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

@@ -129,8 +129,8 @@ long SDWaveFile::currentTime()
 
   uint32_t position = _file.position();
 
-  if (position >= sizeof(struct WaveFileHeader)) {
-    position -= sizeof(struct WaveFileHeader);
+  if (position >= (sizeof(struct WaveFileHeader) + _headerOffset)) {
+    position -= (sizeof(struct WaveFileHeader) + _headerOffset);
   }
 
   return (position) / (_blockAlign * _sampleRate);
@@ -142,7 +142,7 @@ int SDWaveFile::cue(long time)
     return 1;
   }
 
-  long offset = (time * _blockAlign) - sizeof(struct WaveFileHeader);
+  long offset = (time * _blockAlign) - sizeof(struct WaveFileHeader) - _headerOffset;
 
   if (offset < 0) {
     offset = 0;
@@ -173,14 +173,48 @@ int SDWaveFile::begin()
   return 1;
 }
 
+int SDWaveFile::findData(int offset) {
+  uint8_t byteread;
+  int count = 0, fileSize;
+  uint32_t data;
+  uint8_t buffer[] = {0, 0, 0, 0};
+
+  fileSize = _file.size() - offset;
+
+  //check if "data" field is present
+  while (count < fileSize) {
+    if (_file.read((void *)&byteread, 1) != 1) {
+      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 return the offset size of the subchunk1
+      if (data == 0x64617461) {
+        return count;
+      }
+    }
+  }
+  return -1;
+}
+
 int SDWaveFile::read(void* buffer, size_t size)
 {
   uint32_t position = _file.position();
   int read = _file.read(buffer, size);
 
   if (position == 0) {
     // replace the header with 0's
-    memset(buffer, 0x00, sizeof(struct WaveFileHeader));
+    memset(buffer, 0x00, size);
   }
 
   if (read) {
@@ -206,6 +240,7 @@ void SDWaveFile::end()
 
 void SDWaveFile::readHeader()
 {
+  int headerSize = 0;
   _isValid = false;
 
   if (_headerRead) {
@@ -224,10 +259,30 @@ void SDWaveFile::readHeader()
     _file.close();
     return;
   }
-
   struct WaveFileHeader header;
 
-  if (_file.read(&header, sizeof(header)) != sizeof(header)) {
+  headerSize = sizeof(struct WaveFileHeader) - sizeof(header.subChunk2);
+  //Read the first WAV header's chunk
+  if (_file.read(&header, headerSize) != headerSize) {
+    _file.close();
+    return;
+  }
+
+  if (header.subChunk1.audioFormat != 1) {
+    _file.close();
+    return;
+  }
+
+  _headerOffset = findData(headerSize);
+  if (_headerOffset == -1) {
+    _file.close();
+    return;
+  }
+  //if findData goes fine, data label is assigned to subChunk2.id
+  header.subChunk2.id = 0x64617461;
+
+  int size = sizeof(header.subChunk2.size);
+  if (_file.read(&(header.subChunk2.size), size) != size) {
     _file.close();
     return;
   }
@@ -238,7 +293,6 @@ 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 +310,6 @@ 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(int offset);
 
 private:
   bool _headerRead;
@@ -69,6 +70,7 @@ class SDWaveFile : public SoundFile
   int _channels;
   long _frames;
   int _blockAlign;
+  int _headerOffset;
 };
 
 #endif