sync bastp to upstream/ vanilla-music

12 files changed, 1099 insertions, 260 deletions

diff --git a/app/src/main/java/github/daneren2005/dsub/service/DownloadService.java b/app/src/main/java/github/daneren2005/dsub/service/DownloadService.java
index 67a0f36f..dbc1eacc 100644
--- a/app/src/main/java/github/daneren2005/dsub/service/DownloadService.java
+++ b/app/src/main/java/github/daneren2005/dsub/service/DownloadService.java
@@ -192,6 +192,11 @@ public class DownloadService extends Service {
 	private long subtractNextPosition = 0;
 	private int subtractPosition = 0;
 
+	/**
+	 * Reference to precreated BASTP Object
+	 */
+	private BastpUtil mBastpUtil;
+
 	@Override
 	public void onCreate() {
 		super.onCreate();
@@ -201,6 +206,7 @@ public class DownloadService extends Service {
 			public void run() {
 				Looper.prepare();
 
+				mBastpUtil = new BastpUtil();
 				mediaPlayer = new MediaPlayer();
 				mediaPlayer.setWakeMode(DownloadService.this, PowerManager.PARTIAL_WAKE_LOCK);
 
@@ -2645,7 +2651,7 @@ public class DownloadService extends Service {
 		try {
 			float adjust = 0f;
 			if (prefs.getBoolean(Constants.PREFERENCES_KEY_REPLAY_GAIN, false)) {
-				float[] rg = BastpUtil.getReplayGainValues(downloadFile.getFile().getCanonicalPath()); /* track, album */
+				BastpUtil.GainValues rg = mBastpUtil.getReplayGainValues(downloadFile.getFile().getCanonicalPath()); /* track, album */
 				boolean singleAlbum = false;
 				
 				String replayGainType = prefs.getString(Constants.PREFERENCES_KEY_REPLAY_GAIN_TYPE, "1");
@@ -2690,14 +2696,14 @@ public class DownloadService extends Service {
 				
 				
 				// If playing a single album or no track gain, use album gain
-				if((singleAlbum || rg[0] == 0) && rg[1] != 0) {
-					adjust = rg[1];
+				if((singleAlbum || rg.album == 0) && rg.track != 0) {
+					adjust = rg.album;
 				} else {
 					// Otherwise, give priority to track gain
-					adjust = rg[0];
+					adjust = rg.track;
 				}
 			
-				if (adjust == 0) {
+				if (!rg.found) {
 					/* No RG value found: decrease volume for untagged song if requested by user */
 					int untagged = Integer.parseInt(prefs.getString(Constants.PREFERENCES_KEY_REPLAY_GAIN_UNTAGGED, "0"));
 					adjust = (untagged - 150) / 10f;
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/Bastp.java b/app/src/main/java/github/daneren2005/dsub/util/tags/Bastp.java
index aa0a2e25..dd456039 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/Bastp.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/Bastp.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
+ * Copyright (C) 2017 Google Inc.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -24,10 +25,10 @@ import java.util.HashMap;
 
 
 public class Bastp {
-	
+
 	public Bastp() {
 	}
-	
+
 	public HashMap getTags(String fname) {
 		HashMap tags = new HashMap();
 		try {
@@ -44,31 +45,61 @@ public class Bastp {
 	
 	public HashMap getTags(RandomAccessFile s) {
 		HashMap tags = new HashMap();
-		byte[] file_ff = new byte[4];
+		byte[] file_ff = new byte[12];
 		
 		try {
 			s.read(file_ff);
 			String magic = new String(file_ff);
-			if(magic.equals("fLaC")) {
+			if(magic.substring(0,4).equals("fLaC")) {
 				tags = (new FlacFile()).getTags(s);
+				tags.put("type", "FLAC");
 			}
-			else if(magic.equals("OggS")) {
-				tags = (new OggFile()).getTags(s);
+			else if(magic.substring(0,4).equals("OggS")) {
+				// This may be an Opus OR an Ogg Vorbis file
+				tags = (new OpusFile()).getTags(s);
+				if (tags.size() > 0) {
+					tags.put("type", "OPUS");
+				} else {
+					tags = (new OggFile()).getTags(s);
+					tags.put("type", "OGG");
+				}
 			}
 			else if(file_ff[0] == -1 && file_ff[1] == -5) { /* aka 0xfffb in real languages */
 				tags = (new LameHeader()).getTags(s);
+				tags.put("type", "MP3/Lame");
 			}
 			else if(magic.substring(0,3).equals("ID3")) {
 				tags = (new ID3v2File()).getTags(s);
 				if(tags.containsKey("_hdrlen")) {
 					Long hlen = Long.parseLong( tags.get("_hdrlen").toString(), 10 );
 					HashMap lameInfo = (new LameHeader()).parseLameHeader(s, hlen);
-					/* add gain tags if not already present */
+					/* add tags from lame header if not already present */
 					inheritTag("REPLAYGAIN_TRACK_GAIN", lameInfo, tags);
 					inheritTag("REPLAYGAIN_ALBUM_GAIN", lameInfo, tags);
+					inheritTag("duration", lameInfo, tags);
 				}
+				tags.put("type", "MP3/ID3v2");
 			}
-			tags.put("_magic", magic);
+			else if(magic.substring(4,8).equals("ftyp") && (
+				// see http://www.ftyps.com/ for all MP4 subtypes
+				magic.substring(8,11).equals("M4A") ||  // Apple audio
+				magic.substring(8,11).equals("M4V") ||  // Apple video
+				magic.substring(8,12).equals("mp42") || // generic MP4, e.g. FAAC
+				magic.substring(8,12).equals("isom") || // generic MP4, e.g. ffmpeg
+				magic.substring(8,12).equals("dash")    // IEC 23009-1 data
+			)) {
+				tags = (new Mp4File()).getTags(s);
+				tags.put("type", "MP4");
+			}
+			else if(magic.substring(0,4).equals("MThd")) {
+				tags = (new RawFile()).getTags(s);
+				tags.put("type", "MIDI");
+			}
+			else if(file_ff[0] == -1 && (file_ff[1]&0xF0) == 0xF0) { /* aka 0xfff? */
+				tags = (new RawFile()).getTags(s);
+				tags.put("type", "ADTS");
+			}
+
 		}
 		catch (IOException e) {
 		}
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/BastpUtil.java b/app/src/main/java/github/daneren2005/dsub/util/tags/BastpUtil.java
index 7ff517fd..802aa5ad 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/BastpUtil.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/BastpUtil.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
+ * Copyright (C) 2013-2019 Adrian Ulrich <adrian@blinkenlights.ch>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -14,59 +14,115 @@
  * You should have received a copy of the GNU General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>. 
  */
- 
+
 package github.daneren2005.dsub.util.tags;
 
-import android.support.v4.util.LruCache;
+import android.util.LruCache;
+import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.Vector;
 
-public final class BastpUtil {
-	private static final RGLruCache rgCache = new RGLruCache(16);
+public class BastpUtil {
+	/**
+	 * Our global instance cache
+	 */
+	private RGLruCache rgCache;
+	/**
+	 * What we return & cache
+	 */
+	public class GainValues {
+		public float album;
+		public float track;
+		public boolean found;
+	}
+	/**
+	 * LRU cache for ReplayGain values
+	 */
+	private class RGLruCache extends LruCache<String, GainValues> {
+		public RGLruCache(int size) {
+			super(size);
+		}
+	}
+
 
-	/** Returns the ReplayGain values of 'path' as <track,album>
+	public BastpUtil() {
+		rgCache = new RGLruCache(64);
+	}
+
+	/**
+	 * Returns a GainValues object for `path'
 	 */
-	public static float[] getReplayGainValues(String path) {
-		float[] cached = rgCache.get(path);
+	public GainValues getReplayGainValues(String path) {
+		if(path == null) {
+			// path must not be null
+			path = "//null\\";
+		}
 
+		GainValues cached = rgCache.get(path);
 		if(cached == null) {
 			cached = getReplayGainValuesFromFile(path);
 			rgCache.put(path, cached);
 		}
 		return cached;
 	}
-	
-	
-	
-	/** Parse given file and return track,album replay gain values
+
+	/**
+	 *  Parse given file and return track,album replay gain values
 	 */
-	private static float[] getReplayGainValuesFromFile(String path) {
-		String[] keys = { "REPLAYGAIN_TRACK_GAIN", "REPLAYGAIN_ALBUM_GAIN" };
-		float[] adjust= { 0f                     , 0f                      };
+	private GainValues getReplayGainValuesFromFile(String path) {
 		HashMap tags  = (new Bastp()).getTags(path);
-		
-		for (int i=0; i<keys.length; i++) {
-			String curKey = keys[i];
-			if(tags.containsKey(curKey)) {
-				String rg_raw = (String)((Vector)tags.get(curKey)).get(0);
-				String rg_numonly = "";
-				float rg_float = 0f;
-				try {
-					String nums = rg_raw.replaceAll("[^0-9.-]","");
-					rg_float = Float.parseFloat(nums);
-				} catch(Exception e) {}
-				adjust[i] = rg_float;
+		GainValues gv = new GainValues();
+
+		// normal replay gain
+		if(tags.containsKey("REPLAYGAIN_TRACK_GAIN")) {
+			gv.track = getFloatFromString((String)((ArrayList)tags.get("REPLAYGAIN_TRACK_GAIN")).get(0));
+			gv.found = true;
+		}
+		if(tags.containsKey("REPLAYGAIN_ALBUM_GAIN")) {
+			gv.album = getFloatFromString((String)((ArrayList)tags.get("REPLAYGAIN_ALBUM_GAIN")).get(0));
+			gv.found = true;
+		}
+
+		// R128 replay gain
+		boolean r128 = false;
+		if(tags.containsKey("R128_BASTP_BASE_GAIN")) {
+			// This is the gain found in the opus header which automatically gets applied by the media framework.
+			// We therefore do not need to include it in our calculation, but we set the 'found' bit and reset
+			// both album and track gain information as an opus file should only ever contain r128 gain infos.
+			float base = getFloatFromString((String)((ArrayList)tags.get("R128_BASTP_BASE_GAIN")).get(0)) / 256.0f;
+			if (base != 0.0f) {
+				gv.track = 0;
+				gv.album = 0;
+				gv.found = true;
 			}
 		}
-		return adjust;
+		if(tags.containsKey("R128_TRACK_GAIN")) {
+			gv.track += getFloatFromString((String)((ArrayList)tags.get("R128_TRACK_GAIN")).get(0)) / 256.0f;
+			gv.found = true;
+			r128 = true;
+		}
+		if(tags.containsKey("R128_ALBUM_GAIN")) {
+			gv.album += getFloatFromString((String)((ArrayList)tags.get("R128_ALBUM_GAIN")).get(0)) / 256.0f;
+			gv.found = true;
+			r128 = true;
+		}
+
+		if (r128) {
+			gv.track += 5.0f;
+			gv.album += 5.0f;
+		}
+		return gv;
 	}
-	
-	/** LRU cache for ReplayGain values
+
+	/**
+	 * Parses common replayGain string values
 	 */
-	private static class RGLruCache extends LruCache<String, float[]> {
-		public RGLruCache(int size) {
-			super(size);
-		}
+	private float getFloatFromString(String rg_raw) {
+		float rg_float = 0f;
+		try {
+			String nums = rg_raw.replaceAll("[^0-9.-]","");
+			rg_float = Float.parseFloat(nums);
+		} catch(Exception e) {}
+		return rg_float;
 	}
 
 }
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/Common.java b/app/src/main/java/github/daneren2005/dsub/util/tags/Common.java
index 51344d90..c0d661f5 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/Common.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/Common.java
@@ -21,18 +21,14 @@ package github.daneren2005.dsub.util.tags;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.util.HashMap;
-import java.util.Vector;
+import java.util.ArrayList;
 
 public class Common {
-	private static final long MAX_PKT_SIZE = 524288;
-	
-	public void xdie(String reason) throws IOException {
-		throw new IOException(reason);
-	}
-	
-	/*
-	** Returns a 32bit int from given byte offset in LE
-	*/
+	private static final int MAX_COMMENT_SIZE = 512;
+
+	/**
+	 * Returns a 32bit int from given byte offset in LE
+	 */
 	public int b2le32(byte[] b, int off) {
 		int r = 0;
 		for(int i=0; i<4; i++) {
@@ -40,7 +36,17 @@ public class Common {
 		}
 		return r;
 	}
-	
+
+	/**
+	 * Same as b2le32 but reads from a RandomAccessFile instead of a buffer
+	 */
+	public int raf2le32(RandomAccessFile fh, long off) throws IOException {
+		byte[] scratch = new byte[4];
+		fh.seek(off);
+		fh.read(scratch);
+		return b2le32(scratch, 0);
+	}
+
 	public int b2be32(byte[] b, int off) {
 		return swap32(b2le32(b, off));
 	}
@@ -48,63 +54,102 @@ public class Common {
 	public int swap32(int i) {
 		return((i&0xff)<<24)+((i&0xff00)<<8)+((i&0xff0000)>>8)+((i>>24)&0xff);
 	}
-	
-	/*
-	** convert 'byte' value into unsigned int
-	*/
+
+	/**
+	 * Returns a 16bit int from given byte offset in LE
+	 */
+	public int b2le16(byte[] b, int off) {
+		return ( b2u(b[off]) | b2u(b[off+1]) << 8 );
+	}
+
+	/**
+	 * convert 'byte' value into unsigned int
+	 */
 	public int b2u(byte x) {
 		return (x & 0xFF);
 	}
 	
-	/*
-	** Printout debug message to STDOUT
-	*/
+	/**
+	 * Printout debug message to STDOUT
+	 */
 	public void debug(String s) {
 		System.out.println("DBUG "+s);
 	}
-	
-	public HashMap parse_vorbis_comment(RandomAccessFile s, long offset, long payload_len) throws IOException {
+
+	/**
+	 * Throws an exception, killing the parser
+	 */
+	public void xdie(String reason) throws IOException {
+		throw new IOException(reason);
+	}
+
+	public HashMap parse_vorbis_comment(RandomAccessFile fh, PageInfo.PageParser pp, long offset, long payload_len) throws IOException {
 		HashMap tags = new HashMap();
-		int comments   = 0;                // number of found comments 
-		int xoff       = 0;                // offset within 'scratch'
-		int can_read   = (int)(payload_len > MAX_PKT_SIZE ? MAX_PKT_SIZE : payload_len);
-		byte[] scratch = new byte[can_read];
-		
-		// seek to given position and slurp in the payload
-		s.seek(offset);
-		s.read(scratch);
-		
-		// skip vendor string in format: [LEN][VENDOR_STRING] 
-		xoff    += 4 + b2le32(scratch, xoff); // 4 = LEN = 32bit int 
-		comments = b2le32(scratch, xoff);
-		xoff    += 4;
-		
-		// debug("comments count = "+comments);
-		for(int i=0; i<comments; i++) {
-			
-			int clen = (int)b2le32(scratch, xoff);
-			xoff += 4+clen;
-			
-			if(xoff > scratch.length)
-				xdie("string out of bounds");
-			
-			String   tag_raw = new String(scratch, xoff-clen, clen);
-			String[] tag_vec = tag_raw.split("=",2);
-			String   tag_key = tag_vec[0].toUpperCase();
-			
-			addTagEntry(tags, tag_key, tag_vec[1]);
+		long last_byte = offset + payload_len;
+
+		// skip vendor string in format: [LEN][VENDOR_STRING] -> 4 = LEN = 32bit int
+		offset += 4 + raf2le32(fh, offset);
+
+		// we can now read the number of comments in this file, we will also
+		// adjust offset to point to the value after this 32bit int
+		int comments = raf2le32(fh, offset);
+		offset += 4;
+
+		for ( ; comments > 0; comments--) {
+			int comment_len = raf2le32(fh, offset);
+			offset += 4;
+			long can_read = last_byte - offset; // indicates the last byte of this page
+			int do_read  = (int)(can_read > comment_len ? comment_len : can_read); // how much data is readable in this page
+
+			if (do_read >= 3) {
+				int bsize = (do_read > MAX_COMMENT_SIZE ? MAX_COMMENT_SIZE : do_read);
+				byte[] data = new byte[bsize];
+				fh.seek(offset);
+				fh.read(data);
+				String   tag_raw = new String(data);
+				String[] tag_vec = tag_raw.split("=", 2);
+				String   tag_key = tag_vec[0].toUpperCase();
+				addTagEntry(tags, tag_key, tag_vec[1]);
+			}
+
+			// set offset to begin of next tag (OR the end of this page!)
+			offset += do_read;
+
+			// We hit the end of a stream
+			// this is most likely due to the fact that we cropped do_read to not cross
+			// the page boundary -> we must now calculate the position of the next tag
+			if (offset == last_byte) {
+				int partial_cruft = comment_len - do_read; // how many bytes we did not read
+				while(partial_cruft > 0) {
+					PageInfo pi = pp.parse_stream_page(fh, last_byte);
+					if (pi.header_len <1 || pi.payload_len < 1)
+						xdie("Data from callback doesnt make much sense");
+
+					offset += pi.header_len;             // move position behind page header
+					last_byte = offset + pi.payload_len; // and adjust the last byte to pos + payload_size
+
+					if (offset+partial_cruft < last_byte) {
+						offset += partial_cruft; // partial data ends in this block: just adjust the ofset
+						break;
+					} else {
+						// this page just contains data from the partial tag -> skip to next one
+						offset = last_byte;
+						partial_cruft -= pi.payload_len;
+					}
+				}
+			}
 		}
 		return tags;
 	}
-	
+
 	public void addTagEntry(HashMap tags, String key, String value) {
 		if(tags.containsKey(key)) {
-			((Vector)tags.get(key)).add(value); // just add to existing vector
+			((ArrayList)tags.get(key)).add(value); // just add to existing vector
 		}
 		else {
-			Vector vx = new Vector();
-			vx.add(value);
-			tags.put(key, vx);
+			ArrayList l = new ArrayList<String>();
+			l.add(value);
+			tags.put(key, l);
 		}
 	}
 	
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/FlacFile.java b/app/src/main/java/github/daneren2005/dsub/util/tags/FlacFile.java
index de3584d1..ce508d2e 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/FlacFile.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/FlacFile.java
@@ -23,7 +23,8 @@ import java.util.HashMap;
 import java.util.Enumeration;
 
 
-public class FlacFile extends Common {
+public class FlacFile extends Common implements PageInfo.PageParser {
+	private static final int FLAC_TYPE_STREAMINFO = 0; // Basic info about the stream
 	private static final int FLAC_TYPE_COMMENT = 4;   // ID of 'VorbisComment's
 	
 	public FlacFile() {
@@ -32,54 +33,87 @@ public class FlacFile extends Common {
 	public HashMap getTags(RandomAccessFile s) throws IOException {
 		int xoff  = 4;  // skip file magic
 		int retry = 64;
-		int r[];
+		boolean need_infos = true;
+		boolean need_tags = true;
+		HashMap infos = new HashMap();
 		HashMap tags = new HashMap();
-		
+
 		for(; retry > 0; retry--) {
-			r = parse_metadata_block(s, xoff);
-			
-			if(r[2] == FLAC_TYPE_COMMENT) {
-				tags = parse_vorbis_comment(s, xoff+r[0], r[1]);
-				break;
+			PageInfo pi = parse_stream_page(s, xoff);
+			if(pi.type == FLAC_TYPE_STREAMINFO) {
+				infos = parse_streaminfo_block(s, xoff+pi.header_len, pi.payload_len);
+				need_infos = false;
+			}
+			if(pi.type == FLAC_TYPE_COMMENT) {
+				tags = parse_vorbis_comment(s, this, xoff+pi.header_len, pi.payload_len);
+				need_tags = false;
 			}
-			
-			if(r[3] != 0)
+
+			if(pi.last_page == true || (need_tags == false && need_infos == false))
 				break; // eof reached
-			
+
 			// else: calculate next offset
-			xoff += r[0] + r[1];
+			xoff += pi.header_len + pi.payload_len;
+		}
+
+		// Copy duration to final hashmap if found in infoblock
+		if(infos.containsKey("duration")) {
+			tags.put("duration", infos.get("duration"));
 		}
+
 		return tags;
 	}
 	
-	/* Parses the metadata block at 'offset' and returns
-	** [header_size, payload_size, type, stop_after]
-	*/
-	private int[] parse_metadata_block(RandomAccessFile s, long offset) throws IOException {
-		int[] result   = new int[4];
+	/**
+	 * Parses the metadata block at 'offset'
+	 */
+	public PageInfo parse_stream_page(RandomAccessFile s, long offset) throws IOException {
 		byte[] mb_head = new byte[4];
 		int stop_after = 0;
 		int block_type = 0;
 		int block_size = 0;
-		
+
 		s.seek(offset);
 		
 		if( s.read(mb_head) != 4 )
 			xdie("failed to read metadata block header");
-		
+
 		block_size = b2be32(mb_head,0);                         // read whole header as 32 big endian
 		block_type = (block_size >> 24) & 127;                  // BIT 1-7 are the type
 		stop_after = (((block_size >> 24) & 128) > 0 ? 1 : 0 ); // BIT 0 indicates the last-block flag
 		block_size = (block_size & 0x00FFFFFF);                 // byte 1-7 are the size
-		
-		// debug("size="+block_size+", type="+block_type+", is_last="+stop_after);
-		
-		result[0] = 4; // hardcoded - only returned to be consistent with OGG parser
-		result[1] = block_size;
-		result[2] = block_type;
-		result[3] = stop_after;
-		
-		return result;
+
+		PageInfo pi    = new PageInfo();
+		pi.header_len  = 4; // fixed size in flac
+		pi.payload_len = block_size;
+		pi.type        = block_type;
+		pi.last_page   = (stop_after != 0);
+		return pi;
 	}
-	
+
+	/*
+	 ** Returns a hashma with parsed vorbis identification header data
+	 **/
+	private HashMap parse_streaminfo_block(RandomAccessFile s, long offset, long pl_len) throws IOException {
+		HashMap id_hash = new HashMap();
+		byte[] buff = new byte[18];
+
+		if(pl_len >= buff.length) {
+			s.seek(offset);
+			s.read(buff);
+			id_hash.put("blocksize_minimal", (b2be32(buff, 0)  >> 16));
+			id_hash.put("blocksize_maximal", (b2be32(buff, 0)  & 0x0000FFFF));
+			id_hash.put("framesize_minimal", (b2be32(buff, 4)  >> 8));
+			id_hash.put("framesize_maximal", (b2be32(buff, 7)  >> 8));
+			id_hash.put("sampling_rate",     (b2be32(buff, 10) >> 12));
+			id_hash.put("channels",          ((b2be32(buff, 10) >> 9) & 7) + 1); // 3 bits
+			id_hash.put("num_samples",       b2be32(buff, 14)); // fixme: this is actually 36 bit: the 4 hi bits are discarded due to java
+			if((Integer)id_hash.get("sampling_rate") > 0) {
+				int duration = (Integer)id_hash.get("num_samples") / (Integer)id_hash.get("sampling_rate");
+				id_hash.put("duration", (int)duration);
+			}
+		}
+		return id_hash;
+	}
+
 }
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/ID3v2File.java b/app/src/main/java/github/daneren2005/dsub/util/tags/ID3v2File.java
index 69668475..4fb7418d 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/ID3v2File.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/ID3v2File.java
@@ -1,5 +1,6 @@
 /*
- * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
+ * Copyright (C) 2013-2016 Adrian Ulrich <adrian@blinkenlights.ch>
+ * Copyright (C) 2017-2018 Google Inc.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -12,7 +13,7 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>. 
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 package github.daneren2005.dsub.util.tags;
@@ -21,160 +22,246 @@ import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.Locale;
+import java.util.Enumeration;
+
 
 
 public class ID3v2File extends Common {
-	private static int ID3_ENC_LATIN   = 0x00;
-	private static int ID3_ENC_UTF16LE = 0x01;
-	private static int ID3_ENC_UTF16BE = 0x02;
-	private static int ID3_ENC_UTF8    = 0x03;
-	
+	private static final int ID3_ENC_LATIN   = 0x00;
+	private static final int ID3_ENC_UTF16   = 0x01;
+	private static final int ID3_ENC_UTF16BE = 0x02;
+	private static final int ID3_ENC_UTF8    = 0x03;
+	private static final HashMap<String, String> sOggNames;
+	static {
+		// ID3v2.3 -> ogg mapping
+		sOggNames = new HashMap<String, String>();
+		sOggNames.put("TIT2", "TITLE");
+		sOggNames.put("TALB", "ALBUM");
+		sOggNames.put("TPE1", "ARTIST");
+		sOggNames.put("TPE2", "ALBUMARTIST");
+		sOggNames.put("TYER", "YEAR");
+		sOggNames.put("TPOS", "DISCNUMBER");
+		sOggNames.put("TRCK", "TRACKNUMBER");
+		sOggNames.put("TCON", "GENRE");
+		sOggNames.put("TCOM", "COMPOSER");
+		// ID3v2.2 3-character names
+		sOggNames.put("TT2", "TITLE");
+		sOggNames.put("TAL", "ALBUM");
+		sOggNames.put("TP1", "ARTIST");
+		sOggNames.put("TP2", "ALBUMARTIST");
+		sOggNames.put("TYE", "YEAR");
+		sOggNames.put("TRK", "TRACKNUMBER");
+		sOggNames.put("TCO", "GENRE");
+		sOggNames.put("TCM", "COMPOSER");
+	}
+
+	// Holds a key-value pair
+	private class TagItem {
+		String key;
+		String value;
+		public TagItem(String key, String value) {
+			this.key = key;
+			this.value = value;
+		}
+	}
+
 	public ID3v2File() {
 	}
-	
+
 	public HashMap getTags(RandomAccessFile s) throws IOException {
 		HashMap tags = new HashMap();
-		
+
 		final int v2hdr_len = 10;
 		byte[] v2hdr = new byte[v2hdr_len];
-		
+
 		// read the whole 10 byte header into memory
 		s.seek(0);
 		s.read(v2hdr);
-		
-		int id3v   = ((b2be32(v2hdr,0))) & 0xFF;   // swapped ID3\04 -> ver. ist the first byte
-		int v3len  = ((b2be32(v2hdr,6)));          // total size EXCLUDING the this 10 byte header
-		v3len      = ((v3len & 0x7f000000) >> 3) | // for some funky reason, this is encoded as 7*4 bits
-		             ((v3len & 0x007f0000) >> 2) |
-		             ((v3len & 0x00007f00) >> 1) |
-		             ((v3len & 0x0000007f) >> 0) ;
-		
-		// debug(">> tag version ID3v2."+id3v);
-		// debug(">> LEN= "+v3len+" // "+v3len);
-		
+
+		int v3major = (b2be32(v2hdr, 0)) & 0xFF;   // swapped ID3\04 -> ver. ist the first byte
+		int v3minor = (b2be32(v2hdr, 1)) & 0xFF;   // minor version, not used by us.
+		int v3flags = (b2be32(v2hdr, 2)) & 0xFF;   // flags such as extended headers.
+		int v3len   = (b2be32(v2hdr, 6));          // total size EXCLUDING the this 10 byte header
+		v3len       = unsyncsafe(v3len);
+
+		// In 2.4, bit #6 indicates whether or not this file has an extended header
+		boolean flag_ext_hdr = v3major >= 4 && (v3flags & (1 << 6)) != 0;
+
+		if (flag_ext_hdr) {
+			// The extended header is at least 6 bytes:
+			// * 4 byts of size
+			// * 1 byte numflags
+			// * 1 byte extended flags
+			byte[] exthdr = new byte[6];
+			long pos = s.getFilePointer();
+			s.read(exthdr);
+
+			// we got the length, so we can seek to the header end.
+			int extlen = (b2be32(exthdr, 0));
+			s.seek(pos + extlen);
+		}
+
 		// we should already be at the first frame
 		// so we can start the parsing right now
-		tags = parse_v3_frames(s, v3len);
+		tags = parse_v3_frames(s, v3len, v3major);
 		tags.put("_hdrlen", v3len+v2hdr_len);
 		return tags;
 	}
-	
+
+	/*
+	**  converts syncsafe integer to Java integer
+	*/
+	private int unsyncsafe(int x) {
+		x     = ((x & 0x7f000000) >> 3) |
+				((x & 0x007f0000) >> 2) |
+				((x & 0x00007f00) >> 1) |
+				((x & 0x0000007f) >> 0) ;
+		return x;
+	}
+
+	/**
+	 * Calculates the frame length baased on the frame size and the
+	 */
+	private int calculateFrameLength(byte[] frame, int offset, int v3major) {
+		// ID3v2 (aka ID3v2.2) had a 3-byte unencoded length field.
+		if (v3major < 3) {
+			return (frame[offset] << 16) + (frame[offset+1] << 8) + frame[offset+2];
+		}
+		int rawlen = b2be32(frame, offset);
+		// Encoders prior ID3v2.4 did not encode the frame length
+		if (v3major < 4) {
+			return rawlen;
+		}
+		return unsyncsafe(rawlen);
+	}
+
 	/* Parses all ID3v2 frames at the current position up until payload_len
 	** bytes were read
 	*/
-	public HashMap parse_v3_frames(RandomAccessFile s, long payload_len) throws IOException {
+	public HashMap parse_v3_frames(RandomAccessFile s, long payload_len, int v3major) throws IOException {
 		HashMap tags = new HashMap();
-		byte[] frame   = new byte[10]; // a frame header is always 10 bytes
-		long bread     = 0;            // total amount of read bytes
-		
+		// ID3v2 (aka ID3v2.2) had a 6-byte header of a 3-byte name and a 3-byte length.
+		// ID3v2.3 increased the header size to 10 bytes, with a 4-byte name and a 4-byte length
+		int namelen = (v3major >= 3 ? 4 : 3);
+		int headerlen = (v3major >= 3 ? 10 : 6);
+		byte[] frame   = new byte[headerlen];
+		long bread     = 0;                      // total amount of read bytes
+
 		while(bread < payload_len) {
 			bread += s.read(frame);
-			String framename = new String(frame, 0, 4);
-			int slen = b2be32(frame, 4);
-			
+			String framename = new String(frame, 0, namelen);
+			int slen = calculateFrameLength(frame, namelen, v3major);
 			/* Abort on silly sizes */
-			if(slen < 1 || slen > 524288)
+			long bytesRemaining = payload_len - bread;
+			if(slen < 1 || slen > bytesRemaining)
 				break;
-			
+
 			byte[] xpl = new byte[slen];
 			bread += s.read(xpl);
 
 			if(framename.substring(0,1).equals("T")) {
-				String[] nmzInfo = normalizeTaginfo(framename, xpl);
-
-				for(int i = 0; i < nmzInfo.length; i += 2) {
-					String oggKey = nmzInfo[i];
-					String decPld = nmzInfo[i + 1];
-
-					if (oggKey.length() > 0 && !tags.containsKey(oggKey)) {
-						addTagEntry(tags, oggKey, decPld);
+				TagItem nti = normalizeTaginfo(framename, xpl);
+				if (nti.key.length() > 0) {
+					for (TagItem ti : splitTagPayload(nti)) {
+						addTagEntry(tags, ti.key, ti.value);
 					}
 				}
 			}
 			else if(framename.equals("RVA2")) {
 				//
 			}
-			
+
 		}
 		return tags;
 	}
-	
+
+	/* Split null-separated tags into individual elements */
+	private ArrayList<TagItem> splitTagPayload(TagItem in) {
+		ArrayList res = new ArrayList<TagItem>();
+		int i = 0;
+
+		if (sOggNames.containsValue(in.key)) {
+			// Only try to split if there are more than two chars and the string does NOT look UTF16 encoded.
+			if (in.value.length() >= 2 && in.value.charAt(0) != 0 && in.value.charAt(1) != 0) {
+				for (String item : in.value.split("\0")) {
+					if (item.length() > 0) { // do not add empty items, avoids thrashing if the string is zero padded.
+						res.add(new TagItem(in.key, item));
+					}
+					i++;
+				}
+			}
+		}
+
+		if (i == 0) {
+			res.add(in);
+		}
+		return res;
+	}
+
 	/* Converts ID3v2 sillyframes to OggNames */
-	private String[] normalizeTaginfo(String k, byte[] v) {
-		String[] rv = new String[] {"",""};
-		HashMap lu = new HashMap<String, String>();
-		lu.put("TIT2", "TITLE");
-		lu.put("TALB", "ALBUM");
-		lu.put("TPE1", "ARTIST");
-		
-		if(lu.containsKey(k)) {
+	private TagItem normalizeTaginfo(String k, byte[] v) {
+		TagItem ti = new TagItem("", "");
+		if(sOggNames.containsKey(k)) {
 			/* A normal, known key: translate into Ogg-Frame name */
-			rv[0] = (String)lu.get(k);
-			rv[1] = getDecodedString(v);
+			ti.key = (String)sOggNames.get(k);
+			ti.value = getDecodedString(v);
 		}
 		else if(k.equals("TXXX")) {
 			/* A freestyle field, ieks! */
 			String txData[] = getDecodedString(v).split(Character.toString('\0'), 2);
 			/* Check if we got replaygain info in key\0value style */
-			if(txData.length == 2) {
-				if(txData[0].matches("^(?i)REPLAYGAIN_(ALBUM|TRACK)_GAIN$")) {
-					rv[0] = txData[0].toUpperCase(); /* some tagwriters use lowercase for this */
-					rv[1] = txData[1];
-				} else {
-					// Check for replaygain tags just thrown randomly in field
-					int nextStartIndex = 1;
-					int startName = txData[1].toLowerCase(Locale.US).indexOf("replaygain_");
-					ArrayList<String> parts = new ArrayList<String>();
-					while(startName != -1) {
-						int endName = txData[1].indexOf((char) 0, startName);
-						if(endName != -1) {
-							parts.add(txData[1].substring(startName, endName).toUpperCase());
-							int endValue = txData[1].indexOf((char) 0, endName + 1);
-							if(endValue != -1) {
-								parts.add(txData[1].substring(endName + 1, endValue));
-								nextStartIndex = endValue + 1;
-							} else {
-								break;
-							}
-						} else {
-							break;
-						}
-
-						startName = txData[1].toLowerCase(Locale.US).indexOf("replaygain_", nextStartIndex);
-					}
-
-					if(parts.size() > 0) {
-						rv = new String[parts.size()];
-						rv = parts.toArray(rv);
-					}
-				}
+			if(txData.length == 2 && txData[0].matches("^(?i)REPLAYGAIN_(ALBUM|TRACK)_GAIN$")) {
+				ti.key = txData[0].toUpperCase(); /* some tagwriters use lowercase for this */
+				ti.value = txData[1];
 			}
 		}
-		
-		return rv;
+
+		return ti;
 	}
-	
+
 	/* Converts a raw byte-stream text into a java String */
 	private String getDecodedString(byte[] raw) {
 		int encid = raw[0] & 0xFF;
-		int len   = raw.length;
-		String v  = "";
+		int skip  = 1;
+		String cs = "ISO-8859-1";
+		String rv  = "";
 		try {
-			if(encid == ID3_ENC_LATIN) {
-				v = new String(raw, 1, len-1, "ISO-8859-1");
-			}
-			else if (encid == ID3_ENC_UTF8) {
-				v = new String(raw, 1, len-1, "UTF-8");
-			}
-			else if (encid == ID3_ENC_UTF16LE) {
-				v = new String(raw, 3, len-3, "UTF-16LE");
+			switch (encid) {
+				case ID3_ENC_UTF8:
+					cs = "UTF-8";
+					break;
+				case ID3_ENC_UTF16BE:
+					cs = "UTF-16BE";
+					skip = 3;
+					break;
+				case ID3_ENC_UTF16:
+					cs = "UTF-16";
+					if (raw.length > 4) {
+						if ((raw[1]&0xFF) == 0xFE && (raw[2]&0XFF) == 0xFF && (raw[3]&0xFF) == 0x00 && (raw[4]&0xFF) == 0x00) {
+							// buggy tag written by lame?!
+							raw[3] = raw[2];
+							raw[4] = raw[1];
+							skip = 3;
+						} else if((raw[1]&0xFF) == 0xFF && (raw[2]&0XFF) == 0x00 && (raw[3]&0xFF) == 0xFE) {
+							// ?!, but seen in the wild
+							raw[2] = raw[1];
+							skip = 2;
+						}
+					}
+					break;
+				case ID3_ENC_LATIN:
+				default:
+					// uses defaults
 			}
-			else if (encid == ID3_ENC_UTF16BE) {
-				v = new String(raw, 3, len-3, "UTF-16BE");
+
+			rv = new String(raw, skip, raw.length-skip, cs);
+
+			if (rv.length() > 0 && rv.substring(rv.length()-1).equals("\0")) {
+				// SOME tag writers seem to null terminate strings, some don't...
+				rv = rv.substring(0, rv.length()-1);
 			}
 		} catch(Exception e) {}
-		return v;
+		return rv;
 	}
-	
+
 }
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/LameHeader.java b/app/src/main/java/github/daneren2005/dsub/util/tags/LameHeader.java
index 720ee87f..691c7279 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/LameHeader.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/LameHeader.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
+ * Copyright (C) 2017 Google Inc.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -19,28 +20,122 @@ package github.daneren2005.dsub.util.tags;
 
 import java.io.IOException;
 import java.io.RandomAccessFile;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Enumeration;
 
 
 public class LameHeader extends Common {
-	
+
+	// Sampling rate version -> field mapping
+	private static int[][] sampleRates = {
+		{ 11025, 12000,  8000 }, // MPEG2.5 (idx = 0)
+		{     0,     0,     0 }, // reserved (idx = 1)
+		{ 22050, 24000, 16000 }, // MPEG2 (idx = 2)
+		{ 44100, 48000, 32000 }, // MPEG1 (idx = 3)
+	};
+
+	// SamplesPerFrame layer -> version mapping
+	private static int[][] samplesPerFrame = {
+		// reserved, layer3, layer2, layer1
+		{  0,        576,   1152,  384 }, // MPEG2.5
+		{  0,          0,      0,    0 }, // RESERVED
+		{  0,        576,   1152,  384 }, // MPEG2
+		{  0,       1152,   1152,  384 }, // MPEG1
+	};
+
+
 	public LameHeader() {
 	}
 	
 	public HashMap getTags(RandomAccessFile s) throws IOException {
-		return parseLameHeader(s, 0);
+		HashMap rgain = parseLameHeader(s, 0);
+		HashMap tags = parseV1Header(s, s.length()-128);
+
+		// Add replay gain info to returned object if available
+		for (String k : Arrays.asList("REPLAYGAIN_TRACK_GAIN", "REPLAYGAIN_ALBUM_GAIN")) {
+			if (rgain.containsKey(k))
+				tags.put(k, rgain.get(k));
+		}
+
+		return tags;
 	}
-	
+
+	/**
+	 * Attempts to parse ID3v1(.1) information from given RandomAccessFile
+	 *
+	 * @param s the seekable RandomAccessFile
+	 * @param offset position of the ID3v1 tag
+	 */
+	private HashMap parseV1Header(RandomAccessFile s, long offset) throws IOException {
+		HashMap tags = new HashMap();
+		byte[] tag  = new byte[3];
+		byte[] year = new byte[4];
+		byte[] str  = new byte[30];
+
+		s.seek(offset);
+		s.read(tag);
+
+		if("TAG".equals(new String(tag))) {
+			for (String name : Arrays.asList("TITLE", "ARTIST", "ALBUM")) {
+				s.read(str);
+				String value = new String(str, "ISO-8859-1").trim();
+				if (value.length() > 0)
+					addTagEntry(tags, name, value);
+			}
+
+			// year is a string for whatever reason...
+			s.read(year);
+			String y = new String(year).trim();
+			if (y.length() > 0)
+				addTagEntry(tags, "YEAR", y);
+
+			s.skipBytes(28); // skip comment field
+			s.read(tag);
+
+			if (tag[0] == 0 && tag[1] != 0) // tag[0] == 0 -> is id3v1.1 compatible
+				addTagEntry(tags, "TRACKNUMBER", String.format("%d", tag[1]));
+
+			if (tag[2] != 0)
+				addTagEntry(tags, "GENRE", String.format("%d", tag[2]));
+		}
+
+
+		return tags;
+	}
+
 	public HashMap parseLameHeader(RandomAccessFile s, long offset) throws IOException {
 		HashMap tags = new HashMap();
-		byte[] chunk = new byte[4];
+		byte[] chunk = new byte[12];
 		
 		s.seek(offset + 0x24);
 		s.read(chunk);
 		
-		String lameMark = new String(chunk, 0, chunk.length, "ISO-8859-1");
-		
+		String lameMark = new String(chunk, 0, 4, "ISO-8859-1");
+		int flags = b2u(chunk[7]);
+
+		if((flags & 0x01) !=0 ) { // header indicates that totalFrames field is present
+			int total_frames = b2be32(chunk, 8);
+			s.seek(offset);
+			s.read(chunk);
+
+			int mpeg_hdr = b2be32(chunk, 0);
+			int srate_idx = (mpeg_hdr >> 10) & 3; // sampling rate index at bit 10-11
+			int layer_idx = (mpeg_hdr >> 17) & 3; // layer index value bit 17-18
+			int ver_idx   = (mpeg_hdr >> 19) & 3; // version index value bit 19-20
+
+			// Try to calculate song duration if all indexes are sane
+			if (ver_idx < sampleRates.length && srate_idx < sampleRates[ver_idx].length && layer_idx < samplesPerFrame[ver_idx].length) {
+				int sample_rate = sampleRates[ver_idx][srate_idx];
+				int sample_pfr  = samplesPerFrame[ver_idx][layer_idx];
+				if (sample_rate > 0 && sample_pfr > 0) {
+					double duration = ((double)sample_pfr / (double)sample_rate) * total_frames;
+					tags.put("duration", (int)duration);
+				}
+			}
+
+		}
+
 		if(lameMark.equals("Info") || lameMark.equals("Xing")) {
 			s.seek(offset+0xAB);
 			s.read(chunk);
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/Mp4File.java b/app/src/main/java/github/daneren2005/dsub/util/tags/Mp4File.java
new file mode 100644
index 00000000..db00bf6a
--- /dev/null
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/Mp4File.java
@@ -0,0 +1,254 @@
+/*
+ * Copyright (C) 2016 Ian Harmon
+ * Copyright (C) 2017 Google Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package github.daneren2005.dsub.util.tags;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Stack;
+
+/*
+* Helper class for tracking the traversal of the atom tree
+*/
+class Atom {
+	String name;
+	long start;
+	int length;
+	
+	public Atom(String name, long start, int length) {
+		this.name = name;
+		this.start = start;
+		this.length = length;
+	}
+}
+
+/*
+* MP4 tag parser
+*/
+public class Mp4File extends Common {
+
+	// only these tags are returned. others may be parsed, but discarded.
+	final static List<String> ALLOWED_TAGS = Arrays.asList(
+		"replaygain_track_gain",
+		"replaygain_album_gain",
+		"title",
+		"album",
+		"artist",
+		"albumartist",
+		"composer",
+		"genre",
+		"year",
+		"tracknumber",
+		"discnumber"
+	);
+
+	// mapping between atom <-> vorbis tags
+	final static HashMap<String, String> ATOM_TAGS;
+	static {
+		ATOM_TAGS = new HashMap<String, String>();
+		ATOM_TAGS.put("�nam", "title");
+		ATOM_TAGS.put("�alb", "album");
+		ATOM_TAGS.put("�ART", "artist");
+		ATOM_TAGS.put("aART", "albumartist");
+		ATOM_TAGS.put("�wrt", "composer");
+		ATOM_TAGS.put("�gen", "genre");
+		ATOM_TAGS.put("�day", "year");
+		ATOM_TAGS.put("trkn", "tracknumber");
+		ATOM_TAGS.put("disk", "discnumber");
+	}
+
+	// These tags are 32bit integers, not strings.
+	final static List<String> BINARY_TAGS = Arrays.asList(
+		"tracknumber",
+		"discnumber"
+	);
+
+	// maximum size for tag names or values
+	final static int MAX_BUFFER_SIZE = 512;
+	// only used when developing
+	final static boolean PRINT_DEBUG = false;
+
+	// When processing atoms, we first read the atom length (4 bytes),
+	// and then the atom name (also 4 bytes). This value should not be changed.
+	final static int ATOM_HEADER_SIZE = 8;
+	
+	/*
+	* Traverses the atom structure of an MP4 file and returns as soon as tags
+	* are parsed
+	*/
+	public HashMap getTags(RandomAccessFile s) throws IOException {
+		HashMap tags = new HashMap();
+		if (PRINT_DEBUG) { System.out.println(); }
+		try {
+
+			// maintain a trail of breadcrumbs to know what part of the file we're in,
+			// so e.g. that we only parse [name] atoms that are part of a tag
+			Stack<Atom> path = new Stack<Atom>();
+
+			s.seek(0);
+			int atomSize;
+			byte[] atomNameRaw = new byte[4];
+			String atomName;
+			String tagName = null;
+
+			// begin traversing the file
+			// file structure info from http://atomicparsley.sourceforge.net/mpeg-4files.html
+			while (s.getFilePointer() < s.length()) {
+
+				// if we've read/skipped past the end of atoms, remove them from the path stack
+				while (!path.empty() && s.getFilePointer() >= (path.peek().start + path.peek().length)) {
+					// if we've finished the tag atom [ilst], we can stop parsing.
+					// when tags are read successfully, this should be the exit point for the parser.
+					if (path.peek().name.equals("ilst")) {
+						if (PRINT_DEBUG) { System.out.println(); }
+						return tags;
+					}
+					path.pop();
+				}
+
+				// read a new atom's details
+				atomSize = s.readInt();
+
+				// return if we're unable to parse an atom size
+				// (e.g. previous atoms were parsed incorrectly and the
+				// file pointer is misaligned)
+				if (atomSize <= 0) { return tags; }
+
+				s.read(atomNameRaw);
+				atomName = new String(atomNameRaw);
+
+				// determine if we're currently decending through the hierarchy
+				// to a tag atom
+				boolean approachingTagAtom = false;
+				boolean onMetaAtom = false;
+				boolean onTagAtom = false;
+				String fourAtom = null;
+				// compare everything in the current path hierarchy and the new atom as well
+				// this is a bit repetitive as-is, but shouldn't be noticeable
+				for (int i = 0; i <= path.size(); i++) {
+					String thisAtomName = (i < path.size()) ? path.get(i).name : atomName;
+					if ((i == 0 && thisAtomName.equals("moov"))         ||
+						(i == 1 && thisAtomName.equals("udta"))         ||
+						(i == 2 && thisAtomName.equals("meta"))         ||
+						(i == 3 && thisAtomName.equals("ilst"))         ||
+						(i == 4 && thisAtomName.equals("----"))         ||
+						(i == 4 && ATOM_TAGS.containsKey(thisAtomName)) ||
+						(i == 5 && (thisAtomName.equals("name")         || thisAtomName.equals("data")))
+					) {
+						approachingTagAtom = true;
+						// if we're at the end of the current hierarchy, mark if it's the [meta] or a tag atom.
+						if (i == path.size()) {
+							onMetaAtom = thisAtomName.equals("meta");
+							onTagAtom = (thisAtomName.equals("name") || thisAtomName.equals("data"));
+						}
+						// depth is 4 and this is a known atom: rembemer this!
+						if (i == 4 && ATOM_TAGS.containsKey(thisAtomName)) {
+							fourAtom = ATOM_TAGS.get(thisAtomName);
+						}
+					}
+					// quit as soon as we know we're not on the road to a tag atom
+					else {
+						approachingTagAtom = false;
+						break;
+					}
+				}
+
+				// add the new atom to the path hierarchy
+				path.push(new Atom(atomName, s.getFilePointer()-ATOM_HEADER_SIZE, atomSize));
+				if (PRINT_DEBUG) { printDebugAtomPath(s, path, atomName, atomSize); }
+
+				// skip all non-pertinent atoms
+				if (!approachingTagAtom) { s.skipBytes(atomSize-ATOM_HEADER_SIZE); }
+				// dive into tag-related ones
+				else {
+					// the meta atom has an extra 4 bytes that need to be skipped
+					if (onMetaAtom) { s.skipBytes(4); }
+
+					// read tag contents when there
+					if (onTagAtom) {
+						// get a tag name
+						if (atomName.equals("name")) {
+							// skip null bytes
+							s.skipBytes(4);
+							tagName = new String(readIntoBuffer(s, atomSize-(ATOM_HEADER_SIZE+4)));
+						}
+
+						// get a tag value
+						else if (atomName.equals("data")) {
+							// skip flags/null bytes
+							s.skipBytes(8);
+
+							// use the 'fourAtom' value if we did not have a tag name
+							tagName = (tagName == null ? fourAtom : tagName);
+							// read the tag
+							byte[] tagBuffer = readIntoBuffer(s, atomSize-(ATOM_HEADER_SIZE+8));
+
+							if (ALLOWED_TAGS.contains(tagName))
+							{
+								String tagValue = (BINARY_TAGS.contains(tagName) ? String.format("%d", b2be32(tagBuffer, 0)) : new String(tagBuffer, "UTF-8"));
+								if (PRINT_DEBUG) {
+									System.out.println(String.format("parsed tag '%s': '%s'\n", tagName, tagValue));
+								}
+								addTagEntry(tags, tagName.toUpperCase(), tagValue);
+							}
+							// This is the end of this tree, make sure that we don't re-use tagName in any other tree
+							tagName = null;
+						}
+					}
+				}
+			}
+			// End of while loop, the file has been completely read through.
+			// The parser should only return here if the tags atom [ilst] was missing.
+			return tags;
+		}
+		// if anything goes wrong, just return whatever we already have
+		catch (Exception e) {
+			return tags;
+		}
+	}
+
+	/*
+	* Reads bytes from an atom up to the buffer size limit, currently 512B
+	*/
+	private byte[] readIntoBuffer(RandomAccessFile s, int dataSize) throws IOException {
+		// read tag up to buffer limit
+		int bufferSize = Math.min(dataSize, MAX_BUFFER_SIZE);
+		byte[] buffer = new byte[bufferSize];
+		s.read(buffer, 0, buffer.length);
+		if (dataSize > bufferSize) {
+			s.skipBytes(dataSize - bufferSize);
+		}
+		return buffer;
+	}
+
+	/*
+	* Can be used when traversing the atom hierarchy to print the tree of atoms
+	*/
+	private void printDebugAtomPath(RandomAccessFile s, Stack<Atom> path,
+		String atomName, int atomSize) throws IOException
+	{
+		String treeLines = "";
+		for (int i = 0; i < path.size(); i++) { treeLines += ". "; }
+		long atomStart = s.getFilePointer()-ATOM_HEADER_SIZE;
+		System.out.println(String.format("%-22s %8d to %8d, length %8d",
+			(treeLines + "[" + atomName + "]"), atomStart, (atomStart+atomSize), atomSize));
+	}
+}
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/OggFile.java b/app/src/main/java/github/daneren2005/dsub/util/tags/OggFile.java
index d0b31671..0383c68a 100644
--- a/app/src/main/java/github/daneren2005/dsub/util/tags/OggFile.java
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/OggFile.java
@@ -23,10 +23,11 @@ import java.io.RandomAccessFile;
 import java.util.HashMap;
 
 
-public class OggFile extends Common {
+public class OggFile extends Common implements PageInfo.PageParser {
 
-	private static final int OGG_PAGE_SIZE    = 27;  // Static size of an OGG Page
-	private static final int OGG_TYPE_COMMENT = 3;   // ID of 'VorbisComment's
+	private static final int OGG_PAGE_SIZE           = 27;  // Static size of an OGG Page
+	private static final int OGG_TYPE_IDENTIFICATION = 1;   // Identification header
+	private static final int OGG_TYPE_COMMENT        = 3;   // ID of 'VorbisComment's
 	
 	public OggFile() {
 	}
@@ -34,24 +35,46 @@ public class OggFile extends Common {
 	public HashMap getTags(RandomAccessFile s) throws IOException {
 		long offset = 0;
 		int  retry  = 64;
+		boolean need_tags = true;
+		boolean need_id = true;
+
 		HashMap tags = new HashMap();
+		HashMap identification = new HashMap();
 		
 		for( ; retry > 0 ; retry-- ) {
-			long res[] = parse_ogg_page(s, offset);
-			if(res[2] == OGG_TYPE_COMMENT) {
-				tags = parse_ogg_vorbis_comment(s, offset+res[0], res[1]);
+			PageInfo pi = parse_stream_page(s, offset);
+			if(pi.type == OGG_TYPE_IDENTIFICATION) {
+				identification = parse_ogg_vorbis_identification(s, offset+pi.header_len, pi.payload_len);
+				need_id = false;
+			} else if(pi.type == OGG_TYPE_COMMENT) {
+				tags = parse_ogg_vorbis_comment(s, offset+pi.header_len, pi.payload_len);
+				need_tags = false;
+			}
+			offset += pi.header_len + pi.payload_len;
+			if (need_tags == false && need_id == false) {
 				break;
 			}
-			offset += res[0] + res[1];
 		}
+
+		// Calculate duration in seconds
+		// Note that this calculation is WRONG: We would have to get the last
+		// packet to calculate the real length - but this is goot enough.
+		if (identification.containsKey("bitrate_nominal")) {
+			int br_nom = (Integer)identification.get("bitrate_nominal") / 8;
+			long file_length = s.length();
+			if (file_length > 0 && br_nom > 0) {
+				tags.put("duration", (int)(file_length/br_nom));
+			}
+		}
+
 		return tags;
 	}
 	
 	
-	/* Parses the ogg page at offset 'offset' and returns
-	** [header_size, payload_size, type]
-	*/
-	private long[] parse_ogg_page(RandomAccessFile s, long offset) throws IOException {
+	/**
+	 * Parses the ogg page at offset 'offset'
+	 */
+	public PageInfo parse_stream_page(RandomAccessFile s, long offset) throws IOException {
 		long[] result   = new long[3];               // [header_size, payload_size]
 		byte[] p_header = new byte[OGG_PAGE_SIZE];   // buffer for the page header 
 		byte[] scratch;
@@ -78,18 +101,18 @@ public class OggFile extends Common {
 				psize += b2u(scratch[i]); 
 			}
 		}
-		
-		// populate result array
-		result[0] = (s.getFilePointer() - offset);
-		result[1] = psize;
-		result[2] = -1;
-		
+
+		PageInfo pi    = new PageInfo();
+		pi.header_len  = (s.getFilePointer() - offset);
+		pi.payload_len = psize;
+		pi.type        = -1;
+
 		/* next byte is most likely the type -> pre-read */
 		if(psize >= 1 && s.read(p_header, 0, 1) == 1) {
-			result[2] = b2u(p_header[0]);
+			pi.type = b2u(p_header[0]);
 		}
-		
-		return result;
+
+		return pi;
 	}
 	
 	/* In 'vorbiscomment' field is prefixed with \3vorbis in OGG files
@@ -108,7 +131,37 @@ public class OggFile extends Common {
 		if( (new String(pfx, 0, pfx_len)).equals("\3vorbis") == false )
 			xdie("Damaged packet found!");
 		
-		return parse_vorbis_comment(s, offset+pfx_len, pl_len-pfx_len);
+		return parse_vorbis_comment(s, this, offset+pfx_len, pl_len-pfx_len);
 	}
-	
+
+	/*
+	 ** Returns a hashma with parsed vorbis identification header data
+	 **/
+	private HashMap parse_ogg_vorbis_identification(RandomAccessFile s, long offset, long pl_len) throws IOException {
+		/* Structure:
+		 * 7 bytes of \1vorbis
+		 * 4 bytes version
+		 * 1 byte channels
+		 * 4 bytes sampling rate
+		 * 4 bytes bitrate max
+		 * 4 bytes bitrate nominal
+		 * 4 bytes bitrate min
+		 **/
+		HashMap id_hash = new HashMap();
+		byte[] buff = new byte[28];
+
+		if(pl_len >= buff.length) {
+			s.seek(offset);
+			s.read(buff);
+			id_hash.put("version"         , b2le32(buff, 7));
+			id_hash.put("channels"        , b2u(buff[11]));
+			id_hash.put("sampling_rate"   , b2le32(buff, 12));
+			id_hash.put("bitrate_minimal" , b2le32(buff, 16));
+			id_hash.put("bitrate_nominal" , b2le32(buff, 20));
+			id_hash.put("bitrate_maximal" , b2le32(buff, 24));
+		}
+
+		return id_hash;
+	}
+
 };
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/OpusFile.java b/app/src/main/java/github/daneren2005/dsub/util/tags/OpusFile.java
new file mode 100644
index 00000000..38b402bb
--- /dev/null
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/OpusFile.java
@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2015 Adrian Ulrich <adrian@blinkenlights.ch>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>. 
+ */
+package github.daneren2005.dsub.util.tags;
+
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.HashMap;
+
+
+public class OpusFile extends OggFile {
+	// A list of tags we are going to ignore in the OpusTags section
+	public static final String[] FORBIDDEN_TAGS = {"REPLAYGAIN_TRACK_GAIN", "REPLAYGAIN_TRACK_PEAK", "REPLAYGAIN_ALBUM_GAIN", "REPLAYGAIN_ALBUM_PEAK"};
+
+	public OpusFile() {
+	}
+
+	public HashMap getTags(RandomAccessFile s) throws IOException {
+
+		// The opus specification is very strict: The first packet MUST
+		// contain the OpusHeader while the 2nd MUST contain the
+		// OggHeader payload: https://wiki.xiph.org/OggOpus
+		long pos = 0;
+		PageInfo pi =  parse_stream_page(s, pos);
+
+		HashMap tags = new HashMap();
+		HashMap opus_head = parse_opus_head(s, pos+pi.header_len, pi.payload_len);
+		pos += pi.header_len+pi.payload_len;
+
+		// Check if we parsed a version number and ensure it doesn't have any
+		// of the upper 4 bits set (eg: <= 15)
+		if(opus_head.containsKey("version") && (Integer)opus_head.get("version") <= 0xF) {
+			// Get next page: The spec requires this to be an OpusTags head
+			pi = parse_stream_page(s, pos);
+			tags = parse_opus_vorbis_comment(s, pos+pi.header_len, pi.payload_len);
+			// ...and merge replay gain intos into the tags map
+			calculate_gain(opus_head, tags);
+		}
+
+		return tags;
+	}
+
+	/**
+	 * Adds replay gain information to the tags hash map
+	 */
+	private void calculate_gain(HashMap header, HashMap tags) {
+		// Remove any unacceptable tags (Opus files must not have
+		// their own REPLAYGAIN_* fields)
+		for(String k : FORBIDDEN_TAGS) {
+			tags.remove(k);
+		}
+		// Include the gain value found in the opus header
+		int header_gain = (Integer)header.get("header_gain");
+		addTagEntry(tags, "R128_BASTP_BASE_GAIN", ""+header_gain);
+	}
+
+
+	/**
+	 * Attempts to parse an OpusHead block at given offset.
+	 * Returns an hash-map, will be empty on failure
+	 */
+	private HashMap parse_opus_head(RandomAccessFile s, long offset, long pl_len) throws IOException {
+		/* Structure:
+		 * 8 bytes of 'OpusHead'
+		 * 1 byte  version
+		 * 1 byte  channel count
+		 * 2 bytes pre skip
+		 * 4 bytes input-sample-rate
+		 * 2 bytes outputGain as Q7.8
+		 * 1 byte  channel map
+		 * --> 19 bytes
+		 */
+
+		HashMap id_hash = new HashMap();
+		byte[] buff = new byte[19];
+		if(pl_len >= buff.length) {
+			s.seek(offset);
+			s.read(buff);
+			if((new String(buff, 0, 8)).equals("OpusHead")) {
+				id_hash.put("version"      , b2u(buff[8]));
+				id_hash.put("channels"     , b2u(buff[9]));
+				id_hash.put("pre_skip"     , b2le16(buff, 10));
+				id_hash.put("sampling_rate", b2le32(buff, 12));
+				id_hash.put("header_gain"  , (int)((short)b2le16(buff, 16)));
+				id_hash.put("channel_map"  , b2u(buff[18]));
+			}
+		}
+
+		return id_hash;
+	}
+
+	/**
+	 * Parses an OpusTags section
+	 * Returns a hash map of the found tags
+	 */
+	private HashMap parse_opus_vorbis_comment(RandomAccessFile s, long offset, long pl_len) throws IOException {
+		final int magic_len = 8; // OpusTags
+		byte[] magic = new byte[magic_len];
+
+		if(pl_len < magic_len)
+			xdie("opus comment field is too short!");
+
+		// Read and check magic signature
+		s.seek(offset);
+		s.read(magic);
+
+		if((new String(magic, 0, magic_len)).equals("OpusTags") == false)
+			xdie("Damaged packet found!");
+
+		return parse_vorbis_comment(s, this, offset+magic_len, pl_len-magic_len);
+	}
+
+}
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/PageInfo.java b/app/src/main/java/github/daneren2005/dsub/util/tags/PageInfo.java
new file mode 100644
index 00000000..1081e355
--- /dev/null
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/PageInfo.java
@@ -0,0 +1,16 @@
+package github.daneren2005.dsub.util.tags;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
+public class PageInfo {
+
+	long header_len;
+	long payload_len;
+	int type;
+	boolean last_page;
+
+	public static interface PageParser {
+		PageInfo parse_stream_page(RandomAccessFile fh, long offset) throws IOException;
+	}
+}
diff --git a/app/src/main/java/github/daneren2005/dsub/util/tags/RawFile.java b/app/src/main/java/github/daneren2005/dsub/util/tags/RawFile.java
new file mode 100644
index 00000000..2fa6cf30
--- /dev/null
+++ b/app/src/main/java/github/daneren2005/dsub/util/tags/RawFile.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2017 Google Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package github.daneren2005.dsub.util.tags;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.HashMap;
+
+public class RawFile extends Common {
+
+	/**
+	 * Returns the tags of a Raw File which is just an empty HashMap.
+	 * This shall be used for raw streams with no (supported) tags.
+	 */
+	public HashMap getTags(RandomAccessFile s) throws IOException {
+		HashMap tags = new HashMap();
+		return tags;
+	}
+}
+