pcm.h

G726标准的24kbps和40kbps两种比特率的音频编解码算法源代码

#define SIGN_BIT	(0x80)		/* Sign bit for a A-law byte. */
#define QUANT_MASK	(0xf)		/* Quantization field mask. */
#define NSEGS		(8)		/* Number of A-law segments. */
#define SEG_SHIFT	(4)		/* Left shift for segment number. */
#define SEG_MASK	(0x70)		/* Segment field mask. */
#define BIAS		(0x84)      /* Bias for linear code. */

unsigned char linear2alaw(short pcm_val);
short alaw2linear(unsigned char a_val);

unsigned char linear2ulaw(int pcm_val); /* 2's complement (16-bit range) */ 
int ulaw2linear(unsigned char u_val);