/*
* @(#)MP3ElementaryInputStream.java 1.0 2011-01-03
*
* Copyright © 2010 Werner Randelshofer, Immensee, Switzerland.
* All rights reserved.
*
* You may not use, copy or modify this file, except in compliance with the
* license agreement you entered into with Werner Randelshofer.
* For details see accompanying license terms.
*/
package ch.randelshofer.media.mp3;
import java.io.BufferedInputStream;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.util.HashMap;
import javax.sound.sampled.AudioFormat;
/**
* Facilitates reading of an MP3 elementary stream frame by frame.
* <p>
* An MP3 frame has a 32-bit header with the following contents in big endian
* order:
* <ul>
* <li>bit 31-21, MP3 Sync Word, all bits must be set</li>
* <li>bit 20-19, Version, 00=MPEG 2.5,01=reserved,10=MPEG 2, 11=MPEG 1</li>
* <li>bit 18-17, Layer, 00=reserved, 01=layer 3, 10=layer 2, 11=layer 1</li>
* <li>bit 16, Error protection, 0=16 bit CRC follows header, 1=Not protected</li>
* <li>bit 15-12, Bit Rate in kbps, interpretation depends on version and layer</li>
* <li>bit 11-10, Frequency, interpretation depends on version</li>
* <li>bit 9, Pad Bit, 0=frame is not padded, 1=frame is padded to exactly fit the bit rate</li>
* <li>bit 8, Private bit, only informative</li>
* <li>bit 7-6, Channel Mode, 00=stereo, 01=joint stereo, 10=dual channel (2 mono channels), 11=single channel (mono)</li>
* <li>bit 5-4, Mode Extension (only used with Joint Stereo), interpretation depends on version and layer</li>
* <li>bit 3, Copyright, 0=not copyrighted, 1=copyrighted</li>
* <li>bit 2, Original, 0=Copy of original media,1=original media</li>
* <li>bit 1-0, Emphasis, 00=none,01=50/15ms,10=reserved,11=CCIT J.17</li>
* </ul>
* <p>
* Reference:<br>
* <a href="http://en.wikipedia.org/wiki/MP3">http://en.wikipedia.org/wiki/MP3</a><br>
* <a href="http://www.datavoyage.com/mpgscript/mpeghdr.htm">http://www.datavoyage.com/mpgscript/mpeghdr.htm</a><br>
* <a href="http://www.mp3-tech.org/programmer/frame_header.html">http://www.mp3-tech.org/programmer/frame_header.html</a><br>
* <a href="http://lame.sourceforge.net/tech-FAQ.txt">http://lame.sourceforge.net/tech-FAQ.txt</a><br>
* <a href0"http://www.altera.com/literature/dc/1.4-2005_Taiwan_2nd_SouthernTaiwanU-web.pdf">http://www.altera.com/literature/dc/1.4-2005_Taiwan_2nd_SouthernTaiwanU-web.pdf</a><br>
*
* @author Werner Randelshofer
* @version 1.0 2011-01-03 Created.
*/
public class MP3ElementaryInputStream extends FilterInputStream {
/** Defines the "MP3" encoding. */
public final static AudioFormat.Encoding MP3 = new AudioFormat.Encoding("MP3");
private Frame frame;
private long pos;
private final static int[][] BIT_RATES = { // All values are in kbps
// V1 - MPEG Version 1
// V2 - MPEG Version 2 and Version 2.5
// L1 - Layer I
// L2 - Layer II
// L3 - Layer III
//
// V1L1, V1L2, V1L3, V2L1, V2L2&L3
{-1, -1, -1, -1, -1}, // free
{32, 32, 32, 32, 8},
{64, 48, 40, 48, 16},
{96, 56, 48, 56, 24},
{128, 64, 56, 64, 32},
{160, 80, 64, 80, 40},
{192, 96, 80, 96, 48},
{224, 112, 96, 112, 56},
{256, 128, 112, 128, 64},
{288, 160, 128, 144, 80},
{320, 192, 160, 160, 96},
{352, 224, 192, 176, 112},
{384, 256, 224, 192, 128},
{416, 320, 256, 224, 144},
{448, 384, 320, 256, 160},
{-2, -2, -2, -2, -2}, // bad
};
private final static int[][] SAMPLE_RATES = { // All values are in Hz
// V1 - MPEG Version 1
// V2 - MPEG Version 2
// V25 - MPEG Version 2.5
//
// V1, V2, V25
{44100, 22050, 11025},
{48000, 24000, 12000},
{32000, 16000, 8000},
{-1, -1, -1}, // reserved
};
/** An elementary frame. */
public static class Frame {
/** 32-bit header. */
private int header;
/** 16-bit CRC. */
private int crc;
/** The size of the data in the frame. */
private int bodySize;
/** The offset of the data in the frame. */
private long bodyOffset;
/** Creates a new frame.
*
* @param header The 32-bit Frame header
*/
public Frame(int header) {
this.header = header;
}
public int getHeader() {
return header;
}
/** Returns the version number: 1=MPEG 1, 2=MPEG 2, 25=MPEG 2.5; -1=unknown. */
public int getVersion() {
switch (getVersionCode()) {
case 0:
return 25;
case 2:
return 2;
case 3:
return 1;
default:
return -1;
}
}
/** Returns the raw version code as it is stored in the
* header. 3=MPEG 1, 2=MPEG 2, 1=reserved, 0=MPEG 2.5. */
public int getVersionCode() {
return (header >>> 19) & 3;
}
/** Returns the layer number.
* 1=Layer I, 2=Layer II, 3=Layer III, -1=unknown. */
public int getLayer() {
switch (getLayerCode()) {
case 1:
return 3;
case 2:
return 2;
case 3:
return 1;
default:
return -1;
}
}
/** Returns the raw layer code as it is stored in the header.
* 3=Layer I, 2=Layer II, 1=Layer III, 0=reserved. */
public int getLayerCode() {
return (header >>> 17) & 3;
}
/** Returns the bitrate of the frame. Returns -1 if unknown.
*/
public int getBitRate() {
if (getVersion() < 0 || getLayer() < 0) {
return -1;
}
int v = getVersion() == 1 ? 0 : 3;
int l = getVersion() == 1 ? getLayer() - 1 : (getLayer() == 1 ? 0 : 1);
return BIT_RATES[getBitRateCode()][v + l];
}
/** Returns the raw bitrate code as it is stored in the header.
*/
public int getBitRateCode() {
return (header >>> 12) & 15;
}
/** Returns true if this frame has a CRC. */
public boolean hasCRC() {
return ((header >>> 16) & 1) == 0;
}
/** Returns the CRC of this frame. The value is only valid if hasCRC() returns true. */
public int getCRC() {
return crc;
}
public boolean hasPadding() {
return ((header >>> 9) & 1) == 1;
}
/** Returns the sample rate in Hz.
* Returns -1 if unknown.
*/
public int getSampleRate() {
if (getVersion() < 0 || getLayer() < 0) {
return -1;
}
int v = getVersion() == 25 ? 2 : getVersion() - 1;
return SAMPLE_RATES[getSampleRateCode()][v];
}
/** Returns the raw sample rate code as it is stored in the header.
*/
public int getSampleRateCode() {
return (header >>> 10) & 3;
}
/** Returns the number of samples in the frame.
* It is constant and always 384 samples for Layer I and 1152 samples
* for Layer II and Layer III.
* Returns -1 if unknown.
*/
public int getSampleCount() {
if (getLayer() < 0) {
return -1;
}
return (getLayer() == 1 ? 192 : 576) * getChannelCount();
}
/** Returns the number of channels.
* @return 1=mono, 2=stereo, joint stereo or dual channel.
*/
public int getChannelCount() {
return getChannelModeCode() == 3 ? 1 : 2;
}
/** Returns the sample size in bits. Always 16 bit per sample. */
public int getSampleSize() {
return 16;
}
/** Returns the raw channel mode as stored in the header.
*
* @return 0=stereo, 1=joint stereo, 2=dual channel, 3=single channel (mono).
*/
public int getChannelModeCode() {
return (header >>> 6) & 3;
}
/** Returns the frame header as a byte array. */
public byte[] headerToByteArray() {
byte[] data = new byte[hasCRC() ? 6 : 4];
headerToByteArray(data, 0);
return data;
}
/** Writes the frame header into the specified byte array.
* Returns the number of bytes written.
*/
public int headerToByteArray(byte[] data, int offset) {
if (data.length - offset < getHeaderSize()) {
throw new IllegalArgumentException("data array is too small");
}
data[offset + 0] = (byte) (header >>> 24);
data[offset + 1] = (byte) (header >>> 16);
data[offset + 2] = (byte) (header >>> 8);
data[offset + 3] = (byte) (header >>> 0);
if (hasCRC()) {
data[offset + 4] = (byte) (crc >>> 8);
data[offset + 5] = (byte) (crc >>> 0);
}
return getHeaderSize();
}
/** Writes the frame header into the specified output stream. */
public void writeHeader(OutputStream out) throws IOException {
out.write((header >>> 24));
out.write((header >>> 16));
out.write((header >>> 8));
out.write((header >>> 0));
if (hasCRC()) {
out.write((crc >>> 8));
out.write((crc >>> 0));
}
}
/** Returns the offset of the frame in the input stream. */
public long getFrameOffset() {
return getBodyOffset() - getHeaderSize();
}
/** Returns the size of the frame in bytes.
* This size includes the header, the data and the padding.
*/
public int getFrameSize() {
return getHeaderSize() + getBodySize();
}
/** Returns the offset of the header in the input stream. */
public long getHeaderOffset() {
return getFrameOffset();
}
/** Returns the size of the header in bytes. */
public int getHeaderSize() {
return hasCRC() ? 6 : 4;
}
/** Returns the offset of the side info in the input stream. */
public long getSideInfoOffset() {
return bodyOffset;
}
/** Returns the size of the side info in bytes.
* It is 17 bytes long in a single channel frame and 32 bytes in dual
* channel or stereo channel.
*/
public int getSideInfoSize() {
return getChannelCount() == 1 ? 17 : 32;
}
/** Returns the offset of the frame body in the input stream. */
public long getBodyOffset() {
return bodyOffset;
}
/** Returns the size of the frame body in bytes.
* The body includes the side info, the audio data, and the padding.
*/
public int getBodySize() {
return bodySize;
}
/** Padding is used to fit the bit rates exactly.
* For an example: 128k 44.1kHz layer II uses a lot of 418 bytes and
* some of 417 bytes long frames to get the exact 128k bitrate. For
* Layer I slot is 32 bits long, for Layer II and Layer III slot is 8
* bits long. */
public int getPaddingSize() {
if (hasPadding()) {
return getLayer() == 1 ? 4 : 1;
}
return 0;
}
private float getFrameRate() {
return (float) getSampleRate() / getSampleCount();
}
}
public MP3ElementaryInputStream(File file) throws IOException {
super(new PushbackInputStream(new BufferedInputStream(new FileInputStream(file)), 6));
}
public MP3ElementaryInputStream(InputStream in) {
super(new PushbackInputStream(in, 6));
}
/** Gets the next frame from the input stream.
* Positions the stream in front of the frame header.
*/
public Frame getNextFrame() throws IOException {
while (frame != null && pos < frame.getBodyOffset() + frame.getBodySize()) {
long skipped = skip(frame.getBodyOffset() + frame.getBodySize() - pos);
if (skipped < 0) {
break;
}
}
while (true) {
int b = read0();
if (b == -1) {
frame = null;
break;
} else if (b == 255) {
int h0 = b;
int h1 = read0();
if (h1 != -1 && (h1 & 0xe0) == 0xe0) {
int h2 = read0();
int h3 = read0();
if (h3 != -1) {
frame = new Frame((h0 << 24) | (h1 << 16) | (h2 << 8) | h3);
if (frame.getBitRate() == -1 || frame.getLayer() == -1 || frame.getSampleRate() == -1) {
// => the header is corrupt: push back 3 bytes
PushbackInputStream pin = (PushbackInputStream) in;
pin.unread(h3);
pin.unread(h2);
pin.unread(h1);
pos -= 3;
continue;
}
int crc0 = -1, crc1 = -1;
if (frame.hasCRC()) {
crc0 = read0();
crc1 = read0();
if (crc1 == -1) {
throw new EOFException();
}
frame.crc = (crc0 << 8) | crc1;
}
frame.bodyOffset = pos;
if (frame.getBitRate() <= 0 || frame.getSampleRate() <= 0) {
frame.bodySize = 0;
} else if (frame.getLayer() == 1) {
frame.bodySize = (int) ((12000L * frame.getBitRate() / frame.getSampleRate()) * 4) - frame.getHeaderSize() + frame.getPaddingSize();
} else if (frame.getLayer() == 2 || frame.getLayer() == 3) {
if (frame.getChannelCount() == 1) {
frame.bodySize = (int) (72000L * frame.getBitRate() / (frame.getSampleRate() + frame.getPaddingSize())) - frame.getHeaderSize() + frame.getPaddingSize();
} else {
frame.bodySize = (int) (144000L * frame.getBitRate() / (frame.getSampleRate() + frame.getPaddingSize())) - frame.getHeaderSize() + frame.getPaddingSize();
}
}
PushbackInputStream pin = (PushbackInputStream) in;
if (frame.hasCRC()) {
pin.unread(crc1);
pin.unread(crc0);
pos -= 2;
}
pin.unread(h3);
pin.unread(h2);
pin.unread(h1);
pin.unread(h0);
pos -= 4;
assert pos == frame.getFrameOffset() : pos + "!=" + frame.getFrameOffset();
break;
}
}
}
}
return frame;
}
/** Returns the current frame. */
public Frame getFrame() {
return frame;
}
/** Gets the format of the current frame.
* Returns null if the input stream is not positioned on a frame, or the frame
* is not valid.
* @return AudioFormat of current frame or null.
*/
public AudioFormat getFormat() {
if (frame == null) {
return null;
} else {
HashMap<String, Object> properties = new HashMap<String, Object>();
properties.put("vbr", true);
return new AudioFormat(MP3, //
frame.getSampleRate(), frame.getSampleSize(), frame.getChannelCount(),//
frame.getFrameSize(), frame.getFrameRate(), true, properties);
}
}
private int read0() throws IOException {
int b = super.read();
if (b != -1) {
pos++;
}
return b;
}
/** Reads a byte from the current frame (its header and its data).
* Returns -1 on an attempt to read past the end of the frame.
*/
@Override
public int read() throws IOException {
if (frame == null || pos >= frame.getBodyOffset() + frame.getBodySize()) {
return -1;
}
return read0();
}
/** Reads up to {@code len} bytes from the current frame (its header and its data).
* May read less then {@code len} bytes. Returns the actual number of bytes read.
* Returns -1 on an attempt to read past the end of the frame.
*/
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (frame == null) {
return -1;
}
int maxlen = (int) (frame.getBodyOffset() + frame.getBodySize() - pos);
if (maxlen < 1) {
return -1;
}
len = Math.min(maxlen, len);
int count = super.read(b, off, len);
if (count != -1) {
pos += count;
}
return count;
}
/**
* Reads {@code b.length} bytes from the current frame (its header and its data).
* @throws {@code IOException} on an attempt to read past the end of the frame.
*/
public final void readFully(byte b[]) throws IOException {
readFully(b, 0, b.length);
}
/**
* Reads {@code len} bytes from the current frame (its header and its data).
* @throws {@code IOException} on an attempt to read past the end of the frame.
*/
public final void readFully(byte b[], int off, int len) throws IOException {
if (len < 0) {
throw new IndexOutOfBoundsException();
}
int n = 0;
while (n < len) {
int count = in.read(b, off + n, len - n);
if (count < 0) {
throw new EOFException();
}
n += count;
pos += count;
}
}
/** Skips up to {@code n} bytes from the current frame (its header and its data).
* Returns the actual number of bytes that have been skipped.
* Returns -1 on an attempt to skip past the end of the frame.
*/
@Override
public long skip(long n) throws IOException {
if (frame == null) {
return -1;
}
int maxlen = (int) (frame.getBodyOffset() + frame.getBodySize() - pos);
if (maxlen < 1) {
return -1;
}
n = Math.min(maxlen, n);
long skipped = in.skip(n);
if (skipped > 0) {
pos += skipped;
}
return skipped;
}
/**
* Returns the current position in the stream.
* @return The stream position.
*/
public long getStreamPosition() {
return pos;
}
}