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 +39,11 @@ struct WaveFileHeader {
   } subChunk2;
 } __attribute__((packed));
 
+struct SubChunkHeader {
+   uint32_t id;
+   uint32_t size;
+ };
+
 SDWaveFile::SDWaveFile() : 
   SDWaveFile(NULL)
 {
@@ -129,8 +134,8 @@ long SDWaveFile::currentTime()
 
   uint32_t position = _file.position();
 
-  if (position >= sizeof(struct WaveFileHeader)) {
-    position -= sizeof(struct WaveFileHeader);
+  if (position >= _dataOffset) {
+    position -= _dataOffset;
   }
 
   return (position) / (_blockAlign * _sampleRate);
@@ -142,7 +147,7 @@ int SDWaveFile::cue(long time)
     return 1;
   }
 
-  long offset = (time * _blockAlign) - sizeof(struct WaveFileHeader);
+  long offset = (time * _blockAlign) - _dataOffset;
 
   if (offset < 0) {
     offset = 0;
@@ -180,7 +185,7 @@ int SDWaveFile::read(void* buffer, size_t size)
 
   if (position == 0) {
     // replace the header with 0's
-    memset(buffer, 0x00, sizeof(struct WaveFileHeader));
+    memset(buffer, 0x00, _dataOffset);
   }
 
   if (read) {
@@ -224,21 +229,24 @@ void SDWaveFile::readHeader()
     _file.close();
     return;
   }
-
   struct WaveFileHeader header;
+  int headerSize, dataHeaderOffset;
+  struct SubChunkHeader sch;
 
-  if (_file.read(&header, sizeof(header)) != sizeof(header)) {
+  headerSize = sizeof(struct WaveFileHeader) - sizeof(header.subChunk2);
+  if (_file.read((void *)&header, headerSize) != headerSize) {
     _file.close();
     return;
   }
-  _file.close();
 
-  _headerRead = true;
+  if (header.subChunk1.size != 16 || header.subChunk1.audioFormat != 1) {
+    _file.close();
+    return;
+  }
 
   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;
@@ -256,14 +264,25 @@ void SDWaveFile::readHeader()
     return;
   }
 
-  if (header.subChunk1.size != 16 || header.subChunk1.audioFormat != 1) {
-    // not PCM
-    return;
+  while (_file.available()) {
+    if (_file.read((void *)&(sch), sizeof(sch)) != sizeof(sch)) {
+      _file.close();
+      return;
+    }
+    sch.id = __REV(sch.id);
+    if (sch.id == 0x64617461) {
+      header.subChunk2.id = sch.id;
+      header.subChunk2.size = sch.size;
+      break;
+    } else {
+      _file.seek(_file.position() + sch.size);
+      dataHeaderOffset += 4 + sch.size;
+    }
   }
+  _dataOffset = sizeof(struct WaveFileHeader) + dataHeaderOffset;
+  _file.close();
 
-  if (header.subChunk2.id != 0x64617461) { // "data"
-    return;
-  }
+  _headerRead = true;
 
   _channels = header.subChunk1.numChannels;
   _sampleRate = header.subChunk1.sampleRate;

src/SDWaveFile.h

@@ -69,6 +69,7 @@ class SDWaveFile : public SoundFile
   int _channels;
   long _frames;
   int _blockAlign;
+  int _dataOffset;
 };
 
 #endif