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libraries/audio-tools/examples/examples-stream/streams-memory_mp3-analog/README.md

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+# Decoding a MP3 file
+
+In this example we decode a MP3 file into RAW output and send it the analog output pins. 
+
+Currently we provide multiple mp3 decoders
+- libhelix 
+- tinymp3
+
+Unfortunatly non of those are currently stable in all environments....
+
+### Output Device: Piezo Electric Element
+
+To test the output I am using piezo electric elements
+
+![DAC](https://pschatzmann.github.io/Resources/img/piezo.jpeg)
+
+It should also be possible to connect a headphone to the output pins.
+
+
+| PIEZO Left  |  ESP32       
+| ------------| --------------
+| +           |  GPIO25  
+| -           |  GND        
+
+| PIEZO2 Rigt |  ESP32       
+| ------------| --------------
+| +           |  GPIO26  
+| -           |  GND        

libraries/audio-tools/examples/examples-stream/streams-memory_mp3-analog/streams-memory_mp3-analog.ino

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+/**
+ * @file stream-memory_mp3-analog.ino
+ * @author Phil Schatzmann
+ * @brief decode MP3 stream and output as out signal
+ * @version 0.1
+ * @date 2021-01-24
+ * 
+ * @copyright Copyright (c) 2021
+ 
+ */
+
+// install https://github.com/pschatzmann/arduino-libhelix.git
+
+#include "AudioTools.h"
+#include "AudioTools/AudioCodecs/CodecMP3Helix.h"
+#include "BabyElephantWalk60_mp3.h"
+
+
+MemoryStream mp3(BabyElephantWalk60_mp3, BabyElephantWalk60_mp3_len);
+AnalogAudioStream analog;  // Analog output 
+EncodedAudioStream out(&analog, new MP3DecoderHelix()); // output to decoder
+StreamCopy copier(out, mp3);    // copy in to out
+
+void setup(){
+  Serial.begin(115200);
+  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);  
+
+  analog.begin(analog.defaultConfig(TX_MODE));  
+
+  // begin processing
+  out.begin();
+}
+
+void loop(){
+  if (mp3) {
+    copier.copy();
+  } else {
+    auto info = out.decoder().audioInfo();
+    LOGI("The audio rate from the mp3 file is %d", info.sample_rate);
+    LOGI("The channels from the mp3 file is %d", info.channels);
+    out.end();
+    stop();
+  }
+}