Web radio chunked demo

examples/WebRadioChunkedDemo/WebRadioChunkedDemo.ino

@@ -0,0 +1,225 @@
+/**
+ * A chunked stream handler to play web radio stations using ESP8266.
+ * It shows how to remove chunk control data from the stream to avoid the sound glitches.
+ *
+ * More technical details about chunked transfer:
+ * https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Transfer-Encoding
+ * https://en.wikipedia.org/wiki/Chunked_transfer_encoding
+ *
+ * Github discussion related to this demo:
+ * https://github.com/baldram/ESP_VS1053_Library/issues/47
+ */
+
+#include <VS1053.h>
+#ifdef ARDUINO_ARCH_ESP8266
+#include <ESP8266WiFi.h>
+#define VS1053_CS     D1
+#define VS1053_DCS    D0
+#define VS1053_DREQ   D3
+#endif
+
+#ifdef ARDUINO_ARCH_ESP32
+#include <WiFi.h>
+#define VS1053_CS     5
+#define VS1053_DCS    16
+#define VS1053_DREQ   4
+#endif
+
+// Default volume
+#define VOLUME  80
+
+VS1053 player(VS1053_CS, VS1053_DCS, VS1053_DREQ);
+WiFiClient client;
+
+const char *ssid = "TP-Link";
+const char *password = "xxxxxxxx";
+
+// this is the audio stream which uses chunked transfer
+const char *host = "icecast.radiofrance.fr";
+const char *path = "/franceculture-lofi.mp3";
+int httpPort = 80;
+
+// The buffer size 64 seems to be optimal. At 32 and 128 the sound might be brassy.
+#define BUFFER_SIZE 64
+uint8_t mp3buff[BUFFER_SIZE];
+
+uint8_t remove_chunk_control_data(uint8_t *data, size_t length);
+
+void setup() {
+  Serial.begin(115200);
+
+  // Wait for VS1053 and PAM8403 to power up
+  // otherwise the system might not start up correctly
+  delay(3000);
+
+  // This can be set in the IDE no need for ext library
+  // system_update_cpu_freq(160);
+
+  Serial.println("\n\Chunked Transfer Radio Node WiFi Radio");
+
+  SPI.begin();
+
+  player.begin();
+  player.switchToMp3Mode();
+  player.setVolume(VOLUME);
+
+  Serial.print("Connecting to SSID ");
+  Serial.println(ssid);
+  WiFi.begin(ssid, password);
+  WiFi.setAutoConnect(true);
+  WiFi.setAutoReconnect(true);
+  WiFi.reconnect();
+
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+
+  Serial.println("WiFi connected");
+  Serial.println("IP address: ");
+  Serial.println(WiFi.localIP());
+
+  Serial.print("connecting to ");
+  Serial.println(host);
+
+  if (!client.connect(host, httpPort)) {
+    Serial.println("Connection failed");
+    return;
+  }
+
+  Serial.print("Requesting stream: ");
+  Serial.println(path);
+
+  client.print(String("GET ") + path + " HTTP/1.1\r\n" + "Host: " + host + "\r\n" + "Connection: close\r\n\r\n");
+}
+
+void loop() {
+  if (!client.connected()) {
+    Serial.println("Reconnecting...");
+    if (client.connect(host, httpPort)) {
+      client.print(String("GET ") + path + " HTTP/1.1\r\n" + "Host: " + host + "\r\n" + "Connection: close\r\n\r\n");
+    }
+  }
+
+  if (client.available() > 0) {
+    uint8_t bytesread = client.read(mp3buff, BUFFER_SIZE);
+    bytesread = remove_chunk_control_data(mp3buff, bytesread);
+    player.playChunk(mp3buff, bytesread);
+  }
+}
+
+// Introduce here a new helper buffer with size of 8 bytes, to remove the chunked control bytes.
+// Variables must be aligned to avoid the Exception (9) being thrown from the ESP8266
+// See here: https://arduino-esp8266.readthedocs.io/en/latest/exception_causes.html
+// See here: https://arduino.stackexchange.com/questions/67442/nodemcu-1-0-exception-9-fatal-exception-9loadstorealignmentcause
+uint8_t __attribute__((aligned(4))) helperBuffer[8];
+uint8_t __attribute__((aligned(4))) helperBufferCount = 0;
+
+/***
+ * Removes the chunk control data from the helper buffer.
+ *
+ * Only the following chunk control bytes are removed:
+ * \r\n<byte><byte>\r\n
+ * \r\n<byte><byte><byte>\r\n
+ * \r\n<byte><byte><byte><byte>\r\n
+ *
+ */
+void remove_chunk_control_data_from_helper_buffer() {
+  if (helperBuffer[0] != '\r') {
+    // die fast
+    return;
+  }
+  if (helperBuffer[1] != '\n') {
+    // die fast
+    return;
+  }
+
+  if (helperBuffer[4] == '\r' && helperBuffer[5] == '\n') {
+    // 6 bytes length chunk control section discovered
+    // \r\n<byte><byte>\r\n
+    helperBufferCount = 2;
+    Serial.println("Removed control data: 6 bytes");
+
+    return;
+  }
+
+  if (helperBuffer[5] == '\r' && helperBuffer[6] == '\n') {
+    // 7 bytes length chunk control section discovered
+    // \r\n<byte><byte><byte>\r\n
+    helperBufferCount = 1;
+    Serial.println("Removed control data: 7 bytes");
+
+    return;
+  }
+
+  if (helperBuffer[6] == '\r' && helperBuffer[7] == '\n') {
+    // 8 bytes length chunk control section discovered
+    // \r\n<byte><byte><byte><byte>\r\n
+    helperBufferCount = 0;
+    Serial.println("Removed control data: 8 bytes");
+
+    return;
+  }
+}
+
+/***
+ * Puts a byte to the input of helper buffer and returns a byte from the output of helper buffer.
+ * In the meantime it tries to remove the chunk control data (if any available) from the buffer.
+ *
+ * @param incoming byte of the audio stream
+ * @return outgoing byte of the audio stream (if available) or -1 when no bytes available (this happens
+ * when the buffer is being populated with the data or after removal of chunk control data)
+ */
+int16_t put_through_helper_buffer(uint8_t newValue) {
+  //
+  int16_t result = -1;
+
+  if (helperBufferCount == 8) {
+    result = helperBuffer[0];
+  }
+
+  helperBuffer[0] = helperBuffer[1];
+  helperBuffer[1] = helperBuffer[2];
+  helperBuffer[2] = helperBuffer[3];
+  helperBuffer[3] = helperBuffer[4];
+  helperBuffer[4] = helperBuffer[5];
+  helperBuffer[5] = helperBuffer[6];
+  helperBuffer[6] = helperBuffer[7];
+  helperBuffer[7] = newValue;
+
+  helperBufferCount++;
+  if (helperBufferCount > 8) {
+    helperBufferCount = 8;
+  }
+
+  remove_chunk_control_data_from_helper_buffer();
+
+  return result;
+}
+
+/***
+ * Removes the chunk control data from the input audio stream. Data are written back to the input
+ * buffer and the number of bytes available (after processing) is returned.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Transfer-Encoding
+ * @see https://en.wikipedia.org/wiki/Chunked_transfer_encoding
+ *
+ * @param data a pointer to the input buffer of audio stream
+ * @param length a number of input bytes to be processed
+ * @return the number of available bytes in the input buffer after removing the chunk control data
+ */
+uint8_t remove_chunk_control_data(uint8_t *data, size_t length) {
+
+  uint8_t writeindex = 0;
+  uint8_t index = 0;
+  for (index = 0; index < lengt; index++) {
+    uint8_t input = data[index];
+    int16_t output = put_through_helper_buffer(input);
+    if (output >= 0) {
+      data[writeindex] = (uint8_t) output;
+      writeindex++;
+    }
+  }
+
+  return writeindex;
+}

src/VS1053.cpp

@@ -325,4 +325,4 @@ uint16_t VS1053::getDecodedTime() {
 void VS1053::clearDecodedTime() {
     write_register(SCI_DECODE_TIME, 0x00);
     write_register(SCI_DECODE_TIME, 0x00);
-}
+}