g711.h

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/**
 * Copyright (C) 2005 Savoir-Faire Linux inc.
 * Author: Yan Morin <[e-mail]>
 *
    Implementation of ITU-T (formerly CCITT) Recomendation G711

    Copyright (C) 2004  J.D.Medhurst (a.k.a. Tixy)

 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Library General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 *
 */
#ifndef __G711_H__
#define __G711_H__

#include "common.h"

/**
A class which implements ITU-T (formerly CCITT) Recomendation G711
"Pulse Code Modulation (PCM) of Voice Frequencies"

This encodes and decodes uniform PCM values to/from 8 bit A-law and u-Law values.

Note, the methods in this class use uniform PCM values which are of 16 bits precision,
these are 'left justified' values corresponding to the 13 and 14 bit values described
in G711.
*/
class G711
	{
public:
	/**
	Encode a 16 bit uniform PCM value into an A-Law value
	@param pcm16 A 16 bit uniform PCM value (sign extented into an int).
	             If the value doesn't lie in the range -32768 to 32767 then the
				 result is undefined.
	@return The A-Law encoded value corresponding to pcm16
	*/
	static uint8 ALawEncode(int16 pcm16);

	/**
	Encode an A-Law value into a 16 bit uniform PCM value
	@param alaw An A-Law encoded value
	@return The 16 bit uniform PCM value corresponding to alaw
	*/
	static int ALawDecode(uint8 alaw);

	/**
	Encode a 16 bit uniform PCM value into an u-Law value
	@param pcm16 A 16 bit uniform PCM value (sign extented into an int)
	             If the value doesn't lie in the range -32768 to 32767 then the
				 result is undefined.
	@return The u-Law encoded value corresponding to pcm16
	*/
	static uint8 ULawEncode(int16 pcm16);

	/**
	Encode an u-Law value into a 16 bit uniform PCM value
	@param ulaw An u-Law encoded value
	@return The 16 bit uniform PCM value corresponding to ulaw
	*/
	static int ULawDecode(uint8 ulaw);

	/**
	Convert an A-Law value into a u-law value.
	@param alaw An A-Law encoded value
	@return The u-law value.
	*/
	static uint8 ALawToULaw(uint8 alaw);

	/**
	Convert a u-Law value into an A-law value.
	@param ulaw An u-Law encoded value
	@return The A-Law value
	*/
	static uint8 ULawToALaw(uint8 ulaw);

	/**
	Encode a buffer of 16 bit uniform PCM values into A-Law values
	@param dst Pointer to location to store A-Law encoded values
	@param src Pointer to the buffer of 16 bit uniform PCM values to be encoded
	@param srcSize The size in bytes of the src buffer
	@return The number of bytes which were stored at dst (equal to srcSize>>1)
	*/
	static uint ALawEncode(uint8* dst, int16* src, uint srcSize);

	/**
	Decode a buffer of A-Law values into 16 bit uniform PCM values
	@param dst Pointer to location to store decoded 16 bit uniform PCM values
	@param src Pointer to the buffer of A-Law values to be decoded
	@param srcSize The size in bytes of the src buffer
	@return The number of bytes which were stored at dst (equal to srcSize<<1)
	*/
	static uint ALawDecode(int16* dst, uint8* src, uint srcSize);

	/**
	Encode a buffer of 16 bit uniform PCM values into u-Law values
	@param dst Pointer to location to store u-Law encoded values
	@param src Pointer to the buffer of 16 bit uniform PCM values to be encoded
	@param srcSize The size in bytes of the src buffer
	@return The number of bytes which were stored at dst (equal to srcSize>>1)
	*/
	static uint ULawEncode(uint8* dst, int16* src, uint srcSize);

	/**
	Decode a buffer of u-Law values into 16 bit uniform PCM values
	@param dst Pointer to location to store decoded 16 bit uniform PCM values
	@param src Pointer to the buffer of u-Law values to be decoded
	@param srcSize The size in bytes of the src buffer
	@return The number of bytes which were stored at dst (equal to srcSize<<1)
	*/
	static uint ULawDecode(int16* dst, uint8* src, uint srcSize);

	/**
	Convert a buffer of A-Law value into u-law values.
	@param dst Pointer to location to store u-law values
	@param src Pointer to the buffer of A-Law values to be converted
	@param srcSize The size in bytes of the src buffer
	@return The number of bytes which were stored at dst (equal to srcSize)
	*/
	static uint ALawToULaw(uint8* dst, uint8* src, uint srcSize);

	/**
	Convert a buffer of u-Law value into A-law values.
	@param dst Pointer to location to store A-law values
	@param src Pointer to the buffer of u-Law values to be converted
	@param srcSize The size in bytes of the src buffer
	@return The number of bytes which were stored at dst (equal to srcSize)
	*/
	static uint ULawToALaw(uint8* dst, uint8* src, uint srcSize);
	};

#endif