im726.h

G.726带测试和在DM642实现的完整工程。测试程序可修改自行填入数据。实现部分设计具体产品板的定义

#ifndef IM726_H
#define IM726_H

#ifdef __cplusplus
extern "C" {
#endif

typedef unsigned int G726HAND;

/*
	Init G726 Encoder/Decoder
	@return 0 - Success, 1 - Error
	
*/

extern unsigned int G726_init(G726HAND *phG726);

/*
	将PCM数据编码为G726流

	Each ADPCM value only occupies the minimum number of bits required and successive
	values occupy adjacent bit positions. E.g. Four 3 bit ADPCM values (A,B,C,D) are
	stored in two successive bytes like this: 1st byte: ccbbbaaa 2nd byte: ----dddc.
	Note that any unused bits in the last byte are set to zero.


	@param dst		 Pointer to location to store ADPCM values.
	@param dstOffset Offset from \a dst, in number-of-bits, at which the decoded values
					 will be stored. I.e. the least significant bit of the first ADPCM
					 value will be stored in byte 
					 @code	 dst[dstOffset>>3]	 @endcode
					 at bit position
					 @code	 dstOffset&7		 @endcode
					 Where the bit 0 is the least significant bit in a byte
					 and bit 7 is the most significant bit.
	@param src		 Pointer to the buffer of PCM values to be converted.
	@param srcSize	 The size in bytes of the buffer at \a src.
					 Must be a multiple of the size of a single PCM sample.

	@return 		 The number of bits were stored in the \a dst buffer.
*/
extern unsigned int G726_Encode(G726HAND h, void* dst, int dstOffset, const void* src, unsigned srcSize);

/*
	Decode a buffer of ADPCM values into 16 bit uniform PCM values.

	Each ADPCM value only occupies the minimum number of bits required and successive
	values occupy adjacent bit positions. E.g. Four 3 bit ADPCM values (A,B,C,D) are
	stored in two successive bytes like this: 1st byte: ccbbbaaa 2nd byte: ----dddc.

	@param dst		 Pointer to location to store PCM values.
	@param src		 Pointer to the buffer of ADPCM values to be converted.
	@param srcOffset Offset from \a src, in number-of-bits, from which the ADPCM values
					 will be read. I.e. the least significant bit of the first ADPCM
					 value will be read from byte 
					 @code	 src[srcOffset>>3]	 @endcode
					 at bit position
					 @code	 srcOffset&7		 @endcode
					 Where the bit 0 is the least significant bit in a byte
					 and bit 7 is the most significant bit.
	@param srcSize	 The number of bits to be read from the buffer at \a src.
					 Must be a multiple of the size of a single ADPCM value.

	@return 		 The number of bytes which were stored in the \a dst buffer.
*/
extern unsigned int G726_Decode(G726HAND h, void* dst, const void* src, int srcOffset, unsigned srcSize);

/*
	Clears the internal state variables to their 'reset' values.
	Call this function before startings to decode/encode a new audio stream.
*/
extern unsigned int G726_Reset(G726HAND h);

/*
	Close G726 instance
*/
extern unsigned int G726_Close(G726HAND h);


/* Call Sample

	G726HAND g726enc, g726dec;
	short src[128], dst[128];
	
	int lenBits, lenBytes, i;

	for(i = 0; i < 128; i++)
		src[i] = rand(); //init src pcm buf to rand value
 	
	G726_init(&g726enc); // init encoder
	G726_init(&g726dec); // init decoder

	lenBits = G726_Encode(g726enc, dst, 0, src, 128);		// encode 
	lenBytes = G726_Decode(g726dec, src, dst, 0, lenBits);	// decode

*/

#ifdef __cplusplus
}
#endif

#endif