1 package com.googlecode.mp4parser.boxes.mp4.objectdescriptors; 2 3 import java.nio.ByteBuffer; 4 5 public class BitReaderBuffer { 6 7 private ByteBuffer buffer; 8 int initialPos; 9 int position; 10 11 public BitReaderBuffer(ByteBuffer buffer) { 12 this.buffer = buffer; 13 initialPos = buffer.position(); 14 } 15 16 public int readBits(int i) { 17 byte b = buffer.get(initialPos + position / 8); 18 int v = b < 0 ? b + 256 : b; 19 int left = 8 - position % 8; 20 int rc; 21 if (i <= left) { 22 rc = (v << (position % 8) & 0xFF) >> ((position % 8) + (left - i)); 23 position += i; 24 } else { 25 int now = left; 26 int then = i - left; 27 rc = readBits(now); 28 rc = rc << then; 29 rc += readBits(then); 30 } 31 buffer.position(initialPos + (int) Math.ceil((double) position / 8)); 32 return rc; 33 } 34 35 public int getPosition() { 36 return position; 37 } 38 39 public int byteSync() { 40 int left = 8 - position % 8; 41 if (left == 8) { 42 left = 0; 43 } 44 readBits(left); 45 return left; 46 } 47 48 public int remainingBits() { 49 return buffer.limit() * 8 - position; 50 } 51 } 52
