Jtt1078Decoder.java
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package com.genersoft.iot.vmp.jtt1078.server;
import com.genersoft.iot.vmp.jtt1078.util.ByteHolder;
import com.genersoft.iot.vmp.jtt1078.util.Packet;
public class Jtt1078Decoder {
// 加大缓冲区，防止高清视频流溢出
ByteHolder buffer = new ByteHolder(4096 * 20);
private static final int HEADER_MAGIC = 0x30316364;
public void write(byte[] block) {
buffer.write(block);
}
public void write(byte[] block, int startIndex, int length) {
byte[] buff = new byte[length];
System.arraycopy(block, startIndex, buff, 0, length);
write(buff);
}
public Packet decode() {
// 1. 搜寻包头 (关键改造)
while (this.buffer.size() >= 4) {
if ((buffer.getInt(0) & 0x7fffffff) == HEADER_MAGIC) {
break;
}
// 丢弃无效字节
byte[] trash = new byte[1];
buffer.read(trash);
}
if (this.buffer.size() < 30) return null;
int lengthOffset = 28;
int dataType = (this.buffer.get(15) >> 4) & 0x0f;
if (dataType == 0x04) lengthOffset = 28 - 8 - 2 - 2;
else if (dataType == 0x03) lengthOffset = 28 - 4;
int bodyLength = this.buffer.getShort(lengthOffset);
int packetLength = bodyLength + lengthOffset + 2;
if (this.buffer.size() < packetLength) return null;
byte[] block = new byte[packetLength];
this.buffer.sliceInto(block, packetLength);
return Packet.create(block);
}
}