diff --git a/include/data_sources.h b/include/data_sources.h
index 8f19dfe..aad72ca 100644
--- a/include/data_sources.h
+++ b/include/data_sources.h
@@ -16,8 +16,9 @@ public:
 	virtual void seek(size_t position) = 0;
 	virtual size_t size() = 0;
 	virtual void close() = 0;
-	virtual void skip_id3_tag() {};
 	virtual bool usable() = 0;
+	virtual int peek(int offset) = 0;
+	void skip_id3_tag();
 };
 
 class SDDataSource : public DataSource {
@@ -32,8 +33,8 @@ public:
 	void seek(size_t position);
 	size_t size();
 	void close();
-	void skip_id3_tag();
 	bool usable();
+	int peek(int offset=0);
 };
 
 class HTTPSDataSource : public DataSource {
@@ -54,5 +55,4 @@ public:
 	void close();
 	bool usable();
 	int peek(int offset=0);
-	void skip_id3_tag();
 };
diff --git a/platformio.ini b/platformio.ini
index cc48ae3..b04eae0 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -11,21 +11,16 @@
 [platformio]
 default_envs = esp32
 
-[extra]
-lib_deps =
-	63 ; MFRC522
-	https://github.com/me-no-dev/ESPAsyncWebServer.git
-	ArduinoJSON
-	6691 ; TinyXML
-
-[env:esp32]
+[env]
 platform = espressif32
 board = esp-wrover-kit
 framework = arduino
 upload_speed = 512000
-build_flags=!./build_version.sh
-lib_deps = ${extra.lib_deps}
-upload_port = /dev/cu.SLAB_USBtoUART
+lib_deps =
+	63 ; MFRC522
+	https://github.com/me-no-dev/ESPAsyncWebServer.git
+	64 ; ArduinoJSON
+	6691 ; TinyXML
 monitor_speed = 115200
 board_build.embed_files =
 	src/webinterface/timezones.json.gz
@@ -35,10 +30,8 @@ board_build.embed_files =
 extra_scripts =
 	post:tools/post_build.py
 
+[env:esp32]
+build_flags=!./build_version.sh
+upload_port = /dev/cu.SLAB_USBtoUART
+
 [env:deploy]
-platform = espressif32
-board = esp-wrover-kit
-framework = arduino
-lib_deps = ${extra.lib_deps}
-board_build.embed_txtfiles = src/index.html
-board_build.partitions = partitions.csv
diff --git a/src/data_sources.cpp b/src/data_sources.cpp
index 0c8ff78..480f99f 100644
--- a/src/data_sources.cpp
+++ b/src/data_sources.cpp
@@ -1,5 +1,29 @@
 #include "data_sources.h"
 
+void DataSource::skip_id3_tag() {
+	if (peek(0)=='I' && peek(1)=='D' && peek(2)=='3') {
+		DEBUG("ID3 tag found\n");
+		// Skip ID3 tag marker
+		read(); read(); read();
+		// Skip ID3 tag version
+		read(); read();
+		byte tags = read();
+		bool footer_present = tags & 0x10;
+		DEBUG("ID3 footer found: %d\n", footer_present);
+		uint32_t offset = 0;
+		for (byte i=0; i<4; i++) {
+			offset <<= 7;
+			offset |= (0x7F & read());
+		}
+		offset += 10;
+		if (footer_present) offset += 10;
+		DEBUG("ID3 tag length is %d bytes.\n", offset);
+		seek(offset);
+	} else {
+		DEBUG("No ID3 tag found\n");
+	}
+}
+
 ////////////// SDDataSource //////////////
 SDDataSource::SDDataSource(String file) { _file = SD.open(file, "r"); }
 SDDataSource::~SDDataSource() { if (_file) _file.close(); }
@@ -10,33 +34,16 @@ void SDDataSource::seek(size_t position) { _file.seek(position); }
 size_t SDDataSource::size() { return _file.size(); }
 void SDDataSource::close() { _file.close(); }
 bool SDDataSource::usable() { return _file; }
-
-void SDDataSource::skip_id3_tag() {
-	uint32_t original_position = _file.position();
-	uint32_t offset = 0;
-	if (_file.read()=='I' && _file.read()=='D' && _file.read()=='3') {
-		DEBUG("ID3 tag found\n");
-		// Skip ID3 tag version
-		_file.read(); _file.read();
-		byte tags = _file.read();
-		bool footer_present = tags & 0x10;
-		DEBUG("ID3 footer found: %d\n", footer_present);
-		for (byte i=0; i<4; i++) {
-			offset <<= 7;
-			offset |= (0x7F & _file.read());
-		}
-		offset += 10;
-		if (footer_present) offset += 10;
-		DEBUG("ID3 tag length is %d bytes.\n", offset);
-		_file.seek(offset);
-	} else {
-		DEBUG("No ID3 tag found\n");
-		_file.seek(original_position);
-	}
+int SDDataSource::peek(int offset) {
+	if (offset==0) return _file.peek();
+	size_t start_position = _file.position();
+	_file.seek(start_position + offset);
+	int result = _file.peek();
+	_file.seek(start_position);
+	return result;
 }
 
 
-
 ////////////// HTTPSDataSource //////////////
 HTTPSDataSource::HTTPSDataSource(String url, uint32_t offset) {
 	_url = url;
@@ -62,27 +69,3 @@ void HTTPSDataSource::seek(size_t position) { _http->close(); delete _http; _ini
 size_t HTTPSDataSource::size() { return _http->getSize(); }
 void HTTPSDataSource::close() { _http->close(); }
 int HTTPSDataSource::peek(int offset) { return _http->peek(offset); }
-
-void HTTPSDataSource::skip_id3_tag() {
-	uint32_t offset = 0;
-	if (_http->peek(0)=='I' && _http->peek(1)=='D' && _http->peek(2)=='3') {
-		DEBUG("ID3 tag found\n");
-		// Skip ID3 tag marker
-		_http->read(); _http->read(); _http->read();
-		// Skip ID3 tag version
-		_http->read(); _http->read();
-		byte tags = _http->read();
-		bool footer_present = tags & 0x10;
-		DEBUG("ID3 footer found: %d\n", footer_present);
-		for (byte i=0; i<4; i++) {
-			offset <<= 7;
-			offset |= (0x7F & _http->read());
-		}
-		offset += 10;
-		if (footer_present) offset += 10;
-		DEBUG("ID3 tag length is %d bytes.\n", offset);
-		seek(offset);
-	} else {
-		DEBUG("No ID3 tag found\n");
-	}
-}