common.c

功能非常完善的MP3编译码器,输入文件WAV或AIFF,能够方便的嵌入到你自己的系统当中.

/*
			(c) Copyright 1998, 1999 - Tord Jansson
			=======================================

		This file is part of the BladeEnc MP3 Encoder, based on
		ISO's reference code for MPEG Layer 3 compression, and might
		contain smaller or larger sections that are directly taken
		from ISO's reference code.

		All changes to the ISO reference code herein are either
		copyrighted by Tord Jansson ([e-mail])
		or sublicensed to Tord Jansson by a third party.

	BladeEnc is free software; you can redistribute this file
	and/or modify it under the terms of the GNU Lesser General Public
	License as published by the Free Software Foundation; either
	version 2.1 of the License, or (at your option) any later version.

*/

/***********************************************************************
*
*  Global Include Files
*
***********************************************************************/

#include    "common.h"
#include	<string.h> /* 1995-07-11 shn */
#include	<ctype.h>
#include <stdlib.h>

/***********************************************************************
*
*  Global Variable Definitions
*
***********************************************************************/

/* 1: MPEG-1, 0: MPEG-2 LSF, 1995-07-11 shn */
double  s_freq[2][4] = {{22.05, 24, 16, 0}, {44.1, 48, 32, 0}};

/* 1: MPEG-1, 0: MPEG-2 LSF, 1995-07-11 shn */
int     bitratex[2][15] = {
          {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160},
					{0,32,40,48,56,64,80,96,112,128,160,192,224,256,320}
        };



/***********************************************************************
*
* Using the decoded info the appropriate possible quantization per
* subband table is loaded
*
**********************************************************************/


void hdr_to_frps(frame_params *fr_ps) /* interpret data in hdr str to fields in fr_ps */
{
layer *hdr = fr_ps->header;     /* (or pass in as arg?) */

    fr_ps->actual_mode = hdr->mode;
    fr_ps->stereo = (hdr->mode == MPG_MD_MONO) ? 1 : 2;
		fr_ps->sblimit = SBLIMIT;
    fr_ps->jsbound = fr_ps->sblimit;
}






/*******************************************************************************
*
*  Allocate number of bytes of memory equal to "block".
*
*******************************************************************************/

void  *mem_alloc(unsigned long block, char *item)
{

    void    *ptr;

    ptr = (void *) malloc(block*2);

    memset(ptr, 0, block*2);

    return(ptr);
}


/****************************************************************************
*
*  Free memory pointed to by "*ptr_addr".
*
*****************************************************************************/

void    mem_free( void **ptr_addr)
{
  if (*ptr_addr != NULL)
	{
    free(*ptr_addr);
    *ptr_addr = NULL;
  }
}