g72x.c

symbian 系统下的g.723 g.723_24实现, 本源码在 series60 sdk fp2下调试通过

		dq = (dqt << 7) >> (14 - dex);
		return ((sign) ? (dq - 0x8000) : dq);
	}
}


/*
 * update()
 *
 * updates the state variables for each output code
 */
void
update(
	int		code_size,	/* distinguish 723_40 with others */
	int		y,		/* quantizer step size */
	int		wi,		/* scale factor multiplier */
	int		fi,		/* for long/short term energies */
	int		dq,		/* quantized prediction difference */
	int		sr,		/* reconstructed signal */
	int		dqsez,		/* difference from 2-pole predictor */
	struct g72x_state *state_ptr)	/* coder state pointer */
{
	int		cnt;
	short		mag, exp, mant;	/* Adaptive predictor, FLOAT A */
	short		a2p;		/* LIMC */
	short		a1ul;		/* UPA1 */
	short		ua2, pks1;	/* UPA2 */
	short		uga2a, fa1;
	short		uga2b;
	char		tr;		/* tone/transition detector */
	short		ylint, thr2, dqthr;
	short  		ylfrac, thr1;
	short		pk0;

	pk0 = (dqsez < 0) ? 1 : 0;	/* needed in updating predictor poles */

	mag = dq & 0x7FFF;		/* prediction difference magnitude */
	/* TRANS */
	ylint = state_ptr->yl >> 15;	/* exponent part of yl */
	ylfrac = (state_ptr->yl >> 10) & 0x1F;	/* fractional part of yl */
	thr1 = (32 + ylfrac) << ylint;		/* threshold */
	thr2 = (ylint > 9) ? 31 << 10 : thr1;	/* limit thr2 to 31 << 10 */
	dqthr = (thr2 + (thr2 >> 1)) >> 1;	/* dqthr = 0.75 * thr2 */
	if (state_ptr->td == 0)		/* signal supposed voice */
		tr = 0;
	else if (mag <= dqthr)		/* supposed data, but small mag */
		tr = 0;			/* treated as voice */
	else				/* signal is data (modem) */
		tr = 1;

	/*
	 * Quantizer scale factor adaptation.
	 */

	/* FUNCTW & FILTD & DELAY */
	/* update non-steady state step size multiplier */
	state_ptr->yu = y + ((wi - y) >> 5);

	/* LIMB */
	if (state_ptr->yu < 544)	/* 544 <= yu <= 5120 */
		state_ptr->yu = 544;
	else if (state_ptr->yu > 5120)
		state_ptr->yu = 5120;

	/* FILTE & DELAY */
	/* update steady state step size multiplier */
	state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);

	/*
	 * Adaptive predictor coefficients.
	 */
	if (tr == 1) {			/* reset a's and b's for modem signal */
		state_ptr->a[0] = 0;
		state_ptr->a[1] = 0;
		state_ptr->b[0] = 0;
		state_ptr->b[1] = 0;
		state_ptr->b[2] = 0;
		state_ptr->b[3] = 0;
		state_ptr->b[4] = 0;
		state_ptr->b[5] = 0;
	} else {			/* update a's and b's */
		pks1 = pk0 ^ state_ptr->pk[0];		/* UPA2 */

		/* update predictor pole a[1] */
		a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
		if (dqsez != 0) {
			fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
			if (fa1 < -8191)	/* a2p = function of fa1 */
				a2p -= 0x100;
			else if (fa1 > 8191)
				a2p += 0xFF;
			else
				a2p += fa1 >> 5;

			if (pk0 ^ state_ptr->pk[1])
				/* LIMC */
				if (a2p <= -12160)
					a2p = -12288;
				else if (a2p >= 12416)
					a2p = 12288;
				else
					a2p -= 0x80;
			else if (a2p <= -12416)
				a2p = -12288;
			else if (a2p >= 12160)
				a2p = 12288;
			else
				a2p += 0x80;
		}

		/* TRIGB & DELAY */
		state_ptr->a[1] = a2p;

		/* UPA1 */
		/* update predictor pole a[0] */
		state_ptr->a[0] -= state_ptr->a[0] >> 8;
		if (dqsez != 0)
			if (pks1 == 0)
				state_ptr->a[0] += 192;
			else
				state_ptr->a[0] -= 192;

		/* LIMD */
		a1ul = 15360 - a2p;
		if (state_ptr->a[0] < -a1ul)
			state_ptr->a[0] = -a1ul;
		else if (state_ptr->a[0] > a1ul)
			state_ptr->a[0] = a1ul;

		/* UPB : update predictor zeros b[6] */
		for (cnt = 0; cnt < 6; cnt++) {
			if (code_size == 5)		/* for 40Kbps G.723 */
				state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
			else			/* for G.721 and 24Kbps G.723 */
				state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
			if (dq & 0x7FFF) {			/* XOR */
				if ((dq ^ state_ptr->dq[cnt]) >= 0)
					state_ptr->b[cnt] += 128;
				else
					state_ptr->b[cnt] -= 128;
			}
		}
	}

	for (cnt = 5; cnt > 0; cnt--)
		state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
	/* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
	if (mag == 0) {
		state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
	} else {
		exp = quan(mag, power2, 15);
		state_ptr->dq[0] = (dq >= 0) ?
		    (exp << 6) + ((mag << 6) >> exp) :
		    (exp << 6) + ((mag << 6) >> exp) - 0x400;
	}

	state_ptr->sr[1] = state_ptr->sr[0];
	/* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
	if (sr == 0) {
		state_ptr->sr[0] = 0x20;
	} else if (sr > 0) {
		exp = quan(sr, power2, 15);
		state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
	} else if (sr > -32768) {
		mag = -sr;
		exp = quan(mag, power2, 15);
		state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
	} else
		state_ptr->sr[0] = 0xFC20;

	/* DELAY A */
	state_ptr->pk[1] = state_ptr->pk[0];
	state_ptr->pk[0] = pk0;

	/* TONE */
	if (tr == 1)		/* this sample has been treated as data */
		state_ptr->td = 0;	/* next one will be treated as voice */
	else if (a2p < -11776)	/* small sample-to-sample correlation */
		state_ptr->td = 1;	/* signal may be data */
	else				/* signal is voice */
		state_ptr->td = 0;

	/*
	 * Adaptation speed control.
	 */
	state_ptr->dms += (fi - state_ptr->dms) >> 5;		/* FILTA */
	state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);	/* FILTB */

	if (tr == 1)
		state_ptr->ap = 256;
	else if (y < 1536)					/* SUBTC */
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else if (state_ptr->td == 1)
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
	    (state_ptr->dml >> 3))
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else
		state_ptr->ap += (-state_ptr->ap) >> 4;
}

/*
 * tandem_adjust(sr, se, y, i, sign)
 *
 * At the end of ADPCM decoding, it simulates an encoder which may be receiving
 * the output of this decoder as a tandem process. If the output of the
 * simulated encoder differs from the input to this decoder, the decoder output
 * is adjusted by one level of A-law or u-law codes.
 *
 * Input:
 *	sr	decoder output linear PCM sample,
 *	se	predictor estimate sample,
 *	y	quantizer step size,
 *	i	decoder input code,
 *	sign	sign bit of code i
 *
 * Return:
 *	adjusted A-law or u-law compressed sample.
 */
int
tandem_adjust_alaw(
	int		sr,	/* decoder output linear PCM sample */
	int		se,	/* predictor estimate sample */
	int		y,	/* quantizer step size */
	int		i,	/* decoder input code */
	int		sign,
	short		*qtab)
{
	unsigned char	sp;	/* A-law compressed 8-bit code */
	short		dx;	/* prediction error */
	char		id;	/* quantized prediction error */
	int		sd;	/* adjusted A-law decoded sample value */
	int		im;	/* biased magnitude of i */
	int		imx;	/* biased magnitude of id */

	if (sr <= -32768)
		sr = -1;
	sp = linear2alaw((sr >> 1) << 3);	/* short to A-law compression */
	dx = (alaw2linear(sp) >> 2) - se;	/* 16-bit prediction error */
	id = quantize(dx, y, qtab, sign - 1);

	if (id == i) {			/* no adjustment on sp */
		return (sp);
	} else {			/* sp adjustment needed */
		/* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
		im = i ^ sign;		/* 2's complement to biased unsigned */
		imx = id ^ sign;

		if (imx > im) {		/* sp adjusted to next lower value */
			if (sp & 0x80) {
				sd = (sp == 0xD5) ? 0x55 :
				    ((sp ^ 0x55) - 1) ^ 0x55;
			} else {
				sd = (sp == 0x2A) ? 0x2A :
				    ((sp ^ 0x55) + 1) ^ 0x55;
			}
		} else {		/* sp adjusted to next higher value */
			if (sp & 0x80)
				sd = (sp == 0xAA) ? 0xAA :
				    ((sp ^ 0x55) + 1) ^ 0x55;
			else
				sd = (sp == 0x55) ? 0xD5 :
				    ((sp ^ 0x55) - 1) ^ 0x55;
		}
		return (sd);
	}
}

int
tandem_adjust_ulaw(
	int		sr,	/* decoder output linear PCM sample */
	int		se,	/* predictor estimate sample */
	int		y,	/* quantizer step size */
	int		i,	/* decoder input code */
	int		sign,
	short		*qtab)
{
	unsigned char	sp;	/* u-law compressed 8-bit code */
	short		dx;	/* prediction error */
	char		id;	/* quantized prediction error */
	int		sd;	/* adjusted u-law decoded sample value */
	int		im;	/* biased magnitude of i */
	int		imx;	/* biased magnitude of id */

	if (sr <= -32768)
		sr = 0;
	sp = linear2ulaw(sr << 2);	/* short to u-law compression */
	dx = (ulaw2linear(sp) >> 2) - se;	/* 16-bit prediction error */
	id = quantize(dx, y, qtab, sign - 1);
	if (id == i) {
		return (sp);
	} else {
		/* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
		im = i ^ sign;		/* 2's complement to biased unsigned */
		imx = id ^ sign;
		if (imx > im) {		/* sp adjusted to next lower value */
			if (sp & 0x80)
				sd = (sp == 0xFF) ? 0x7E : sp + 1;
			else
				sd = (sp == 0) ? 0 : sp - 1;

		} else {		/* sp adjusted to next higher value */
			if (sp & 0x80)
				sd = (sp == 0x80) ? 0x80 : sp - 1;
			else
				sd = (sp == 0x7F) ? 0xFE : sp + 1;
		}
		return (sd);
	}
}