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				<h1>DSP Library</h1>
				<address><a href="https://signalsmith-audio.co.uk">Signalsmith Audio</a></address>
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			<p>This is a set of <strong>C++11</strong> header-only classes/templates to support certain DSP tasks (mostly audio).</p>
			<p>It's still growing, but currently includes:</p>
			<ul>
				<li>Delay tools (circular buffers, single/multi-channel delay-lines)</li>
				<li>Interpolators (Lagrange, polyphase, Kaiser-sinc)</li>
				<li>Envelope tools (e.g. box-filter, peak-hold)</li>
				<li>FFT and spectral processing (including multi-channel STFT)</li>
			</ul>

			<h2>How to use</h2>
			<p>Clone using Git:</p>
			<figure><pre><code class="full clipboard-copy">
				git clone https://signalsmith-audio.co.uk/code/dsp.git
			</code></pre><figcaption>There's also a <a href="https://github.com/signalsmith-audio/dsp" target="_blank">GitHub mirror</a></figcaption></figure>
			<p>Include the appropriate header file, and start using classes:</p>
			<figure><pre class="language-cpp"><script type="code">
				#include "dsp/delay.h";

				using Delay = signalsmith::delay::Delay<float>;
				Delay delayLine(1024);
			</script></pre></figure>
			<h3>API docs</h3>
			<p>Check out the <a href="html/modules.html">API documentation (Doxygen)</a> for detailed information.</p>

			<h2>Testing</h2>
			<p>Tests (and scripts to plot graphs etc.) are in a separate repository, to keep the main repo neater:</p>
			<figure><pre><code class="full clipboard-copy">
				git clone https://signalsmith-audio.co.uk/code/dsp-doc.git
			</code></pre><figcaption>There's a <a href="https://github.com/signalsmith-audio/dsp-doc" target="_blank">GitHub mirror</a> for this too</figcaption></figure>
			<h3>Goals</h3>
			<p>Where reasonable, the tests should measure actual output quality (not just basic correctness and smoke-tests).</p>
			<p>For example, here's the aliasing/accuracy performance of a delay line with windowed-sinc interpolation:</p>
			<figure><img src="html/interpolator-KaiserSincN.svg"></figure>
			<p>The automated tests check this performance for various input bandwidths, using a table like this:</p>
			<figure><pre><code class="language-cpp">
				// A table of acceptable limits for the 20-point windowed-sinc
				double bandwidth[] = {90, 80, 50, 25, 12.5};
				double aliasing[] = {-20.5, -61, -70.5, -76, -77.5};
				double ampLow[] = {-2, -0.02, -0.01, -0.01, -0.01};
				double ampHigh[] = {0.02, 0.02, 0.01, 0.01, 0.01};
				double delayError[] = {0.9, 0.03, 0.01, 0.01, 0.01};
			</code></pre><figcaption>Each column specifies performance for a particular input bandwidth - e.g. 25% would correspond to 4x oversampled input.</figcaption></figure>

			<h3>Running the tests</h3>
			<p>To run the tests:</p>
			<figure><pre><code>make test</code></figure>
			<p>To run just the tests in <code>tests/delay/</code> (or similar):</p>
			<figure><pre><code>make test-delay</code></pre></figure>
			<p>There are a few other targets (e.g. for plotting graphs) - check the <code>Makefile</code> if you're curious.</p>

			<h2>License</h2>
			<p>The main library is <a href="https://choosealicense.com/licenses/mit/">MIT licensed</a> (see <code>LICENSE.txt</code> in the main repo), but the tests, docs and support scripts are licensed differently (just for developing/testing the library).</p>
			<p>We're pretty flexible though - if you need something else, <a href="https://signalsmith-audio.co.uk/contact">get in touch</a>.</p>

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