1 /* 2 Copyright (c) 2011 Stanislav Vitvitskiy 3 4 Permission is hereby granted, free of charge, to any person obtaining a copy of this 5 software and associated documentation files (the "Software"), to deal in the Software 6 without restriction, including without limitation the rights to use, copy, modify, 7 merge, publish, distribute, sublicense, and/or sell copies of the Software, and to 8 permit persons to whom the Software is furnished to do so, subject to the following 9 conditions: 10 11 The above copyright notice and this permission notice shall be included in all copies or 12 substantial portions of the Software. 13 14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 15 INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR 16 PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 17 FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 18 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE 19 OR OTHER DEALINGS IN THE SOFTWARE. 20 */ 21 package com.googlecode.mp4parser.h264.read; 22 23 import com.googlecode.mp4parser.h264.CharCache; 24 25 import java.io.IOException; 26 import java.io.InputStream; 27 28 /** 29 * A dummy implementation of H264 RBSP reading 30 * 31 * @author Stanislav Vitvitskiy 32 */ 33 public class BitstreamReader { 34 private InputStream is; 35 private int curByte; 36 private int nextByte; 37 int nBit; 38 protected static int bitsRead; 39 40 protected CharCache debugBits = new CharCache(50); 41 BitstreamReader(InputStream is)42 public BitstreamReader(InputStream is) throws IOException { 43 this.is = is; 44 curByte = is.read(); 45 nextByte = is.read(); 46 } 47 48 /* 49 * (non-Javadoc) 50 * 51 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#read1Bit() 52 */ read1Bit()53 public int read1Bit() throws IOException { 54 if (nBit == 8) { 55 advance(); 56 if (curByte == -1) { 57 return -1; 58 } 59 } 60 int res = (curByte >> (7 - nBit)) & 1; 61 nBit++; 62 63 debugBits.append(res == 0 ? '0' : '1'); 64 ++bitsRead; 65 66 return res; 67 } 68 69 /* 70 * (non-Javadoc) 71 * 72 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#readNBit(int) 73 */ readNBit(int n)74 public long readNBit(int n) throws IOException { 75 if (n > 64) 76 throw new IllegalArgumentException("Can not readByte more then 64 bit"); 77 78 long val = 0; 79 80 for (int i = 0; i < n; i++) { 81 val <<= 1; 82 val |= read1Bit(); 83 } 84 85 return val; 86 } 87 advance()88 private void advance() throws IOException { 89 curByte = nextByte; 90 nextByte = is.read(); 91 nBit = 0; 92 } 93 94 /* 95 * (non-Javadoc) 96 * 97 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#readByte() 98 */ readByte()99 public int readByte() throws IOException { 100 if (nBit > 0) { 101 advance(); 102 } 103 104 int res = curByte; 105 106 advance(); 107 108 return res; 109 } 110 111 /* 112 * (non-Javadoc) 113 * 114 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#moreRBSPData() 115 */ moreRBSPData()116 public boolean moreRBSPData() throws IOException { 117 if (nBit == 8) { 118 advance(); 119 } 120 int tail = 1 << (8 - nBit - 1); 121 int mask = ((tail << 1) - 1); 122 boolean hasTail = (curByte & mask) == tail; 123 124 return !(curByte == -1 || (nextByte == -1 && hasTail)); 125 } 126 getBitPosition()127 public long getBitPosition() { 128 return (bitsRead * 8 + (nBit % 8)); 129 } 130 131 /* 132 * (non-Javadoc) 133 * 134 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#readRemainingByte() 135 */ readRemainingByte()136 public long readRemainingByte() throws IOException { 137 return readNBit(8 - nBit); 138 } 139 140 /* 141 * (non-Javadoc) 142 * 143 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#next_bits(int) 144 */ peakNextBits(int n)145 public int peakNextBits(int n) throws IOException { 146 if (n > 8) 147 throw new IllegalArgumentException("N should be less then 8"); 148 if (nBit == 8) { 149 advance(); 150 if (curByte == -1) { 151 return -1; 152 } 153 } 154 int[] bits = new int[16 - nBit]; 155 156 int cnt = 0; 157 for (int i = nBit; i < 8; i++) { 158 bits[cnt++] = (curByte >> (7 - i)) & 0x1; 159 } 160 161 for (int i = 0; i < 8; i++) { 162 bits[cnt++] = (nextByte >> (7 - i)) & 0x1; 163 } 164 165 int result = 0; 166 for (int i = 0; i < n; i++) { 167 result <<= 1; 168 result |= bits[i]; 169 } 170 171 return result; 172 } 173 174 /* 175 * (non-Javadoc) 176 * 177 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#byte_aligned() 178 */ isByteAligned()179 public boolean isByteAligned() { 180 return (nBit % 8) == 0; 181 } 182 183 /* 184 * (non-Javadoc) 185 * 186 * @see ua.org.jplayer.javcodec.h264.RBSPInputStream#close() 187 */ close()188 public void close() throws IOException { 189 } 190 getCurBit()191 public int getCurBit() { 192 return nBit; 193 } 194 }