Add support for fmt's extrabyte

Added, in readheader internal API, a logic to ignore the extrabyte in fmt header's chunk in WAV file.

Author: Rocketct

src/SDWaveFile.cpp

@@ -39,6 +39,8 @@ struct WaveFileHeader {
   } subChunk2;
 } __attribute__((packed));
 
+  struct WaveFileHeader header;
+
 SDWaveFile::SDWaveFile() : 
   SDWaveFile(NULL)
 {
@@ -173,6 +175,55 @@ int SDWaveFile::begin()
   return 1;
 }
 
+int SDWaveFile::findData() {
+  uint8_t byteread;
+  int count = 0, fileSize;
+  uint32_t size = 0, data;
+  uint8_t buffer[] = {0, 0, 0, 0};
+
+  fileSize = _file.size() - 36;
+
+  //Read the first WAV header's chunk
+  if (_file.read(&header, 36) != 36) {
+    _file.close();
+    return -1;
+  }
+
+  //check if "data" field is present
+  while (count < fileSize) {
+    if (_file.read((void *)&byteread, 1) != 1) {
+      _file.close();
+      return -1;
+    }
+    for (int i = 0; i <= 2; i++) {
+      buffer[i] = buffer[i + 1];
+    }
+    buffer[3] = byteread;
+    count++;
+
+    if (count >= 4) {
+      data = 0;
+      data += buffer[0] << 24;
+      data += buffer[1] << 16;
+      data += buffer[2] << 8;
+      data += buffer[3];
+      //if find data field read the last header part
+      if (data == 0x64617461) {
+        if (_file.read((void *)&size, 4) != 4) {
+          _file.close();
+          return -1;
+        }
+
+        //set second WAV header's chunk and return
+        header.subChunk2.id = data;
+        header.subChunk2.size = size;
+        return 1;
+      }
+    }
+  }
+  return -1;
+}
+
 int SDWaveFile::read(void* buffer, size_t size)
 {
   uint32_t position = _file.position();
@@ -225,9 +276,7 @@ void SDWaveFile::readHeader()
     return;
   }
 
-  struct WaveFileHeader header;
-
-  if (_file.read(&header, sizeof(header)) != sizeof(header)) {
+  if (findData() == -1) {
     _file.close();
     return;
   }
@@ -238,7 +287,6 @@ void SDWaveFile::readHeader()
   header.chunkId = __REV(header.chunkId);
   header.format = __REV(header.format);
   header.subChunk1.id = __REV(header.subChunk1.id);
-  header.subChunk2.id = __REV(header.subChunk2.id);
 
   if (header.chunkId != 0x52494646) { // "RIFF"
     return;
@@ -256,11 +304,6 @@ void SDWaveFile::readHeader()
     return;
   }
 
-  if (header.subChunk1.size != 16 || header.subChunk1.audioFormat != 1) {
-    // not PCM
-    return;
-  }
-
   if (header.subChunk2.id != 0x64617461) { // "data"
     return;
   }

src/SDWaveFile.h

@@ -55,6 +55,7 @@ class SDWaveFile : public SoundFile
 
 private:
   void readHeader();
+  int findData();
 
 private:
   bool _headerRead;