package cn.org.hentai.jtt1078.util;
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public class G711Util {
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// 优化的G.711A解码方法
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public static byte[] decodeG711AFast(byte[] alawData) {
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byte[] pcmData = new byte[alawData.length * 2];
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for (int i = 0; i < alawData.length; i++) {
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short pcm = ALAW_TABLE[alawData[i] & 0xFF];
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pcmData[i * 2] = (byte) (pcm & 0xFF);
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pcmData[i * 2 + 1] = (byte) (pcm >> 8);
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}
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return pcmData;
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}
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// A-law解码查找表
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private static final short[] ALAW_TABLE = new short[256];
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static {
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for (int i = 0; i < 256; i++) {
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int alaw = i ^ 0x55;
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int sign = alaw & 0x80;
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int exponent = (alaw & 0x70) >> 4;
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int data = alaw & 0x0F;
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data = (data << 4) + 8;
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if (exponent != 0) data += 0x100;
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if (exponent > 1) data <<= (exponent - 1);
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ALAW_TABLE[i] = (short) (sign == 0 ? data : -data);
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}
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}
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}
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