noiseless.c

MP3 for ARM codec. [asm+C]

 * Outputs:     updated PulseInfo struct
 *
 * Return:      none
 **************************************************************************************/
static void DecodePulseInfo(BitStreamInfo *bsi, PulseInfo *pi)
{
	int i;

	pi->numPulse = GetBits(bsi, 2) + 1;		/* add 1 here */
	pi->startSFB = GetBits(bsi, 6);
	for (i = 0; i < pi->numPulse; i++) {
		pi->offset[i] = GetBits(bsi, 5);
		pi->amp[i] = GetBits(bsi, 4);
	}
}

/**************************************************************************************
 * Function:    DecodeTNSInfo
 *
 * Description: decode TNS filter information
 *
 * Inputs:      BitStreamInfo struct pointing to start of TNS info
 *                (14496-3, table 4.4.27)
 *              window sequence (short or long blocks)
 *
 * Outputs:     updated TNSInfo struct
 *              buffer of decoded (signed) TNS filter coefficients
 *
 * Return:      none
 **************************************************************************************/
static void DecodeTNSInfo(BitStreamInfo *bsi, int winSequence, TNSInfo *ti, signed char *tnsCoef)
{
	int i, w, f, coefBits, compress;
	signed char c, s, n;
	signed char sgnMask[3] = { 0x02,  0x04,  0x08};
	signed char negMask[3] = {~0x03, ~0x07, ~0x0f};
	unsigned char *filtLength, *filtOrder, *filtDir;

	filtLength = ti->length;
	filtOrder =  ti->order;
	filtDir =    ti->dir;

	if (winSequence == 2) {
		/* short blocks */
		for (w = 0; w < NWINDOWS_SHORT; w++) {
			ti->numFilt[w] = GetBits(bsi, 1);
			if (ti->numFilt[w]) {
				ti->coefRes[w] = GetBits(bsi, 1) + 3;
				*filtLength =    GetBits(bsi, 4);
				*filtOrder =     GetBits(bsi, 3);
				if (*filtOrder) {
					*filtDir++ =      GetBits(bsi, 1);
					compress =        GetBits(bsi, 1);
					coefBits = (int)ti->coefRes[w] - compress;	/* 2, 3, or 4 */
					s = sgnMask[coefBits - 2];
					n = negMask[coefBits - 2];
					for (i = 0; i < *filtOrder; i++) {
						c = GetBits(bsi, coefBits);
						if (c & s)	c |= n;
						*tnsCoef++ = c;
					}
				}
				filtLength++;
				filtOrder++;
			}
		}
	} else {
		/* long blocks */
		ti->numFilt[0] = GetBits(bsi, 2);
		if (ti->numFilt[0])
			ti->coefRes[0] = GetBits(bsi, 1) + 3;
		for (f = 0; f < ti->numFilt[0]; f++) {
			*filtLength =      GetBits(bsi, 6);
			*filtOrder =       GetBits(bsi, 5);
			if (*filtOrder) {
				*filtDir++ =     GetBits(bsi, 1);
				compress =       GetBits(bsi, 1);
				coefBits = (int)ti->coefRes[0] - compress;	/* 2, 3, or 4 */
				s = sgnMask[coefBits - 2];
				n = negMask[coefBits - 2];
				for (i = 0; i < *filtOrder; i++) {
					c = GetBits(bsi, coefBits);
					if (c & s)	c |= n;
					*tnsCoef++ = c;
				}
			}
			filtLength++;
			filtOrder++;
		}
	}
}

/* bitstream field lengths for gain control data:
 *   gainBits[winSequence][0] = maxWindow (how many gain windows there are)
 *   gainBits[winSequence][1] = locBitsZero (bits for alocCode if window == 0)
 *   gainBits[winSequence][2] = locBits (bits for alocCode if window != 0)
 */
static const unsigned char gainBits[4][3] = {
	{1, 5, 5},  /* long */
	{2, 4, 2},  /* start */
	{8, 2, 2},  /* short */
	{2, 4, 5},  /* stop */
};

/**************************************************************************************
 * Function:    DecodeGainControlInfo
 *
 * Description: decode gain control information (SSR profile only)
 *
 * Inputs:      BitStreamInfo struct pointing to start of gain control info
 *                (14496-3, table 4.4.12)
 *              window sequence (short or long blocks)
 *
 * Outputs:     updated GainControlInfo struct
 *
 * Return:      none
 **************************************************************************************/
static void DecodeGainControlInfo(BitStreamInfo *bsi, int winSequence, GainControlInfo *gi)
{
	int bd, wd, ad;
	int locBits, locBitsZero, maxWin;
	
	gi->maxBand = GetBits(bsi, 2);
	maxWin =      (int)gainBits[winSequence][0];
	locBitsZero = (int)gainBits[winSequence][1];
	locBits =     (int)gainBits[winSequence][2];

	for (bd = 1; bd <= gi->maxBand; bd++) {
		for (wd = 0; wd < maxWin; wd++) {
			gi->adjNum[bd][wd] = GetBits(bsi, 3);
			for (ad = 0; ad < gi->adjNum[bd][wd]; ad++) {
				gi->alevCode[bd][wd][ad] = GetBits(bsi, 4);
				gi->alocCode[bd][wd][ad] = GetBits(bsi, (wd == 0 ? locBitsZero : locBits));
			}
		}
	}
}

/**************************************************************************************
 * Function:    DecodeICS
 *
 * Description: decode individual channel stream
 *
 * Inputs:      platform specific info struct
 *              BitStreamInfo struct pointing to start of individual channel stream
 *                (14496-3, table 4.4.24) 
 *              index of current channel
 *
 * Outputs:     updated section data, scale factor data, pulse data, TNS data, 
 *                and gain control data
 *
 * Return:      none
 **************************************************************************************/
static void DecodeICS(PSInfoBase *psi, BitStreamInfo *bsi, int ch)
{
	int globalGain;
	ICSInfo *icsInfo;
	PulseInfo *pi;
	TNSInfo *ti;
	GainControlInfo *gi;

	icsInfo = (ch == 1 && psi->commonWin == 1) ? &(psi->icsInfo[0]) : &(psi->icsInfo[ch]);

	globalGain = GetBits(bsi, 8);
	if (!psi->commonWin)
		DecodeICSInfo(bsi, icsInfo, psi->sampRateIdx);

	DecodeSectionData(bsi, icsInfo->winSequence, icsInfo->numWinGroup, icsInfo->maxSFB, psi->sfbCodeBook[ch]);

	DecodeScaleFactors(bsi, icsInfo->numWinGroup, icsInfo->maxSFB, globalGain, psi->sfbCodeBook[ch], psi->scaleFactors[ch]);
	
	pi = &psi->pulseInfo[ch];
	pi->pulseDataPresent = GetBits(bsi, 1);
	if (pi->pulseDataPresent)
		DecodePulseInfo(bsi, pi);

	ti = &psi->tnsInfo[ch];
	ti->tnsDataPresent = GetBits(bsi, 1);
	if (ti->tnsDataPresent)
		DecodeTNSInfo(bsi, icsInfo->winSequence, ti, ti->coef);

	gi = &psi->gainControlInfo[ch];
	gi->gainControlDataPresent = GetBits(bsi, 1);
	if (gi->gainControlDataPresent)
		DecodeGainControlInfo(bsi, icsInfo->winSequence, gi);
}

/**************************************************************************************
 * Function:    DecodeNoiselessData
 *
 * Description: decode noiseless data (side info and transform coefficients)
 *
 * Inputs:      valid AACDecInfo struct
 *              double pointer to buffer pointing to start of individual channel stream
 *                (14496-3, table 4.4.24)
 *              pointer to bit offset
 *              pointer to number of valid bits remaining in buf
 *              index of current channel
 *
 * Outputs:     updated global gain, section data, scale factor data, pulse data,
 *                TNS data, gain control data, and spectral data
 *
 * Return:      0 if successful, error code (< 0) if error
 **************************************************************************************/
int DecodeNoiselessData(AACDecInfo *aacDecInfo, unsigned char **buf, int *bitOffset, int *bitsAvail, int ch)
{
	int bitsUsed;
	BitStreamInfo bsi;
	PSInfoBase *psi;
	ICSInfo *icsInfo;

	/* validate pointers */
	if (!aacDecInfo || !aacDecInfo->psInfoBase)
		return ERR_AAC_NULL_POINTER;
	psi = (PSInfoBase *)(aacDecInfo->psInfoBase);
	icsInfo = (ch == 1 && psi->commonWin == 1) ? &(psi->icsInfo[0]) : &(psi->icsInfo[ch]);
	
	SetBitstreamPointer(&bsi, (*bitsAvail+7) >> 3, *buf);
	GetBits(&bsi, *bitOffset);

	DecodeICS(psi, &bsi, ch);

	if (icsInfo->winSequence == 2)
		DecodeSpectrumShort(psi, &bsi, ch);
	else
		DecodeSpectrumLong(psi, &bsi, ch);

	bitsUsed = CalcBitsUsed(&bsi, *buf, *bitOffset);
	*buf += ((bitsUsed + *bitOffset) >> 3);
	*bitOffset = ((bitsUsed + *bitOffset) & 0x07);
	*bitsAvail -= bitsUsed;

	aacDecInfo->sbDeinterleaveReqd[ch] = 0;
	aacDecInfo->tnsUsed |= psi->tnsInfo[ch].tnsDataPresent;	/* set flag if TNS used for any channel */

	return ERR_AAC_NONE;
}