:09.442 --> 00:00:11.400 align:middle line:84% MICHAEL SCOTT ASATO CUTHBERT: Hello, everybody. 00:00:11.400 --> 00:00:13.442 align:middle line:84% One of the great things about making these videos 00:00:13.442 --> 00:00:16.010 align:middle line:84% is that we can introduce small concepts that otherwise 00:00:16.010 --> 00:00:17.460 align:middle line:90% might fall through the cracks. 00:00:17.460 --> 00:00:20.060 align:middle line:84% So I want to introduce the concept of ties 00:00:20.060 --> 00:00:22.850 align:middle line:84% and how we represent them in music21 00:00:22.850 --> 00:00:26.010 align:middle line:84% and how you might represent them in your own projects. 00:00:26.010 --> 00:00:30.410 align:middle line:84% So let's go ahead and import from music21 note, stream, 00:00:30.410 --> 00:00:32.670 align:middle line:90% and the new tie module. 00:00:32.670 --> 00:00:37.260 align:middle line:84% And we can go ahead and create a stream of a measure. 00:00:37.260 --> 00:00:40.040 align:middle line:90% We'll call it m. 00:00:40.040 --> 00:00:43.400 align:middle line:90% And let's create two notes. 00:00:43.400 --> 00:00:46.110 align:middle line:84% And doesn't really matter what you make them. 00:00:46.110 --> 00:00:51.440 align:middle line:84% Just make sure that they're the same pitch because otherwise we 00:00:51.440 --> 00:00:53.330 align:middle line:90% can't tie them. 00:00:53.330 --> 00:00:54.750 align:middle line:90% That's pretty good. 00:00:54.750 --> 00:01:01.130 align:middle line:84% And we'll say we'll create a time signature. 00:01:01.130 --> 00:01:12.680 align:middle line:84% That's why I usually eventually will import star but 2/4. 00:01:12.680 --> 00:01:22.790 align:middle line:84% And let's put m.append(ts), m.append(n1). 00:01:22.790 --> 00:01:26.180 align:middle line:84% Actually, we can just put more than one thing in, 00:01:26.180 --> 00:01:30.050 align:middle line:90% and we'll show these two notes. 00:01:30.050 --> 00:01:35.310 align:middle line:84% And now while it's doing that, we'll go ahead and get n1's. 00:01:35.310 --> 00:01:40.260 align:middle line:84% tie will be a new tie.tie object, and it'll be a start. 00:01:40.260 --> 00:01:45.030 align:middle line:84% n2's tie will be a tie.tie object, and it will be stop. 00:01:45.030 --> 00:01:48.270 align:middle line:84% And now when we show the measure, 00:01:48.270 --> 00:01:54.140 align:middle line:84% we have what we should have written as a half note, right? 00:01:54.140 --> 00:01:58.910 align:middle line:84% But we can go ahead, and let's create another measure. 00:01:58.910 --> 00:02:05.530 align:middle line:84% And here's, of course, where we would be more likely to do this 00:02:05.530 --> 00:02:07.910 align:middle line:90% at, make a quarter rest. 00:02:07.910 --> 00:02:10.449 align:middle line:84% That's the default, but just to show it. 00:02:10.449 --> 00:02:16.370 align:middle line:84% And so we can, by the way, put objects in more than one stream. 00:02:16.370 --> 00:02:21.730 align:middle line:84% And so this is something that's going to happen sometimes. 00:02:21.730 --> 00:02:26.680 align:middle line:84% We'll put the first note in, and now we'll create m3 is 00:02:26.680 --> 00:02:30.640 align:middle line:84% a stream.measure and m3.append(n2). 00:02:30.640 --> 00:02:36.160 align:middle line:90% 00:02:36.160 --> 00:02:42.760 align:middle line:84% Oh, you know I really do care about having all our measures 00:02:42.760 --> 00:02:47.170 align:middle line:90% appear, and p is a stream.part. 00:02:47.170 --> 00:02:55.690 align:middle line:84% We'll go ahead and put inside the stream m2 and append(m3). 00:02:55.690 --> 00:02:59.460 align:middle line:84% And let's go ahead and show that. 00:02:59.460 --> 00:03:02.470 align:middle line:84% Great, so this shows how ties might work. 00:03:02.470 --> 00:03:03.430 align:middle line:90% Now, here's the thing. 00:03:03.430 --> 00:03:10.230 align:middle line:84% If we do for n in, well, p.recurse.notes, 00:03:10.230 --> 00:03:16.020 align:middle line:84% and we try to figure out how many notes there are. 00:03:16.020 --> 00:03:17.980 align:middle line:84% Well, it looks like there's three of them. 00:03:17.980 --> 00:03:20.610 align:middle line:84% But if we listen to this piece, obviously we're 00:03:20.610 --> 00:03:22.300 align:middle line:90% just going to hear two notes. 00:03:22.300 --> 00:03:23.710 align:middle line:90% So what can we do? 00:03:23.710 --> 00:03:26.170 align:middle line:90% Well, we can create a new part. 00:03:26.170 --> 00:03:29.550 align:middle line:84% We'll say p2 equals part.stripTies. 00:03:29.550 --> 00:03:32.640 align:middle line:90% 00:03:32.640 --> 00:03:35.860 align:middle line:90% And now if we do for n-- 00:03:35.860 --> 00:03:38.010 align:middle line:84% well, actually, let's show this, and we'll 00:03:38.010 --> 00:03:39.660 align:middle line:90% show it as a text file. 00:03:39.660 --> 00:03:45.520 align:middle line:84% We'll see here that we only have two notes now. 00:03:45.520 --> 00:03:49.500 align:middle line:84% But in this next measure, this note, 00:03:49.500 --> 00:03:53.640 align:middle line:84% the C only begins one quarter note in. 00:03:53.640 --> 00:03:56.280 align:middle line:84% So we've reduced-- what we've done 00:03:56.280 --> 00:04:00.300 align:middle line:84% is we've taken these two E's that are tied, 00:04:00.300 --> 00:04:03.850 align:middle line:84% and we've replaced them with one half note. 00:04:03.850 --> 00:04:07.920 align:middle line:90% In fact, we can look at this. 00:04:07.920 --> 00:04:13.060 align:middle line:90% That's our note and duration. 00:04:13.060 --> 00:04:14.360 align:middle line:90% It's a half note. 00:04:14.360 --> 00:04:17.279 align:middle line:90% 00:04:17.279 --> 00:04:22.470 align:middle line:84% When we strip ties, we create things sometimes 00:04:22.470 --> 00:04:25.600 align:middle line:84% that don't really musically exist. 00:04:25.600 --> 00:04:29.790 align:middle line:84% We have a measure that has a time signature of 2/4, 00:04:29.790 --> 00:04:32.370 align:middle line:84% has a quarter rest, and then it has a half note in it. 00:04:32.370 --> 00:04:34.150 align:middle line:90% That really can't work. 00:04:34.150 --> 00:04:39.120 align:middle line:84% So you can't really do p2.show and expect 00:04:39.120 --> 00:04:42.700 align:middle line:84% something that looks right because that just wouldn't work. 00:04:42.700 --> 00:04:49.330 align:middle line:84% But instead, in terms of iterating for n in p2.recurse, 00:04:49.330 --> 00:04:53.970 align:middle line:84% we'll say, .notesAndRests, [MUMBLES]. 00:04:53.970 --> 00:05:01.320 align:middle line:84% Let's print n's offset, and we can see that. 00:05:01.320 --> 00:05:04.580 align:middle line:84% And we can even do measure Number ha. 00:05:04.580 --> 00:05:07.380 align:middle line:84% This would totally have saved you time on problem set 3, 00:05:07.380 --> 00:05:08.690 align:middle line:90% wouldn't it have? 00:05:08.690 --> 00:05:14.678 align:middle line:84% Oops, we'll go back and call these number equals 1, 00:05:14.678 --> 00:05:15.803 align:middle line:90% measures are auto numbered. 00:05:15.803 --> 00:05:19.280 align:middle line:90% 00:05:19.280 --> 00:05:23.120 align:middle line:84% And now when we go back here, we can 00:05:23.120 --> 00:05:26.630 align:middle line:90% see the rest is in measure one. 00:05:26.630 --> 00:05:30.060 align:middle line:84% Then note E is in measure one at offset 1. 00:05:30.060 --> 00:05:33.160 align:middle line:90% In fact, let's print it's-- 00:05:33.160 --> 00:05:38.990 align:middle line:90% 00:05:38.990 --> 00:05:42.230 align:middle line:84% we should see that E is in measure 1 at offset 1 00:05:42.230 --> 00:05:46.370 align:middle line:84% is half note, and the C is in measure 2 at offset 1 00:05:46.370 --> 00:05:49.040 align:middle line:90% is a quarter note. 00:05:49.040 --> 00:05:51.950 align:middle line:84% I'd make this longer, but that's basically 00:05:51.950 --> 00:05:53.490 align:middle line:90% all there is to do with ties. 00:05:53.490 --> 00:05:55.780 align:middle line:90% Thanks for listening. 00:05:55.780 --> 00:05:58.000 align:middle line:90%