16K G711转8K PCM

int pcmBufLen = 480;
short pcmBuf[pcmBufLen] = {0};
short pcmResampleBuf[pcmBufLen/2] = {0};
int g711BufLen = 480;
unsigned char g711Buf[g711BufLen] = {0};

int itmpDataLen = datasize - sizeof(FrameHead);
int itmpPackCnt = (itmpDataLen + 479) / 480;

for (int i = 0; i < itmpPackCnt;)
{
	memset(pcmBuf, 0, sizeof(pcmBuf));
	memset(g711Buf, 0, sizeof(g711Buf));
	memcpy(g711Buf, (unsigned char *)((unsigned char *)pFrame + sizeof(FrameHead) + (pFrame->FrameSize * i)), 480);

	short data = 0;
	short seg = 0;

	/* g711 转 pcm 过程 */
	for(int j = 0; j < pcmBufLen; j++)
	{
		g711Buf[j] ^= 0x55;

		data = (g711Buf[j] & 0xF) << 4;
		seg = (g711Buf[j] & 0x70) >> 4;

		switch(seg)
		{
			case 0:
				data += 8;
				break;
			case 1:
				data += 0x108;
				break;
			default:
				data += 0x108;
				data <<= seg - 1;
		}

		if(g711Buf[j] & 0x80)
		{
			pcmBuf[j] = data;
		}
		else
		{
			pcmBuf[j] = -data;
		}

		/* 采样率16K转8K */
		if(j % 2 == 0)
		{
			pcmResampleBuf[j / 2] = pcmBuf[j];
			
		}
			
	}
}