Updated techniques for working with tempo and meters

include/techniques-for-working-with-tempo-and-meter.html

@@ -1,84 +1,147 @@
 
-<h3>Techniques </h3>
+<h2>Matching a recorded tempo with a tempo ramp</h2>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_1.png" alt="Initial state">
+  <figcaption>Initial state.</figcaption>
+</figure>
 
 <p>
-  As a general approach, the best way to control tempo ramps is to use them in pairs.
+As a general approach, the best way to control tempo ramps is to use them in
+pairs.
 </p>
 
 <p>
-  Let's imagine we want to match the click to a drum performance recorded in 'free time'.
+One typical use of tempo ramps is to match the click to a drum performance recorded in
+'free time', like in the (admittedly bad) 4/4 exemple on the left.
+</p>
+
+<h3 class="clear">Step 1 : First meter</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_2.png" alt="Step 1/5">
+  <figcaption>Placing the first meter</figcaption>
+</figure>
+
+<p>
+The first thing needed is determining where the first beat is in the recording
+and <kbd class="mouse">left</kbd> dragging the first meter to that position.
+</p>
+
+<h3 class="clear">Step 2 : Locating the <em>n</em>th bar</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_3.png" alt="Step 2/5">
+  <figcaption>Locating a known beat</figcaption>
+</figure>
+
+<p>
+Now the first click will be in time with the first beat. By listening to the recorded
+drums, the position of bar <em>n</em> (here, 9th beat, 3rd bar) is visually located (the
+playhead may be moved to this location to "pin" it).
+</p>
+
+<h3 class="clear">Step 3 : Aligning the ruler with the tempo</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_4.png" alt="Step 3/5">
+  <figcaption>Matching the tempi</figcaption>
+</figure>
+
+<p>
+Holding the constraint modifier (<kbd class="mod3n"></kbd> by default), the third
+bar marker in the BBT ruler is dragged at the position of the third bar in the
+recording (where the playhead is located). This drag can be done either in the Meter
+or in the Tempo rulers. The tempo (on the first and only tempo marker) reflects
+the new value based on this change.
 </p>
 
 <p>
-  The first thing we need to do is determine where the first beat is. Drag the first meter to that position.
+The click now matches the first 8 beats, but after that it can wander off, which
+will be reflected in the tempo lines thet won't quite match the drum hits.
+</p>
+
+<h3 class="clear">Step 4 : Placing a new tempo marker</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_5.png" alt="Step 4/5">
+  <figcaption>Creating a tempo marker</figcaption>
+</figure>
+
+<p>
+A new tempo marker is placed on the last position where the click matches the
+recorded audio, by <kbd class="mod1n"></kbd>-clicking the Tempo ruler. This will
+"anchor" the value of the tempo at that position.
+</p>
+
+<h3 class="clear">Step 5 : Placing another tempo marker at the <em>n</em>th beat</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_6.png" alt="Step 5/5">
+  <figcaption>Placing another marker</figcaption>
+</figure>
+
+<p>
+Another tempo marker is placed <em>n</em> beats after the previous marker (here,
+4 beats, 1 bar).
+</p>
+
+
+<h3 class="clear">Step 6 : Changing the tempo to a new value</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_7.png" alt="Step 5/5">
+  <figcaption>Adjusting the tempo</figcaption>
+</figure>
+
+<p>
+Now, <kbd class="mod3n"></kbd>-dragging any beat <strong>after</strong> the second
+new tempo marker will allow to align the drum audio and tempo after the second marker.
+</p>
+
+<h3 class="clear">Step 7 : Ramping the tempo change</h3>
+
+<figure class="left">
+  <img class="mini" src="/images/tempo-ramp_8.png" alt="Step 5/5">
+  <figcaption>Ramping the change</figcaption>
+</figure>
+
+<p>
+Although it may be unnecessary in some cases where the tempo changes abruptly, most
+of the time, the tempo change is progressive in time, like an instrumentist drifting in tempo.
+In those cases, the tempo change should be progressive too, and Ardour allows that
+by ramping the tempo change.
 </p>
 
 <p>
-  Now the first click will be in time with the first beat. To get all the other beats to align, we listen to the drums and visually locate the position of bar 4. You may wish to place the playhead here.
+<kbd class="mouse">right</kbd> clicking the first tempo marker, a menu appears,
+allowing to <kbd class="menu">Ramp to Next</kbd>. This will make the tempo
+between the two markers linearly change from the first marker's value to the
+second's.
 </p>
 
 <p>
-  We then locate bar 4 in the BBT ruler and while holding the constraint modifier, drag it to bar 4 in the drum performance.
+Again, some time later the click will probably drift again, so the same technique
+has to be repeated: adding two new tempos and dragging the BBT ruler
+<strong>after</strong> the newest tempo so that the beats align with the audio
+again.
 </p>
 
 <p>
-  We notice that the click now matches the first 4 bars, but after that it wanders off. You will see this reflected in the tempo lines.. they won't quite match the drum hits. We now locate the earliest position where the click doesn't match, and place a new tempo just before this. Two bars later, place another new tempo.
+In a general sense, adding tempo markers in pairs allows to 'pin' the tempo at the
+marker's location while moving further to the right.
+</p>
+
+<h2>Other use cases</h2>
+
+<p>
+Audio locked meters can be useful when composing, as they allow a continuous
+piece of music to be worked on in isolated segments, preventing the listening
+fatigue of a fixed form. Reassembly is left as an excercise for the reader.
 </p>
 
 <p>
-  Now while dragging any beat <strong>after</strong> the second new tempo, watch the drum audio and tempo lines until they align.
+Tempo ramps can also be used in a video context, e.g. for an accelerando,
+by snapping to TC frames and drag the ruler so that a bar ends up on a significant
+video frame.
 </p>
-
-<p class="note">
-  Notice what is happening here: the tempo previous to your mouse pointer is being changed so that the beat you grabbed aligns with the pointer. Notice that the tempo lines previous to the changed one also move. This is because the previous tempo is ramping <strong>to</strong> the tempo you are changing. Look further to the left. The tempo lines in the first four bars do not move.
-</p>
-
-<p>
-  Again, some time later the click will not align. I didn't say this was easy.
-</p>
-
-<p>
-  Repeat the same technique: add two new tempos and drag the BBT ruler <strong>after</strong> the newest tempo so that the beats align with the audio again.
-</p>
-
-<p>
-  In a general sense, adding tempo markers in pairs allows you to 'pin' your previous work while you move further to the right.
-</p>
-
-<h3>Another use case: matching accelerando</h3>
-
-<p>
-  Imagine you have some video and have located where your music cue begins. Move the first meter to that frame (you may snap to TC frames, but not music with an audio locked meter).
-</p>
-
-<p>
-  Find a starting tempo by listening to the click while you drag the meter's tempo vertically using the constraint modifier.
-</p>
-
-<p>
-  You have the playhead at point where the dude slams the phone down, and your idea was that 4|1|0 would be good for this, but you want an accelerando to that point.
-</p>
-
-<p>
-  Add a tempo at bar 4.
-</p>
-
-<p>
-  Holding down the constraint modifier, and with snap set to 'TC Frames', grab the BBT ruler just <strong>after</strong> 4|1|0. Drag the ruler so that 4|1|0 snaps to the 'phone' frame.
-</p>
-
-<p class="note">
-  Notice what happened: The second tempo was changed.<br>
-  You had set a musical position for the second tempo marker. It was not aligned with the frame you wanted, so you dragged the BBT ruler, making the second tempo provide enough pulses over the ramp for 4|1|0 to align with the desired frame.
-</p>
-
-<p>
-  If the ramp doesn't feel right, you may add more points within it and keep adjusting beat positions in a similar manner.
-</p>
-
-<h3>General</h3>
-
-<p>
-  Audio locked meters can be useful when composing, as they allow a continuous piece of music to be worked on in isolated segments, preventing the listening fatigue of a fixed form. Reassembly is left as an excercise for the reader.
-</p>
-