Add AudioAnalyzeRMS (thanks sgorpi)

Audio.h

 #include "analyze_tonedetect.h"
 #include "analyze_notefreq.h"
 #include "analyze_peak.h"
+#include "analyze_rms.h"
 #include "control_sgtl5000.h"
 #include "control_wm8731.h"
 #include "control_ak4558.h"

analyze_rms.cpp

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+
+#include "analyze_rms.h"
+#include <arm_math.h>
+
+void AudioAnalyzeRMS::update(void)
+{
+	audio_block_t *block;
+	int16_t rmsResult;
+
+	block = receiveReadOnly();
+	if (!block) {
+		return;
+	}
+
+	// not reinventing the wheel:
+	// use DSP packed 32i instructions as found in arm_math.h, with 64b accumulator
+	arm_rms_q15(block->data, AUDIO_BLOCK_SAMPLES, &rmsResult); // seems to use ~2% CPU
+	lastRMS = rmsResult; // prevent threading issues
+	// for optimization, one could re-implement arm_rms_q15 to do the sqrt on read().
+	// This way, the rms in dB could also be implemented faster:
+	// Instead of 20*log10(sqrt(MSerror)), one could do write 10*log10(MSerror)
+
+	new_output = true;
+	release(block);
+}
+

analyze_rms.h

+/* Audio Library for Teensy 3.X
+ * Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
+ *
+ * Development of this audio library was funded by PJRC.COM, LLC by sales of
+ * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
+ * open source software by purchasing Teensy or other PJRC products.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice, development funding notice, and this permission
+ * notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef analyze_rms_h_
+#define analyze_rms_h_
+
+#include "AudioStream.h"
+
+class AudioAnalyzeRMS : public AudioStream
+{
+private:
+	audio_block_t *inputQueueArray[1];
+	volatile bool new_output;
+	int16_t lastRMS;
+
+public:
+	AudioAnalyzeRMS(void) : AudioStream(1, inputQueueArray) {
+		lastRMS = 0;
+	}
+
+	bool available(void) {
+		__disable_irq();
+		bool flag = new_output; // we don't reset new_output here, because if you don't read it, 
+		//it'll still be available on the next call of available() 
+		// (different from AnalyzePeak behavior, which resets it in available())
+		__enable_irq();
+		return flag;
+	}
+
+	float read(void) {
+		__disable_irq();
+		int rms = lastRMS;
+		new_output = false; // we can always set the new_output to false, even if it was false already
+		__enable_irq();
+		
+		return rms / 32767.0;
+	}
+
+	virtual void update(void);
+};
+
+#endif
+

examples/Analysis/PeakAndRMSMeterStereo/PeakAndRMSMeterStereo.ino

+/* Adaptation of Stereo peak meter example, including RMS.
+assumes Audio adapter but just uses terminal so no more parts required.
+
+This example code is in the public domain
+*/
+
+#include <Audio.h>
+#include <Wire.h>
+#include <SPI.h>
+#include <SD.h>
+#include <SerialFlash.h>
+
+const int myInput = AUDIO_INPUT_LINEIN;
+// const int myInput = AUDIO_INPUT_MIC;
+
+AudioInputI2S        audioInput;         // audio shield: mic or line-in
+AudioAnalyzePeak     peak_L;
+AudioAnalyzePeak     peak_R;
+AudioAnalyzeRMS      rms_L;
+AudioAnalyzeRMS      rms_R;
+AudioOutputI2S       audioOutput;        // audio shield: headphones & line-out
+
+AudioConnection c1(audioInput, 0, peak_L, 0);
+AudioConnection c2(audioInput, 1, peak_R, 0);
+AudioConnection c3(audioInput, 0, rms_L, 0);
+AudioConnection c4(audioInput, 1, rms_R, 0);
+AudioConnection c5(audioInput, 0, audioOutput, 0);
+AudioConnection c6(audioInput, 1, audioOutput, 1);
+
+AudioControlSGTL5000 audioShield;
+
+
+void setup() {
+  AudioMemory(6);
+  audioShield.enable();
+  audioShield.inputSelect(myInput);
+  audioShield.volume(0.5);
+  Serial.begin(9600);
+}
+
+// for best effect make your terminal/monitor a minimum of 62 chars wide and as high as you can.
+
+elapsedMillis fps;
+uint8_t cnt=0;
+
+void loop() {
+  if(fps > 24) {
+    if (peak_L.available() && peak_R.available() && rms_L.available() && rms_R.available()) {
+      fps=0;
+      uint8_t leftPeak = peak_L.read() * 30.0;
+      uint8_t rightPeak = peak_R.read() * 30.0;
+      uint8_t leftRMS = rms_L.read() * 30.0;
+      uint8_t rightRMS = rms_R.read() * 30.0;
+
+      for (cnt=0; cnt < 30-leftPeak; cnt++) {
+        Serial.print(" ");
+      }
+      while (cnt++ < 29 && cnt < 30-leftRMS) {
+        Serial.print("<");
+      }
+      while (cnt++ < 30) {
+        Serial.print("=");
+      }
+      
+      Serial.print("||");
+      
+      for(cnt=0; cnt < rightRMS; cnt++) {
+        Serial.print("=");
+      }
+      for(; cnt < rightPeak; cnt++) {
+        Serial.print(">");
+      }
+      while(cnt++ < 30) {
+        Serial.print(" ");
+      }
+      Serial.print(AudioProcessorUsage());
+      Serial.print("/");
+      Serial.print(AudioProcessorUsageMax());
+      Serial.println();
+    }
+  }
+}

gui/index.html

 		{"type":"AudioFilterFIR","data":{"defaults":{"name":{"value":"new"}},"shortName":"fir","inputs":1,"outputs":1,"category":"filter-function","color":"#E6E0F8","icon":"arrow-in.png"}},
 		{"type":"AudioFilterStateVariable","data":{"defaults":{"name":{"value":"new"}},"shortName":"filter","inputs":2,"outputs":3,"category":"filter-function","color":"#E6E0F8","icon":"arrow-in.png"}},
 		{"type":"AudioAnalyzePeak","data":{"defaults":{"name":{"value":"new"}},"shortName":"peak","inputs":1,"outputs":0,"category":"analyze-function","color":"#E6E0F8","icon":"arrow-in.png"}},
+		{"type":"AudioAnalyzeRMS","data":{"defaults":{"name":{"value":"new"}},"shortName":"rms","inputs":1,"outputs":0,"category":"analyze-function","color":"#E6E0F8","icon":"arrow-in.png"}},
 		{"type":"AudioAnalyzeFFT256","data":{"defaults":{"name":{"value":"new"}},"shortName":"fft256","inputs":1,"outputs":0,"category":"analyze-function","color":"#E6E0F8","icon":"arrow-in.png"}},
 		{"type":"AudioAnalyzeFFT1024","data":{"defaults":{"name":{"value":"new"}},"shortName":"fft1024","inputs":1,"outputs":0,"category":"analyze-function","color":"#E6E0F8","icon":"arrow-in.png"}},
 		{"type":"AudioAnalyzeToneDetect","data":{"defaults":{"name":{"value":"new"}},"shortName":"tone","inputs":1,"outputs":0,"category":"analyze-function","color":"#E6E0F8","icon":"arrow-in.png"}},
 	</div>
 </script>
 
+<script type="text/x-red" data-help-name="AudioAnalyzeRMS">
+	<h3>Summary</h3>
+	<p>Track the signal RMS amplitude.  Useful for
+		audio level response projects, and general troubleshooting.</p>
+	<h3>Audio Connections</h3>
+	<table class=doc align=center cellpadding=3>
+		<tr class=top><th>Port</th><th>Purpose</th></tr>
+		<tr class=odd><td align=center>In 0</td><td>Signal to analyze</td></tr>
+	</table>
+	<h3>Functions</h3>
+	<p class=func><span class=keyword>available</span>();</p>
+	<p class=desc>Returns true if new RMS data is available.
+	</p>
+	<p class=func><span class=keyword>read</span>();</p>
+	<p class=desc>Read the new RMS value.
+		Return is from 0.0 to 1.0.
+	</p>
+	<h3>Examples</h3>
+	<p class=exam>File &gt; Examples &gt; Audio &gt; Analysis &gt; PeakAndRMSMeterStereo</p>
+	</p>
+	<h3>Notes</h3>
+	<p></p>
+</script>
+<script type="text/x-red" data-template-name="AudioAnalyzeRMS">
+	<div class="form-row">
+		<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
+		<input type="text" id="node-input-name" placeholder="Name">
+	</div>
+</script>
+
 <script type="text/x-red" data-help-name="AudioAnalyzeFFT256">
 	<h3>Summary</h3>
 	<p>Compute a 256 point Fast Fourier Transform (FFT) frequency analysis,
 
 <script type="text/x-red" data-help-name="AudioControlAK4558">
 	<h3>Summary</h3>
-	<p>Control the AK4558 chip on the <a href="https://hackaday.io/project/8567-hifi-audio-codec-module" target="_blank">HiFi Audio CODEC Module</a> 
+	<p>Control the AK4558 chip on the <a href="https://hackaday.io/project/8567-hifi-audio-codec-module" target="_blank">HiFi Audio CODEC Module</a>
 	in slave mode, where the Teensy controls all I2S timing.</p>
 	<h3>Audio Connections</h3>
 	<p>This object has no audio inputs or outputs.  Separate I2S objects

keywords.txt

 AudioAnalyzeFFT256	KEYWORD2
 AudioAnalyzeFFT1024	KEYWORD2
 AudioAnalyzePeak	KEYWORD2
+AudioAnalyzeRMS	KEYWORD2
 AudioAnalyzePrint	KEYWORD2
 AudioAnalyzeToneDetect	KEYWORD2
 AudioAnalyzeNoteFrequency	KEYWORD2