package cn.org.hentai.jtt1078.server.audio;
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import cn.org.hentai.jtt1078.entity.AudioSendData;
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import cn.org.hentai.jtt1078.entity.enums.ProtocolVersion;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.MessageToByteEncoder;
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import lombok.extern.slf4j.Slf4j;
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import java.nio.ByteBuffer;
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import java.nio.ByteOrder;
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@Slf4j
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public class Jt1078AudioEncoder extends MessageToByteEncoder<AudioSendData> {
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@Override
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protected void encode(ChannelHandlerContext ctx, AudioSendData audioData, ByteBuf out) throws Exception {
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try {
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// 1. 转换音频格式为PCM
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byte[] pcmData = audioData.getAudioBytes();
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// 2. 编码为G.711 A-law
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byte[] g711Data = encodePcmToG711A(pcmData);
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// 3. 构建JT1078协议包
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buildJt1078Packet(out, audioData, g711Data);
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} catch (Exception e) {
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log.error("音频编码失败", e);
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throw e;
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}
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}
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private byte[] encodePcmToG711A(byte[] pcmData) {
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byte[] alawData = new byte[pcmData.length / 2];
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ByteBuffer buffer = ByteBuffer.wrap(pcmData);
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buffer.order(ByteOrder.LITTLE_ENDIAN);
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for (int i = 0; i < alawData.length; i++) {
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short pcmSample = buffer.getShort();
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alawData[i] = linearToALaw(pcmSample);
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}
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return alawData;
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}
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private void buildJt1078Packet(ByteBuf out, AudioSendData audioData, byte[] g711Data) {
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// 1. JT1078 Header
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out.writeBytes(new byte[]{0x30, 0x31, 0x63, 0x64});
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// 2. Payload Type (06 = Audio Stream)
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out.writeByte(0x81);
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out.writeByte(0x86);
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// 3. Sequence Number
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out.writeShort(audioData.getSequenceNumber());
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// 4. SIM (BCD, 10 bytes)
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int simLength = (audioData.getProtocolVersion() == ProtocolVersion.V2013) ? 6 : 10;
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byte[] simBcd = encodeSimToBcd(audioData.getSim(), simLength);
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// byte[] simBcd = encodeSimToBcd(audioData.getSim(), 6); // 可能需要更长
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out.writeBytes(simBcd);
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// 5. Channel
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out.writeByte(audioData.getChannel());
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// 6. Data Type (Audio) + Frame Info (Atomic)
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out.writeByte(0x30);
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// 7. Timestamp (8 bytes)
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out.writeLong(System.currentTimeMillis());
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// 8. Data Length (2 bytes)
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out.writeShort(g711Data.length);
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// 9. Audio Data (G.711 A-law)
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out.writeBytes(g711Data);
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// 打印十六进制字符串（推荐）
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//log.info("发送的 JT1078 报文（Hex）: {}", ByteBufUtil.hexDump(out));
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}
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private byte[] encodeSimToBcd(String sim, int length) {
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// BCD编码每个字节存2位数字，因此需要2倍长度
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int digitCount = length * 2;
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// 补全或截断SIM卡号
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String normalizedSim = sim.length() > digitCount
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? sim.substring(0, digitCount)
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: String.format("%-" + digitCount + "s", sim).replace(' ', '0');
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byte[] bcd = new byte[length];
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for (int i = 0; i < digitCount; i += 2) {
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int high = Character.digit(normalizedSim.charAt(i), 10);
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int low = Character.digit(normalizedSim.charAt(i + 1), 10);
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bcd[i / 2] = (byte) ((high << 4) | low);
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}
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return bcd;
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}
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private byte linearToALaw(short pcm) {
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// G.711 A-law编码算法实现
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int sign = (pcm & 0x8000) >> 8;
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if (sign != 0) {
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pcm = (short) -pcm;
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}
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if (pcm > 32767) pcm = 32767;
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int exponent = 7;
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int mask = 0x4000;
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while ((pcm & mask) == 0 && exponent > 0) {
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exponent--;
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mask >>= 1;
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}
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int mantissa = (pcm >> (exponent == 0 ? 4 : exponent + 3)) & 0x0F;
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byte alaw = (byte) (sign | (exponent << 4) | mantissa);
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return (byte) (alaw ^ 0xD5);
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}
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}
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