76 lines
2.7 KiB
HTML
76 lines
2.7 KiB
HTML
<h2>Stretching</h2>
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<p>
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When you load an audio clip into a trigger slot, Ardour applies some
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heuristics to estimate its temo in beats per minute. Unless a metadata
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in the file source provides information,
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<a href="https://github.com/breakfastquay/minibpm">minibpm</a> is used
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to analyze and detect the file's BPM.
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</p>
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<p>
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After tempo is estimated, the clip is time-stretched to match the
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session's tempo map. This means that should session's tempo change over
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time (in either ramped or constant mode), all audio clips will be
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re-stretched to accomodate for that.
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</p>
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<p>
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Disabling stretching when original clip's tempo doesn't match that of the
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session will most of the times make the clip audibly go out of sync with
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the beat.
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</p>
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<p>Stretch modes:</p>
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<p>
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Once stretching is enabled, you have several options how to apply it:
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</p>
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<ul>
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<li><dfn>Crisp</dfn> works best for sounds with fast onset like drums and percussion</li>
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<li><dfn>Smooth</dfn> is best used for sustained notes like pads</li>
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<li><dfn>Mixed</dfn> is for anything in between</li>
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</ul>
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<h2>BPM</h2>
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<p>
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This is where the estimated tempo is displayed. It can also
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be progressively divided or mutiplied by two.
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</p>
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<p>
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Supposing, session's tempo is currently 120bpm and original clip's tempo
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is 90bpm. Stretching the clip to match session's tempo will make it sound
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faster that it originally is.
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</p>
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<p>
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If the estimated clip's tempo is divided by 2, stretching the resulted
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45bpm back to 120bpm will make the clip sound faster. Vice versa,
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multiplying the original clip's tempo by 2 and then stretching it down
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from 180bpm to 120bpm will make the clip sound slower than it originally is.
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</p>
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<h2>Clip Length</h2>
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Measured in beats. Affects the bpm. FIXME
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<h2>Length in Bars</h2>
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<p>It’s a hint to help you counting. FIXME</p>
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<p>1) when a file is loaded, we infer its bpm either by minibpm's estimate, a flag in the filename, metadata (TBD) or other means</p>
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<p>2) we assume the clip must have an integer number of beats in it (simplest case is a one-bar loop with 4 beats in it)</p>
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<p>3) ...so we round to the nearest beat length, and set the tempo to *exactly* fit the sample-length into the assumed beat-length</p>
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<p>4) the user may recognize a problem: "this was a 3/4 beat, which was rounded to 4 beats but it should have been 3"</p>
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<p>5) if the user changes the beat-length, then the tempo is recalculated for use during stretching</p>
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<p>6) someday, we will also allow the sample start and length to be adjusted in a trimmer, and that will also adjust the tempo</p>
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<p>7) in all cases the user should be in final control; but our "internal" value for stretching are just sample-start and BPM, end of story</p> |