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

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<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.
</p>
<p>
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 example on the left.
</p>
<h3 class="clear">Step 1: First time signature</h3>
<figure class="left">
<img class="mini" src="/images/tempo-ramp_2.png" alt="Step 1/5">
<figcaption>Placing the first time signature</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 time signature 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, may be
changed in <kbd class="menu">Preferences &gt; Editor &gt; Modifiers</kbd>),
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 Time Signature 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 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>
<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>
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>
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 time signatures 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>
Tempo ramps can also be used in a video context, e.g. for an accelerando, by
snapping to TC frames and dragging the ruler so that a bar ends up on a
significant video frame.
</p>