wav_ima_adpcm.c

来自「LastWave」· C语言 代码 · 共 624 行 · 第 1/2 页

/*
** Copyright (C) 1999 Erik de Castro Lopo <[e-mail]>
**  
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU 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 General Public License for more details.
** 
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software 
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/


#include	<stdio.h>
#include	<string.h>
#include	<math.h>

#include	"sndfile.h"
#include	"sfendian.h"
#include	"common.h"
#include	"wav.h"

typedef struct
{	unsigned int	channels, blocksize, samplesperblock, blocks ; 
	int				blockcount, samplecount ;
	int				previous [2] ;
	int				stepindex [2] ;
	unsigned char	*block ;
	short			*samples ;
	unsigned char	data	[4] ; /* Dummy size */
} IMA_PRIVATE ;

/*============================================================================================
** Predefined IMA ADPCM data.
*/

static int ima_index_adjust [16] = 
{	-1, -1, -1, -1,		/* +0 - +3, decrease the step size */
     2,  4,  6,  8,     /* +4 - +7, increase the step size */
    -1, -1, -1, -1,		/* -0 - -3, decrease the step size */
     2,  4,  6,  8,		/* -4 - -7, increase the step size */
} ;

static int ima_step_size [89] = 
{	7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 
	50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 
	253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963, 
	1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327, 
	3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442,
	11487, 12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 
	32767
} ;

static	int	__ima_read_block (SF_PRIVATE *psf, IMA_PRIVATE *pima) ;
static	int __ima_read (SF_PRIVATE *psf, IMA_PRIVATE *pima, short *ptr, int len) ;

static	int	__ima_write_block (SF_PRIVATE *psf, IMA_PRIVATE *pima) ;
static	int __ima_write (SF_PRIVATE *psf, IMA_PRIVATE *pima, short *ptr, int len) ;

static	unsigned int srate2blocksize (unsigned int srate) ;

/*============================================================================================
** IMA ADPCM Read Functions.
*/

int	__ima_reader_init (SF_PRIVATE *psf, WAV_FMT *fmt)
{	IMA_PRIVATE		*pima ;
	unsigned int	pimasize ;
	int 			count ;
	
	pimasize = sizeof (IMA_PRIVATE) + fmt->ima.blockalign + 3 * fmt->ima.channels * fmt->ima.samplesperblock ;

	if (! (psf->fdata = malloc (pimasize)))
		return SFE_MALLOC_FAILED ;
	pima = (IMA_PRIVATE*) psf->fdata ;
	memset (pima, 0, pimasize) ;
	
	pima->block   = (unsigned char*) pima->data ;
	pima->samples = (short*) (pima->data + fmt->ima.blockalign) ;
	
	pima->channels        = fmt->ima.channels ;
	pima->blocksize       = fmt->ima.blockalign ;
	pima->samplesperblock = fmt->ima.samplesperblock ;

	if (psf->datalength % pima->blocksize)
	{	__psf_sprintf (psf, "*** Warning : data chunk seems to be truncated.\n") ;
		pima->blocks = psf->datalength / pima->blocksize  + 1 ;
		}
	else
		pima->blocks = psf->datalength / pima->blocksize ;
		
	count = 2 * (pima->blocksize - 4 * pima->channels) / pima->channels + 1 ;
	if (pima->samplesperblock != count)
		__psf_sprintf (psf, "*** Warning : samplesperblock shoud be %d.\n", count) ;

	psf->sf.samples = pima->samplesperblock * pima->blocks ;

	__ima_read_block (psf, pima) ;	/* Read first block. */
	
	return 0 ;
} /* __ima_reader_init */

static
int		__ima_read_block (SF_PRIVATE *psf, IMA_PRIVATE *pima)
{	int		chan, k, current, blockindex, index, indexstart ;
	short	step, diff, bytecode, stepindex [2] ;
	
	pima->blockcount ++ ;
	pima->samplecount = 0 ;
	
	if (pima->blockcount > pima->blocks)
	{	memset (pima->samples, 0, pima->samplesperblock * pima->channels * sizeof (short)) ;
		return 1 ;
		} ;

	if ((k = fread (pima->block, 1, pima->blocksize, psf->file)) != pima->blocksize)
		__psf_sprintf (psf, "*** Warning : short read (%d != %d).\n", k, pima->blocksize) ;

	/* Read and check the block header. */
	
	for (chan = 0 ; chan < pima->channels ; chan++)
	{	current = pima->block [chan*4] | (pima->block [chan*4+1] << 8) ;
		if (current & 0x8000)
			current -= 0x10000 ;
			
		stepindex [chan] = pima->block [chan*4+2] ;
		if (stepindex [chan] < 0)
			stepindex [chan] = 0 ;
		else if (stepindex [chan] > 88)
			stepindex [chan] = 88 ;

		if (pima->block [chan*4+3] != 0)
			__psf_sprintf (psf, "IMA ADPCM synchronisation error.\n") ;
		
		pima->samples [chan] = current ;

		/* __psf_sprintf (psf, "block %d : channel %d (current, index) : (%d, %d)\n", 
		**	pima->blockcount, chan,  current, stepindex [chan]) ;
		*/
		} ;
		
	/* Pull apart the packed 4 bit samples and store them in their
	** correct sample positions.
	*/
	
	blockindex = 4 * pima->channels ;
	
	indexstart = pima->channels ;
	while (blockindex <  pima->blocksize)
	{	for (chan = 0 ; chan < pima->channels ; chan++)
		{	index = indexstart + chan ;
			for (k = 0 ; k < 4 ; k++)
			{	bytecode = pima->block [blockindex++] ;
				pima->samples [index] = bytecode & 0x0F ;
				index += pima->channels ;
				pima->samples [index] = (bytecode >> 4) & 0x0F ;
				index += pima->channels ;
				} ;
			} ;
		indexstart += 8 * pima->channels ;
		} ;
		
	/* Decode the encoded 4 bit samples. */
	
	for (k = pima->channels ; k < (pima->samplesperblock * pima->channels) ; k ++)
	{	chan = (pima->channels > 1) ? (k % 2) : 0 ;

		bytecode = pima->samples [k] & 0xF ;
		
		step = ima_step_size [stepindex [chan]] ;
		current = pima->samples [k - pima->channels] ;
  
		diff = step >> 3 ;
		if (bytecode & 1) 
			diff += step >> 2 ;
		if (bytecode & 2) 
			diff += step >> 1 ;
		if (bytecode & 4) 
			diff += step ;
		if (bytecode & 8) 
			diff = -diff ;

		current += diff ;

		if (current > 32767) 
			current = 32767;
		else if (current < -32768) 
			current = -32768 ;

		stepindex [chan] += ima_index_adjust [bytecode] ;
	
		if (stepindex [chan] < 0) 
			stepindex [chan] = 0 ;
		else if (stepindex [chan] > 88) 
			stepindex [chan] = 88 ;

		pima->samples [k] = current ;
		} ;

	return 1 ;
} /* __ima_read_block */

static
int __ima_read (SF_PRIVATE *psf, IMA_PRIVATE *pima, short *ptr, int len)
{	int		count, total = 0, index = 0 ;

	while (index < len)
	{	if (pima->blockcount >= pima->blocks && pima->samplecount >= pima->samplesperblock)
		{	memset (&(ptr[index]), 0, (len - index) * sizeof (short)) ;
			return total ;
			} ;
		
		if (pima->samplecount >= pima->samplesperblock)
			__ima_read_block (psf, pima) ;
		
		count = (pima->samplesperblock - pima->samplecount) * pima->channels ;
		count = (len - index > count) ? count : len - index ;
		
		memcpy (&(ptr[index]), &(pima->samples [pima->samplecount * pima->channels]), count * sizeof (short)) ;
		index += count ;
		pima->samplecount += count / pima->channels ;
		total = index ;
		} ;

	return total ;		
} /* __ima_read */

int		__ima_read_s (SF_PRIVATE *psf, short *ptr, int len)
{	IMA_PRIVATE 	*pima ; 
	int				total ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_PRIVATE*) psf->fdata ;
	
	total = __ima_read (psf, pima, ptr, len) ;

	return total ;
} /* __ima_read_s */

int		__ima_read_i  (SF_PRIVATE *psf, int *ptr, int len)
{	IMA_PRIVATE *pima ; 
	short		*sptr ;
	int			k, bufferlen, readcount = 0, count ;
	int			index = 0, total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_PRIVATE*) psf->fdata ;
	
	sptr = (short*) psf->buffer ;
	bufferlen = ((SF_BUFFER_LEN / psf->blockwidth) * psf->blockwidth) / sizeof (short) ;
	while (len > 0)
	{	readcount = (len >= bufferlen) ? bufferlen : len ;
		count = __ima_read (psf, pima, sptr, readcount) ;
		for (k = 0 ; k < readcount ; k++)
			ptr [index+k] = (int) (sptr [k]) ;
		index += readcount ;
		total += count ;
		len -= readcount ;
		} ;
	return total ;
} /* __ima_read_i */

int		__ima_read_d  (SF_PRIVATE *psf, double *ptr, int len, int normalize)
{	IMA_PRIVATE *pima ; 
	short		*sptr ;
	int			k, bufferlen, readcount = 0, count ;
	int			index = 0, total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_PRIVATE*) psf->fdata ;
	
	sptr = (short*) psf->buffer ;
	bufferlen = ((SF_BUFFER_LEN / psf->blockwidth) * psf->blockwidth) / sizeof (short) ;
	while (len > 0)
	{	readcount = (len >= bufferlen) ? bufferlen : len ;
		count = __ima_read (psf, pima, sptr, readcount) ;
		for (k = 0 ; k < readcount ; k++)
			ptr [index+k] = (double) (sptr [k]) ;
		index += readcount ;
		total += count ;
		len -= readcount ;
		} ;
	return total ;
} /* __ima_read_d */


off_t    __ima_seek   (SF_PRIVATE *psf, off_t offset, int whence)
{	IMA_PRIVATE *pima ; 
	int			newblock, newsample ;
	
	if (! psf->fdata)
		return 0 ;
	pima = (IMA_PRIVATE*) psf->fdata ;

	if (! (psf->blockwidth && psf->datalength && psf->dataoffset))
	{	psf->error = SFE_BAD_SEEK ;
		return	((off_t) -1) ;
		} ;
		
	switch (whence)
	{	case SEEK_SET :
				if (offset < 0 || offset > pima->blocks * pima->samplesperblock)
				{	psf->error = SFE_BAD_SEEK ;