wav_ms_adpcm.c

Vovida 社区开源的 SIP 协议源码

	if (psf->mode == SF_MODE_READ)
	{	fseek (psf->file, (int) (psf->dataoffset + newblock * pms->blocksize), SEEK_SET) ;
		pms->blockcount  = newblock ;
		msadpcm_read_block (psf, pms) ;
		pms->samplecount = newsample ;
		}
	else
	{	/* What to do about write??? */ 
		psf->error = SFE_BAD_SEEK ;
		return	((off_t) -1) ;
		} ;

	psf->current = newblock * pms->samplesperblock + newsample ;
	return psf->current ;
} /* msadpcm_seek */

/*==========================================================================================
** MS ADPCM Write Functions.
*/

int	
wav_msadpcm_writer_init (SF_PRIVATE *psf)
{	MSADPCM_PRIVATE	*pms ;
	unsigned int 	pmssize, blockalign, samplesperblock ;
	
	blockalign      = srate2blocksize (psf->sf.samplerate) ;	
	samplesperblock = 2 + 2 * (blockalign - 7 * psf->sf.channels) / psf->sf.channels ;
	
	pmssize = sizeof (MSADPCM_PRIVATE) + blockalign + 3 * psf->sf.channels * samplesperblock ;

	if (! (psf->fdata = malloc (pmssize)))
		return SFE_MALLOC_FAILED ;
	pms = (MSADPCM_PRIVATE*) psf->fdata ;
	memset (pms, 0, pmssize) ;
	
	pms->channels        = psf->sf.channels ;
	pms->blocksize       = blockalign ;
	pms->samplesperblock = samplesperblock ;

	pms->block   = (unsigned char*) pms->dummydata ;
	pms->samples = (short*) (pms->dummydata + blockalign) ;
	
	pms->samplecount = 0 ;
	
	msadpcm_write_header (psf) ;
	
	psf->write_short  = (func_short)   msadpcm_write_s ;
	psf->write_int    = (func_int)     msadpcm_write_i ;
	psf->write_float  = (func_float)   msadpcm_write_f ;
	psf->write_double = (func_double)  msadpcm_write_d ;
	
	psf->seek_func    = (func_seek)    msadpcm_seek ;
	psf->close        = (func_close)   msadpcm_close ;
	psf->write_header = (func_wr_hdr)  msadpcm_write_header ;

	return 0 ;
} /* wav_msadpcm_writer_init */

/*==========================================================================================
*/

static int		
msadpcm_write_block (SF_PRIVATE *psf, MSADPCM_PRIVATE *pms)
{	unsigned int	blockindex ;
	unsigned char	byte ;
	int				chan, k, predict, bpred [2], idelta [2], errordelta, newsamp ;
	
	choose_predictor (pms->channels, pms->samples, bpred, idelta) ;

	/* Write the block header. */

	if (pms->channels == 1)
	{	pms->block [0]	= bpred [0] ;	
		pms->block [1]	= idelta [0] & 0xFF ;
		pms->block [2]	= idelta [0] >> 8 ;
		pms->block [3]	= pms->samples [1] & 0xFF ;
		pms->block [4]	= pms->samples [1] >> 8 ;
		pms->block [5]	= pms->samples [0] & 0xFF ;
		pms->block [6]	= pms->samples [0] >> 8 ;

		blockindex = 7 ;
		byte = 0 ;

		/* Encode the samples as 4 bit. */
		
		for (k = 2 ; k < pms->samplesperblock ; k++)
		{	predict = (pms->samples [k-1] * AdaptCoeff1 [bpred [0]] + pms->samples [k-2] * AdaptCoeff2 [bpred [0]]) >> 8 ;
			errordelta = (pms->samples [k] - predict) / idelta [0] ;
			if (errordelta < -8)
				errordelta = -8 ;
			else if (errordelta > 7)
				errordelta = 7 ;
			newsamp = predict + (idelta [0] * errordelta) ;
			if (newsamp > 32767)
				newsamp = 32767 ;
			else if (newsamp < -32768)
				newsamp = -32768 ;
			if (errordelta < 0)
				errordelta += 0x10 ;
				
			byte = (byte << 4) | (errordelta & 0xF) ;
			if (k % 2)
			{	pms->block [blockindex++] = byte ;
				byte = 0 ;
				} ;

			idelta [0] = (idelta [0] * AdaptationTable [errordelta]) >> 8 ;
			if (idelta [0] < 16)
				idelta [0] = 16 ;
			pms->samples [k] = newsamp ;
			} ;
		}
	else
	{	/* Stereo file. */
	
		pms->block [0]	= bpred [0] ;	
		pms->block [1]	= bpred [1] ;	

		pms->block [2]	= idelta [0] & 0xFF ;
		pms->block [3]	= idelta [0] >> 8 ;
		pms->block [4]	= idelta [1] & 0xFF ;
		pms->block [5]	= idelta [1] >> 8 ;
		
		pms->block [6]	= pms->samples [2] & 0xFF ;
		pms->block [7]	= pms->samples [2] >> 8 ;
		pms->block [8]	= pms->samples [3] & 0xFF ;
		pms->block [9]	= pms->samples [3] >> 8 ;

		pms->block [10]	= pms->samples [0] & 0xFF ;
		pms->block [11]	= pms->samples [0] >> 8 ;
		pms->block [12]	= pms->samples [1] & 0xFF ;
		pms->block [13]	= pms->samples [1] >> 8 ;
	
		blockindex = 14 ;
		byte = 0 ;
		chan = 1 ;
		
		for (k = 4 ; k < pms->samplesperblock ; k+=2)
		{	chan = chan ? 0 : 1 ;
			predict = (pms->samples [k-2] * AdaptCoeff1 [bpred [chan]] + pms->samples [k-4] * AdaptCoeff2 [bpred [chan]]) >> 8 ;
			errordelta = (pms->samples [k] - predict) / idelta [chan] ;
			if (errordelta < -8)
				errordelta = -8 ;
			else if (errordelta > 7)
				errordelta = 7 ;
			newsamp = predict + (idelta [chan] * errordelta) ;
			if (newsamp > 32767)
				newsamp = 32767 ;
			else if (newsamp < -32768)
				newsamp = -32768 ;
			if (errordelta < 0)
				errordelta += 0x10 ;
				
			byte = (byte << 4) | (errordelta & 0xF) ;
			if (k % 2)
			{	pms->block [blockindex++] = byte ;
				byte = 0 ;
				} ;

			idelta [chan] = (idelta [chan] * AdaptationTable [errordelta]) >> 8 ;
			if (idelta [chan] < 16)
				idelta [chan] = 16 ;
			pms->samples [k-2] = newsamp ;
			} ;
		} ;

	/* Write the block to disk. */

	if ((k = fwrite (pms->block, 1, pms->blocksize, psf->file)) != pms->blocksize)
		psf_log_printf (psf, "*** Warning : short write (%d != %d).\n", k, pms->blocksize) ;
		
	memset (pms->samples, 0, pms->samplesperblock * sizeof (short)) ;

	pms->blockcount ++ ;
	pms->samplecount = 0 ;
			
	return 1 ;
} /* msadpcm_write_block */

static int 
msadpcm_write (SF_PRIVATE *psf, MSADPCM_PRIVATE *pms, short *ptr, int len)
{	int		count, total = 0, index = 0 ;
	
	while (index < len)
	{	count = (pms->samplesperblock - pms->samplecount) * pms->channels ;

		if (count > len - index)
			count = len - index ;

		memcpy (&(pms->samples [pms->samplecount * pms->channels]), &(ptr [index]), count * sizeof (short)) ;
		index += count ;
		pms->samplecount += count / pms->channels ;
		total = index ;

		if (pms->samplecount >= pms->samplesperblock)
			msadpcm_write_block (psf, pms) ;	
		} ;

	return total ;		
} /* msadpcm_write */

static int		
msadpcm_write_s (SF_PRIVATE *psf, short *ptr, int len)
{	MSADPCM_PRIVATE *pms ; 
	int				total ;

	if (! psf->fdata)
		return 0 ;
	pms = (MSADPCM_PRIVATE*) psf->fdata ;
	
	total = msadpcm_write (psf, pms, ptr, len) ;

	return total ;
} /* msadpcm_write_s */

static int		
msadpcm_write_i  (SF_PRIVATE *psf, int *ptr, int len)
{	MSADPCM_PRIVATE *pms ; 
	short		*sptr ;
	int			k, bufferlen, writecount = 0, count ;
	int			index = 0, total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pms = (MSADPCM_PRIVATE*) psf->fdata ;
	
	sptr = (short*) psf->buffer ;
	bufferlen = ((SF_BUFFER_LEN / psf->blockwidth) * psf->blockwidth) / sizeof (short) ;
	while (len > 0)
	{	writecount = (len >= bufferlen) ? bufferlen : len ;
		for (k = 0 ; k < writecount ; k++)
			sptr [k] = (short) ptr [index+k] ;
		count = msadpcm_write (psf, pms, sptr, writecount) ;
		index += writecount ;
		total += count ;
		len -= writecount ;
		} ;
	return total ;
} /* msadpcm_write_i */

static int
msadpcm_write_f  (SF_PRIVATE *psf, float *ptr, int len)
{	MSADPCM_PRIVATE *pms ; 
	short		*sptr ;
	int			k, bufferlen, writecount = 0, count ;
	int			index = 0, total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pms = (MSADPCM_PRIVATE*) psf->fdata ;
	
	sptr = (short*) psf->buffer ;
	bufferlen = ((SF_BUFFER_LEN / psf->blockwidth) * psf->blockwidth) / sizeof (short) ;
	while (len > 0)
	{	writecount = (len >= bufferlen) ? bufferlen : len ;
		for (k = 0 ; k < writecount ; k++)
			sptr [k] = (short) (1.0 * ptr [index+k]) ;
		count = msadpcm_write (psf, pms, sptr, writecount) ;
		index += writecount ;
		total += count ;
		len -= writecount ;
		} ;
	return total ;
} /* msadpcm_write_f */

static int		
msadpcm_write_d  (SF_PRIVATE *psf, double *ptr, int len, int normalize)
{	MSADPCM_PRIVATE *pms ; 
	short		*sptr ;
	int			k, bufferlen, writecount = 0, count ;
	int			index = 0, total = 0 ;
	double 		normfact ;
	
	normfact = (normalize ? ((double) 0x8000) : 1.0) ;

	if (! psf->fdata)
		return 0 ;
	pms = (MSADPCM_PRIVATE*) psf->fdata ;
	
	sptr = (short*) psf->buffer ;
	bufferlen = ((SF_BUFFER_LEN / psf->blockwidth) * psf->blockwidth) / sizeof (short) ;
	while (len > 0)
	{	writecount = (len >= bufferlen) ? bufferlen : len ;
		for (k = 0 ; k < writecount ; k++)
			sptr [k] = (short) (normfact * ptr [index+k]) ;
		count = msadpcm_write (psf, pms, sptr, writecount) ;
		index += writecount ;
		total += count ;
		len -= writecount ;
		} ;
	return total ;
} /* msadpcm_write_d */

/*========================================================================================
*/

static int
msadpcm_write_header (SF_PRIVATE  *psf)
{	int  k, fmt_size, blockalign, samplesperblock, bytespersec, extrabytes ;

	blockalign      = srate2blocksize (psf->sf.samplerate) ;	
	samplesperblock = 2 + 2 * (blockalign - 7 * psf->sf.channels) / psf->sf.channels ;
	bytespersec     = (psf->sf.samplerate * blockalign) / samplesperblock ;
	
	/* Reset the current header length to zero. */
	psf->header [0] = 0 ;
	psf->headindex = 0 ;
	fseek (psf->file, 0, SEEK_SET) ;

	/* RIFF marker, length, WAVE and 'fmt ' markers. */		
	psf_binheader_writef (psf, "mlmm", RIFF_MARKER, psf->filelength - 8, WAVE_MARKER, fmt_MARKER) ;

	/* fmt chunk. */
	extrabytes = 2 + 2 + 7 * (2 + 2) ;
	fmt_size   = 2 + 2 + 4 + 4 + 2 + 2 + 2 + extrabytes ;
	
	/* fmt : size, WAV format type, channels. */
	psf_binheader_writef (psf, "lww", fmt_size, WAVE_FORMAT_MS_ADPCM, psf->sf.channels) ;

	/* fmt : samplerate, bytespersec. */
	psf_binheader_writef (psf, "ll", psf->sf.samplerate, bytespersec) ;

	/* fmt : blockalign, bitwidth, extrabytes, samplesperblock. */
	psf_binheader_writef (psf, "wwwww", blockalign, 4, extrabytes, samplesperblock, 7) ;
	
	for (k = 0 ; k < 7 ; k++)
		psf_binheader_writef (psf, "ww", AdaptCoeff1 [k], AdaptCoeff2 [k]) ;

	/* Fact chunk. */	
	psf_binheader_writef (psf, "mll", fact_MARKER, sizeof (int), psf->sf.samples) ;

	/* DATA chunk. */
	psf_binheader_writef (psf, "ml", data_MARKER, psf->datalength) ;

	fwrite (psf->header, psf->headindex, 1, psf->file) ;

	psf->dataoffset = psf->headindex ;

	psf->datalength  = (psf->sf.samples / samplesperblock) * samplesperblock ;
	if (psf->sf.samples % samplesperblock)
		psf->datalength += samplesperblock ;

	return 0 ;
} /* msadpcm_write_header */

static int	
msadpcm_close	(SF_PRIVATE  *psf)
{	MSADPCM_PRIVATE *pms ; 

	if (! psf->fdata)
		return 0 ;

	pms = (MSADPCM_PRIVATE*) psf->fdata ;

	if (psf->mode == SF_MODE_WRITE)
	{	/*  Now we know static int for certain the length of the file we can
		**  re-write the header.
		*/
		 
		if (pms->samplecount && pms->samplecount < pms->samplesperblock)
			msadpcm_write_block (psf, pms) ;	

		fseek (psf->file, 0, SEEK_END) ;
		psf->filelength = ftell (psf->file) ;

		psf->sf.samples = pms->samplesperblock * pms->blockcount ;
		psf->datalength = psf->filelength - psf->dataoffset ;

		msadpcm_write_header (psf) ;
		} ;

	if (psf->fdata)
		free (psf->fdata) ;
	psf->fdata = NULL ;

	return 0 ;
} /* msadpcm_close */

/*========================================================================================
** Static functions.
*/

static	unsigned int 
srate2blocksize (unsigned int srate)
{	if (srate < 12000)
		return 256 ;
	if (srate < 23000)
		return 512 ;
	return 1024 ;
} /* srate2blocksize */



/*----------------------------------------------------------------------------------------
**	Choosing the block predictor.
**	Each block requires a predictor and an idelta for each channel. 
**	The predictor is in the range [0..6] which is an index into the	two AdaptCoeff tables. 
**	The predictor is chosen by trying all of the possible predictors on a small set of
**	samples at the beginning of the block. The predictor with the smallest average
**	abs (idelta) is chosen as the best predictor for this block. 
**	The value of idelta is chosen to to give a 4 bit code value of +/- 4 (approx. half the 
**	max. code value). If the average abs (idelta) is zero, the sixth predictor is chosen.
**	If the value of idelta is less then 16 it is set to 16.
**
**	Microsoft uses an IDELTA_COUNT (number of sample pairs used to choose best predictor)
**	value of 3. The best possible results would be obtained by using all the samples to
**	choose the predictor.
*/

#define		IDELTA_COUNT	3

static	void	
choose_predictor (unsigned int channels, short *data, int *block_pred, int *idelta)
{	unsigned int	chan, k, bpred, idelta_sum, best_bpred, best_idelta ;
	
	for (chan = 0 ; chan < channels; chan++)
	{	best_bpred = best_idelta = 0 ;

		for (bpred = 0 ; bpred < 7 ; bpred++)
		{	idelta_sum = 0 ;
			for (k = 2 ; k < 2 + IDELTA_COUNT ; k++)
				idelta_sum += abs (data [k*channels] - ((data [(k-1)*channels] * AdaptCoeff1 [bpred] + data [(k-2)*channels] * AdaptCoeff2 [bpred]) >> 8)) ;
			idelta_sum /= (4 * IDELTA_COUNT) ;
			
			if (bpred == 0 || idelta_sum < best_idelta)
			{	best_bpred = bpred ;
				best_idelta = idelta_sum ;
				} ;
				
			if (! idelta_sum)
			{	best_bpred = bpred ;
				best_idelta = 16 ;
				break ;
				} ;
		
			} ; /* for bpred ... */
		if (best_idelta < 16)
			best_idelta = 16 ;
	
		block_pred [chan] = best_bpred ;
		idelta [chan]     = best_idelta ;
		} ;

	return ;
} /* choose_predictor */