Add a compressor (kindly relicensed by Rune Holm). Fixed for now, and only to get...

[nageru] / stereocompressor.h

diff --git a/stereocompressor.h b/stereocompressor.h
new file mode 100644 (file)
index 0000000..239f284
--- /dev/null
+++ b/stereocompressor.h
@@ -0,0 +1,45 @@
+#ifndef _STEREOCOMPRESSOR_H
+#define _STEREOCOMPRESSOR_H 1
+
+// A simple compressor based on absolute values, with independent
+// attack/release times. There is no sidechain or lookahead, but the
+// peak value is shared between both channels.
+//
+// The compressor was originally written by, and is copyrighted by, Rune Holm.
+// It has been adapted and relicensed under GPLv3 (or, at your option,
+// any later version) for Nageru, so that its license matches the rest of the code.
+
+class StereoBuffer;
+
+class StereoCompressor {
+public:
+       StereoCompressor(float sample_rate)
+               : sample_rate(sample_rate) {
+               reset();
+       }
+
+       void reset() {
+               peak_level = compr_level = 0.1f;
+               scalefactor = 0.0f;
+       }
+
+       // Process <num_samples> interleaved stereo data in-place.
+       // Attack and release times are in seconds.
+       void process(float *buf, size_t num_samples, float threshold, float ratio,
+                    float attack_time, float release_time, float makeup_gain);
+
+       // Last level estimated (after attack/decay applied).
+       float get_level() { return compr_level; }
+
+       // Last attenuation factor applied, e.g. if 5x compression is currently applied,
+       // this number will be 0.2.
+       float get_attenuation() { return scalefactor; }
+
+private:
+       float sample_rate;
+       float peak_level;
+       float compr_level;
+       float scalefactor;
+};
+
+#endif /* !defined(_STEREOCOMPRESSOR_H) */