adpcm.c

ADPCM 源码

/*
 * reconstruct()
 *
 * Returns reconstructed difference signal 'dq' obtained from
 * codeword 'i' and quantization step size scale factor 'y'.
 * Multiplication is performed in log base 2 domain as addition.
 */
int
reconstruct( sign, dqln, y )
	int		sign;	/* 0 for non-negative value */
	long	dqln;	/* G.72x codeword */
	int		y;	/* Step size multiplier */
{
	short		dql;	/* Log of 'dq' magnitude */
	short		dex;	/* Integer part of log */
	short		dqt;
	short		dq;	/* Reconstructed difference signal sample */

	dql = dqln + (y >> 2);	/* ADDA */

	if (dql < 0) {
		return ((sign) ? -0x8000 : 0);
	} else {		/* ANTILOG */
		dex = ((long)dql >> 7) & 15;
		dqt = 128 + (dql & 127);
		dq = ((long)dqt << 7) >> (14 - dex);
		return ((sign) ? (dq - 0x8000) : dq);
	}
}

/*
 * update()
 *
 * updates the state variables for each output code
 */
void
update( code_size, y, wi, fi, dq, sr, dqsez, state_ptr)
	int		code_size;	/* distinguish 723_40 with others */
	int		y;		/* quantizer step size */
	long		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		mant;	/* Adaptive predictor, FLOAT A */
	short		exp, mag;
	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;
	int 		aprin;

	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 + (long)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 + ((long)(wi - y) >> 5);

	/* LIMB */
	if (state_ptr->yu < 544)	/* 544 <=  <= 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) ?
			((long)exp << 6) + (((long)mag << 6) >> exp) :
			((long)exp << 6) + (((long)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] = ((long)exp << 6) + (((long)sr << 6) >> exp);
	} else if (sr > -32768) {
		mag = -sr;
		exp = quan(mag, power2, 15);
		state_ptr->sr[0] =  ((long)exp << 6) + (((long)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;
}

/*
 * Pack output codes into bytes and write them to stdout.
 * Returns 1 if there is residual output, else returns 0.
 */
int
pack_output( code, fpw )
	unsigned code;
	FILE	*fpw;
{
	static unsigned int	out_buffer = 0;
	static int		out_bits = 0;
	unsigned char		out_byte;


	out_buffer |= (code << out_bits);
	out_bits += 4;
	if (out_bits >= 8) {
		out_byte = out_buffer & 0xff;
		out_bits -= 8;
		out_buffer >>= 8;
		fwrite(&out_byte, sizeof (char), 1, fpw);
	}
	return (out_bits > 0);
}

int
unpack_input(code, fpr)
	unsigned char *code;
   FILE *fpr;
{
	static unsigned int	in_buffer = 0;
	static int		in_bits = 0;
	unsigned char		in_byte;

	if (in_bits < 4) {
		if (fread(&in_byte, sizeof (char), 1, fpr) != 1) {
			*code = 0;
			return (-1);
		}
		in_buffer |= (in_byte << in_bits);
		in_bits += 8;
	}
	*code = in_buffer & ((1 << 4) - 1);
	in_buffer >>= 4;
	in_bits -= 4;
	return (in_bits > 0);
}

main( argc, argv )
	int			argc;
	char			**argv;
{
	struct g72x_state	state_enc;
	struct g72x_state	state_dec;
	unsigned char	code;
	double		org;
	double		dec;
	double		dif;
	double		x;
	float		snr;
	short		sample;
	int		al;
	int		resid;
	int		in_size;
	int		count;
	short		in_buf;
	FILE		*fpr, *fpw1, *fpw2, *fpw3, *fopen();

	org = 0;
	dec = 0;

	if ((fpr = fopen(argv[1], "rb")) == NULL ) {
		fprintf(stderr, "Cannot open input_file : source\n");
//		fprintf(stderr, "Usage : adpcm sample_file dec_file > result\n");
	}

	if ((fpw1 = fopen(argv[2], "wb")) == NULL ) {
		fprintf(stderr, "Cannot open output_file : enc\n");
//		fprintf(stderr, "Usage : adpcm sample_file dec_file > result\n");
	}
   
	if ((fpw2 = fopen(argv[3], "wb")) == NULL ) {
		fprintf(stderr, "Cannot open output_file : dec\n");
//		fprintf(stderr, "Usage : adpcm sample_file dec_file > result\n");
	}

/*	if ((fpw3 = fopen(argv[4], "w")) == NULL ) {
		fprintf(stderr, "Cannot open output_file : out\n");
		fprintf(stderr, "Usage : adpcm sample_file dec_file > result\n");
	}
*/
	g72x_init_state(&state_enc);
	g72x_init_state(&state_dec);

	while (fread(&in_buf, sizeof(short), 1, fpr) == 1) {
		code = g721_encoder(in_buf, &state_enc, al, fpw3);
		resid = pack_output(code, fpw1);
		sample = g721_decoder(code, &state_dec, al);
		fwrite(&sample, sizeof(short), 1, fpw2);
		org += (double)in_buf*(double)in_buf;
		dif = in_buf - sample;
		dec += (double)dif*(double)dif;
//		printf("%d, %x, %d\n", in_buf, code, sample);
	}

	fclose(fpr);
	fclose(fpw1);
	fclose(fpw2);

	snr = 10*log10(org / dec);	// SNR=10*log10(org^2/(org-dec)^2)

	fclose(fpr);
	fclose(fpw1);
	fclose(fpw2);

	printf(" %s with org ADPCM : %lf\n", argv[1], snr);

	return 0;
}