sbrhuff.c

nds上大名鼎鼎的DSOrganize 2.8最新源代码。很值得研究。

 * Outputs:     dequantized env scalefactors for left channel (before decoupling)
 *              dequantized env scalefactors for right channel (if coupling off)
 *                or raw decoded env scalefactors for right channel (if coupling on)
 *
 * Return:      none
 **************************************************************************************/
void DecodeSBREnvelope(BitStreamInfo *bsi, PSInfoSBR *psi, SBRGrid *sbrGrid, SBRFreq *sbrFreq, SBRChan *sbrChan, int ch)
{
	int huffIndexTime, huffIndexFreq, env, envStartBits, band, nBands, sf, lastEnv;
	int freqRes, freqResPrev, dShift, i;

	if (psi->couplingFlag && ch) {
		dShift = 1;
		if (sbrGrid->ampResFrame) {
			huffIndexTime = HuffTabSBR_tEnv30b;
			huffIndexFreq = HuffTabSBR_fEnv30b;
			envStartBits = 5;
		} else {
			huffIndexTime = HuffTabSBR_tEnv15b;
			huffIndexFreq = HuffTabSBR_fEnv15b;
			envStartBits = 6;
		}
	} else {
		dShift = 0;
		if (sbrGrid->ampResFrame) {
			huffIndexTime = HuffTabSBR_tEnv30;
			huffIndexFreq = HuffTabSBR_fEnv30;
			envStartBits = 6;
		} else {
			huffIndexTime = HuffTabSBR_tEnv15;
			huffIndexFreq = HuffTabSBR_fEnv15;
			envStartBits = 7;
		}
	}

	/* range of envDataQuant[] = [0, 127] (see comments in DequantizeEnvelope() for reference) */
	for (env = 0; env < sbrGrid->numEnv; env++) {
		nBands =      (sbrGrid->freqRes[env] ? sbrFreq->nHigh : sbrFreq->nLow);
		freqRes =     (sbrGrid->freqRes[env]);
		freqResPrev = (env == 0 ? sbrGrid->freqResPrev : sbrGrid->freqRes[env-1]);
		lastEnv =     (env == 0 ? sbrGrid->numEnvPrev-1 : env-1);
		if (lastEnv < 0)
			lastEnv = 0;	/* first frame */

		ASSERT(nBands <= MAX_QMF_BANDS);

		if (sbrChan->deltaFlagEnv[env] == 0) {
			/* delta coding in freq */
			sf = GetBits(bsi, envStartBits) << dShift;
			sbrChan->envDataQuant[env][0] = sf;
			for (band = 1; band < nBands; band++) {
				sf = DecodeOneSymbol(bsi, huffIndexFreq) << dShift;
				sbrChan->envDataQuant[env][band] = sf + sbrChan->envDataQuant[env][band-1];
			}
		} else if (freqRes == freqResPrev) {
			/* delta coding in time - same freq resolution for both frames */
			for (band = 0; band < nBands; band++) {
				sf = DecodeOneSymbol(bsi, huffIndexTime) << dShift;
				sbrChan->envDataQuant[env][band] = sf + sbrChan->envDataQuant[lastEnv][band];
			}
		} else if (freqRes == 0 && freqResPrev == 1) {
			/* delta coding in time - low freq resolution for new frame, high freq resolution for old frame */
			for (band = 0; band < nBands; band++) {
				sf = DecodeOneSymbol(bsi, huffIndexTime) << dShift;
				sbrChan->envDataQuant[env][band] = sf;
				for (i = 0; i < sbrFreq->nHigh; i++) {
					if (sbrFreq->freqHigh[i] == sbrFreq->freqLow[band]) {
						sbrChan->envDataQuant[env][band] += sbrChan->envDataQuant[lastEnv][i];
						break;
					}
				}
			}
		} else if (freqRes == 1 && freqResPrev == 0) {
			/* delta coding in time - high freq resolution for new frame, low freq resolution for old frame */
			for (band = 0; band < nBands; band++) {
				sf = DecodeOneSymbol(bsi, huffIndexTime) << dShift;
				sbrChan->envDataQuant[env][band] = sf;
				for (i = 0; i < sbrFreq->nLow; i++) {
					if (sbrFreq->freqLow[i] <= sbrFreq->freqHigh[band] && sbrFreq->freqHigh[band] < sbrFreq->freqLow[i+1] ) {
						sbrChan->envDataQuant[env][band] += sbrChan->envDataQuant[lastEnv][i];
						break;
					}
				}
			}
		}

		/* skip coupling channel */
		if (ch != 1 || psi->couplingFlag != 1)
			psi->envDataDequantScale[ch][env] = DequantizeEnvelope(nBands, sbrGrid->ampResFrame, sbrChan->envDataQuant[env], psi->envDataDequant[ch][env]);
	}
	sbrGrid->numEnvPrev = sbrGrid->numEnv;
	sbrGrid->freqResPrev = sbrGrid->freqRes[sbrGrid->numEnv-1];
}

/**************************************************************************************
 * Function:    DecodeSBRNoise
 *
 * Description: decode delta Huffman coded noise scalefactors from bitstream
 *
 * Inputs:      BitStreamInfo struct pointing to start of noise data
 *              initialized PSInfoSBR struct
 *              initialized SBRGrid struct for this channel
 *              initialized SBRFreq struct for this SCE/CPE block
 *              initialized SBRChan struct for this channel
 *              index of current channel (0 for SCE, 0 or 1 for CPE)
 * 
 * Outputs:     dequantized noise scalefactors for left channel (before decoupling)
 *              dequantized noise scalefactors for right channel (if coupling off)
 *                or raw decoded noise scalefactors for right channel (if coupling on)
 *
 * Return:      none
 **************************************************************************************/
void DecodeSBRNoise(BitStreamInfo *bsi, PSInfoSBR *psi, SBRGrid *sbrGrid, SBRFreq *sbrFreq, SBRChan *sbrChan, int ch)
{
	int huffIndexTime, huffIndexFreq, noiseFloor, band, dShift, sf, lastNoiseFloor;

	if (psi->couplingFlag && ch) {
		dShift = 1;
		huffIndexTime = HuffTabSBR_tNoise30b;
		huffIndexFreq = HuffTabSBR_fNoise30b;
	} else {
		dShift = 0;
		huffIndexTime = HuffTabSBR_tNoise30;
		huffIndexFreq = HuffTabSBR_fNoise30;
	}

	for (noiseFloor = 0; noiseFloor < sbrGrid->numNoiseFloors; noiseFloor++) {
		lastNoiseFloor = (noiseFloor == 0 ? sbrGrid->numNoiseFloorsPrev-1 : noiseFloor-1);
		if (lastNoiseFloor < 0)
			lastNoiseFloor = 0;	/* first frame */

		ASSERT(sbrFreq->numNoiseFloorBands <= MAX_QMF_BANDS);

		if (sbrChan->deltaFlagNoise[noiseFloor] == 0) {
			/* delta coding in freq */
			sbrChan->noiseDataQuant[noiseFloor][0] = GetBits(bsi, 5) << dShift;
			for (band = 1; band < sbrFreq->numNoiseFloorBands; band++) {
				sf = DecodeOneSymbol(bsi, huffIndexFreq) << dShift;
				sbrChan->noiseDataQuant[noiseFloor][band] = sf + sbrChan->noiseDataQuant[noiseFloor][band-1];
			}
		} else {
			/* delta coding in time */
			for (band = 0; band < sbrFreq->numNoiseFloorBands; band++) {
				sf = DecodeOneSymbol(bsi, huffIndexTime) << dShift;
				sbrChan->noiseDataQuant[noiseFloor][band] = sf + sbrChan->noiseDataQuant[lastNoiseFloor][band];
			}
		}

		/* skip coupling channel */
		if (ch != 1 || psi->couplingFlag != 1)
			DequantizeNoise(sbrFreq->numNoiseFloorBands, sbrChan->noiseDataQuant[noiseFloor], psi->noiseDataDequant[ch][noiseFloor]);
	}
	sbrGrid->numNoiseFloorsPrev = sbrGrid->numNoiseFloors;
}

/* dqTabCouple[i] = 2 / (1 + 2^(12 - i)), format = Q30 */
static const int dqTabCouple[25] = {
	0x0007ff80, 0x000ffe00, 0x001ff802, 0x003fe010, 0x007f8080, 0x00fe03f8, 0x01f81f82, 0x03e0f83e, 
	0x07878788, 0x0e38e38e, 0x1999999a, 0x2aaaaaab, 0x40000000, 0x55555555, 0x66666666, 0x71c71c72, 
	0x78787878, 0x7c1f07c2, 0x7e07e07e, 0x7f01fc08, 0x7f807f80, 0x7fc01ff0, 0x7fe007fe, 0x7ff00200, 
	0x7ff80080, 
};

/**************************************************************************************
 * Function:    UncoupleSBREnvelope
 *
 * Description: scale dequantized envelope scalefactors according to channel 
 *                coupling rules
 *
 * Inputs:      initialized PSInfoSBR struct including
 *                dequantized envelope data for left channel
 *              initialized SBRGrid struct for this channel
 *              initialized SBRFreq struct for this SCE/CPE block
 *              initialized SBRChan struct for right channel including
 *                quantized envelope scalefactors
 * 
 * Outputs:     dequantized envelope data for left channel (after decoupling)
 *              dequantized envelope data for right channel (after decoupling)
 *
 * Return:      none
 **************************************************************************************/
void UncoupleSBREnvelope(PSInfoSBR *psi, SBRGrid *sbrGrid, SBRFreq *sbrFreq, SBRChan *sbrChanR)
{
	int env, band, nBands, scalei, E_1;

	scalei = (sbrGrid->ampResFrame ? 0 : 1);
	for (env = 0; env < sbrGrid->numEnv; env++) {
		nBands = (sbrGrid->freqRes[env] ? sbrFreq->nHigh : sbrFreq->nLow);
		psi->envDataDequantScale[1][env] = psi->envDataDequantScale[0][env]; /* same scalefactor for L and R */
		for (band = 0; band < nBands; band++) {
			/* clip E_1 to [0, 24] (scalefactors approach 0 or 2) */
			E_1 = sbrChanR->envDataQuant[env][band] >> scalei;
			if (E_1 < 0)	E_1 = 0;
			if (E_1 > 24)	E_1 = 24;

			/* envDataDequant[0] has 1 GB, so << by 2 is okay */
			psi->envDataDequant[1][env][band] = MULSHIFT32(psi->envDataDequant[0][env][band], dqTabCouple[24 - E_1]) << 2;
			psi->envDataDequant[0][env][band] = MULSHIFT32(psi->envDataDequant[0][env][band], dqTabCouple[E_1]) << 2;
		}
	}
}

/**************************************************************************************
 * Function:    UncoupleSBRNoise
 *
 * Description: scale dequantized noise floor scalefactors according to channel 
 *                coupling rules
 *
 * Inputs:      initialized PSInfoSBR struct including
 *                dequantized noise data for left channel
 *              initialized SBRGrid struct for this channel
 *              initialized SBRFreq struct for this SCE/CPE block
 *              initialized SBRChan struct for this channel including
 *                quantized noise scalefactors
 * 
 * Outputs:     dequantized noise data for left channel (after decoupling)
 *              dequantized noise data for right channel (after decoupling)
 *
 * Return:      none
 **************************************************************************************/
void UncoupleSBRNoise(PSInfoSBR *psi, SBRGrid *sbrGrid, SBRFreq *sbrFreq, SBRChan *sbrChanR)
{
	int noiseFloor, band, Q_1;
	
	for (noiseFloor = 0; noiseFloor < sbrGrid->numNoiseFloors; noiseFloor++) {
		for (band = 0; band < sbrFreq->numNoiseFloorBands; band++) {
			/* Q_1 should be in range [0, 24] according to 4.6.18.3.6, but check to make sure */
			Q_1 = sbrChanR->noiseDataQuant[noiseFloor][band];
			if (Q_1 < 0)	Q_1 = 0;
			if (Q_1 > 24)	Q_1 = 24;

			/* noiseDataDequant[0] has 1 GB, so << by 2 is okay */
			psi->noiseDataDequant[1][noiseFloor][band] = MULSHIFT32(psi->noiseDataDequant[0][noiseFloor][band], dqTabCouple[24 - Q_1]) << 2;
			psi->noiseDataDequant[0][noiseFloor][band] = MULSHIFT32(psi->noiseDataDequant[0][noiseFloor][band], dqTabCouple[Q_1]) << 2;
		}
	}
}