parse.c

这是著名的TCPMP播放器在WINDWOWS,和WINCE下编译通过的源程序.笔者对其中的LIBMAD库做了针对ARM MPU的优化. 并增加了词幕功能.

/*
 * parse.c
 * Copyright (C) 2000-2003 Michel Lespinasse <[e-mail]>
 * Copyright (C) 1999-2000 Aaron Holtzman <[e-mail]>
 *
 * This file is part of a52dec, a free ATSC A-52 stream decoder.
 * See http://liba52.sourceforge.net/ for updates.
 *
 * a52dec is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * a52dec is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include "a52.h"
#include "a52_internal.h"
#include "bitstream.h"
#include "tables.h"

#if defined(HAVE_MEMALIGN) && !defined(__cplusplus)
/* some systems have memalign() but no declaration for it */
void * memalign (size_t align, size_t size);
#else
/* assume malloc alignment is sufficient */
#define memalign(align,size) malloc (size)
#endif

typedef struct {
    quantizer_t q1[2];
    quantizer_t q2[2];
    quantizer_t q4;
    int q1_ptr;
    int q2_ptr;
    int q4_ptr;
} quantizer_set_t;

static uint8_t halfrate[12] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3};

a52_state_t * a52_init (uint32_t mm_accel)
{
    a52_state_t * state;
    int i;

    state = (a52_state_t *) malloc (sizeof (a52_state_t));
    if (state == NULL)
	return NULL;

    state->samples = (sample_t *) memalign (16, 256 * 12 * sizeof (sample_t));
    if (state->samples == NULL) {
	free (state);
	return NULL;
    }

    for (i = 0; i < 256 * 12; i++)
	state->samples[i] = 0;

    state->downmixed = 1;

    state->lfsr_state = 1;

    a52_imdct_init (mm_accel);

    return state;
}

sample_t * a52_samples (a52_state_t * state)
{
    return state->samples;
}

int a52_syncinfo (uint8_t * buf, int * flags,
		  int * sample_rate, int * bit_rate)
{
    static int rate[] = { 32,  40,  48,  56,  64,  80,  96, 112,
			 128, 160, 192, 224, 256, 320, 384, 448,
			 512, 576, 640};
    static uint8_t lfeon[8] = {0x10, 0x10, 0x04, 0x04, 0x04, 0x01, 0x04, 0x01};
    int frmsizecod;
    int bitrate;
    int half;
    int acmod;

    if ((buf[0] != 0x0b) || (buf[1] != 0x77))	/* syncword */
	return 0;

    if (buf[5] >= 0x60)		/* bsid >= 12 */
	return 0;
    half = halfrate[buf[5] >> 3];

    /* acmod, dsurmod and lfeon */
    acmod = buf[6] >> 5;
    *flags = ((((buf[6] & 0xf8) == 0x50) ? A52_DOLBY : acmod) |
	      ((buf[6] & lfeon[acmod]) ? A52_LFE : 0));

    frmsizecod = buf[4] & 63;
    if (frmsizecod >= 38)
	return 0;
    bitrate = rate [frmsizecod >> 1];
    *bit_rate = (bitrate * 1000) >> half;

    switch (buf[4] & 0xc0) {
    case 0:
	*sample_rate = 48000 >> half;
	return 4 * bitrate;
    case 0x40:
	*sample_rate = 44100 >> half;
	return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
    case 0x80:
	*sample_rate = 32000 >> half;
	return 6 * bitrate;
    default:
	return 0;
    }
}

int a52_frame (a52_state_t * state, uint8_t * buf, int * flags,
	       level_t * level, sample_t bias)
{
    static level_t clev[4] = { LEVEL (LEVEL_3DB), LEVEL (LEVEL_45DB),
			       LEVEL (LEVEL_6DB), LEVEL (LEVEL_45DB) };
    static level_t slev[4] = { LEVEL (LEVEL_3DB), LEVEL (LEVEL_6DB), 
			       0,                 LEVEL (LEVEL_6DB) };
    int chaninfo;
    int acmod;

    state->fscod = buf[4] >> 6;
    state->halfrate = halfrate[buf[5] >> 3];
    state->acmod = acmod = buf[6] >> 5;

    a52_bitstream_set_ptr (state, buf + 6);
    bitstream_get (state, 3);	/* skip acmod we already parsed */

    if ((acmod == 2) && (bitstream_get (state, 2) == 2))	/* dsurmod */
	acmod = A52_DOLBY;

    state->clev = state->slev = 0;

    if ((acmod & 1) && (acmod != 1))
	state->clev = clev[bitstream_get (state, 2)];	/* cmixlev */

    if (acmod & 4)
	state->slev = slev[bitstream_get (state, 2)];	/* surmixlev */

    state->lfeon = bitstream_get (state, 1);

    state->output = a52_downmix_init (acmod, *flags, level,
				      state->clev, state->slev);
    if (state->output < 0)
	return 1;
    if (state->lfeon && (*flags & A52_LFE))
	state->output |= A52_LFE;
    *flags = state->output;
    /* the 2* compensates for differences in imdct */
    state->dynrng = state->level = MUL_C (*level, 2);
    state->bias = bias;
    state->dynrnge = 1;
    state->dynrngcall = NULL;
    state->cplba.deltbae = DELTA_BIT_NONE;
    state->ba[0].deltbae = state->ba[1].deltbae = state->ba[2].deltbae =
	state->ba[3].deltbae = state->ba[4].deltbae = DELTA_BIT_NONE;

    chaninfo = !acmod;
    do {
	bitstream_get (state, 5);	/* dialnorm */
	if (bitstream_get (state, 1))	/* compre */
	    bitstream_get (state, 8);	/* compr */
	if (bitstream_get (state, 1))	/* langcode */
	    bitstream_get (state, 8);	/* langcod */
	if (bitstream_get (state, 1))	/* audprodie */
	    bitstream_get (state, 7);	/* mixlevel + roomtyp */
    } while (chaninfo--);

    bitstream_get (state, 2);		/* copyrightb + origbs */

    if (bitstream_get (state, 1))	/* timecod1e */
	bitstream_get (state, 14);	/* timecod1 */
    if (bitstream_get (state, 1))	/* timecod2e */
	bitstream_get (state, 14);	/* timecod2 */

    if (bitstream_get (state, 1)) {	/* addbsie */
	int addbsil;

	addbsil = bitstream_get (state, 6);
	do {
	    bitstream_get (state, 8);	/* addbsi */
	} while (addbsil--);
    }

    return 0;
}

void a52_dynrng (a52_state_t * state,
		 level_t (* call) (level_t, void *), void * data)
{
    state->dynrnge = 0;
    if (call) {
	state->dynrnge = 1;
	state->dynrngcall = call;
	state->dynrngdata = data;
    }
}

static int parse_exponents (a52_state_t * state, int expstr, int ngrps,
			    uint8_t exponent, uint8_t * dest)
{
    int exps;

    while (ngrps--) {
	exps = bitstream_get (state, 7);

	exponent += exp_1[exps];
	if (exponent > 24)
	    return 1;

	switch (expstr) {
	case EXP_D45:
	    *(dest++) = exponent;
	    *(dest++) = exponent;
	case EXP_D25:
	    *(dest++) = exponent;
	case EXP_D15:
	    *(dest++) = exponent;
	}

	exponent += exp_2[exps];
	if (exponent > 24)
	    return 1;

	switch (expstr) {
	case EXP_D45:
	    *(dest++) = exponent;
	    *(dest++) = exponent;
	case EXP_D25:
	    *(dest++) = exponent;
	case EXP_D15:
	    *(dest++) = exponent;
	}

	exponent += exp_3[exps];
	if (exponent > 24)
	    return 1;

	switch (expstr) {
	case EXP_D45:
	    *(dest++) = exponent;
	    *(dest++) = exponent;
	case EXP_D25:
	    *(dest++) = exponent;
	case EXP_D15:
	    *(dest++) = exponent;
	}
    }	

    return 0;
}

static int parse_deltba (a52_state_t * state, int8_t * deltba)
{
    int deltnseg, deltlen, delta, j;

    memset (deltba, 0, 50);

    deltnseg = bitstream_get (state, 3);
    j = 0;
    do {
	j += bitstream_get (state, 5);
	deltlen = bitstream_get (state, 4);
	delta = bitstream_get (state, 3);
	delta -= (delta >= 4) ? 3 : 4;
	if (!deltlen)
	    continue;
	if (j + deltlen >= 50)
	    return 1;
	while (deltlen--)
	    deltba[j++] = delta;
    } while (deltnseg--);

    return 0;
}

static inline int zero_snr_offsets (int nfchans, a52_state_t * state)
{
    int i;

    if ((state->csnroffst) ||
	(state->chincpl && state->cplba.bai >> 3) ||	/* cplinu, fsnroffst */
	(state->lfeon && state->lfeba.bai >> 3))	/* fsnroffst */
	return 0;
    for (i = 0; i < nfchans; i++)
	if (state->ba[i].bai >> 3)			/* fsnroffst */
	    return 0;
    return 1;
}

static inline int16_t dither_gen (a52_state_t * state)
{
    int16_t nstate;

    nstate = dither_lut[state->lfsr_state >> 8] ^ (state->lfsr_state << 8);
	
    state->lfsr_state = (uint16_t) nstate;

    return (3 * nstate) >> 2;
}

#ifndef LIBA52_FIXED
#define COEFF(c,t,l,s,e) (c) = (t) * (s)[e]
#else
#define COEFF(c,_t,_l,s,e) do {					\
    quantizer_t t = (_t);					\
    level_t l = (_l);						\
    int shift = e - 5;						\
    sample_t tmp = t * (l >> 16) + ((t * (l & 0xffff)) >> 16);	\
    if (shift >= 0)						\
	(c) = tmp >> shift;					\
    else							\
	(c) = tmp << -shift;					\
} while (0)
#endif

static void coeff_get (a52_state_t * state, sample_t * coeff,
		       expbap_t * expbap, quantizer_set_t * quant,
		       level_t level, int dither, int end)
{
    int i;
    uint8_t * exp;
    int8_t * bap;

#ifndef LIBA52_FIXED
    sample_t factor[25];

    for (i = 0; i <= 24; i++)
	factor[i] = scale_factor[i] * level;
#endif

    exp = expbap->exp;
    bap = expbap->bap;

    for (i = 0; i < end; i++) {
	int bapi;

	bapi = bap[i];
	switch (bapi) {
	case 0:
	    if (dither) {
		COEFF (coeff[i], dither_gen (state), level, factor, exp[i]);
		continue;
	    } else {
		coeff[i] = 0;
		continue;
	    }

	case -1:
	    if (quant->q1_ptr >= 0) {
		COEFF (coeff[i], quant->q1[quant->q1_ptr--], level,
		       factor, exp[i]);
		continue;
	    } else {
		int code;

		code = bitstream_get (state, 5);

		quant->q1_ptr = 1;
		quant->q1[0] = q_1_2[code];
		quant->q1[1] = q_1_1[code];
		COEFF (coeff[i], q_1_0[code], level, factor, exp[i]);
		continue;
	    }

	case -2:
	    if (quant->q2_ptr >= 0) {
		COEFF (coeff[i], quant->q2[quant->q2_ptr--], level,
		       factor, exp[i]);
		continue;
	    } else {
		int code;

		code = bitstream_get (state, 7);

		quant->q2_ptr = 1;
		quant->q2[0] = q_2_2[code];
		quant->q2[1] = q_2_1[code];
		COEFF (coeff[i], q_2_0[code], level, factor, exp[i]);
		continue;
	    }

	case 3:
	    COEFF (coeff[i], q_3[bitstream_get (state, 3)], level,
		   factor, exp[i]);
	    continue;

	case -3:
	    if (quant->q4_ptr == 0) {
		quant->q4_ptr = -1;
		COEFF (coeff[i], quant->q4, level, factor, exp[i]);
		continue;
	    } else {
		int code;

		code = bitstream_get (state, 7);

		quant->q4_ptr = 0;
		quant->q4 = q_4_1[code];
		COEFF (coeff[i], q_4_0[code], level, factor, exp[i]);
		continue;
	    }

	case 4:
	    COEFF (coeff[i], q_5[bitstream_get (state, 4)], level,
		   factor, exp[i]);
	    continue;

	default:
	    COEFF (coeff[i], bitstream_get_2 (state, bapi) << (16 - bapi),
		   level, factor, exp[i]);
	}
    }
}

static void coeff_get_coupling (a52_state_t * state, int nfchans,
				level_t * coeff, sample_t (* samples)[256],
				quantizer_set_t * quant, uint8_t dithflag[5])
{
    int cplbndstrc, bnd, i, i_end, ch;
    uint8_t * exp;
    int8_t * bap;
    level_t cplco[5];

    exp = state->cpl_expbap.exp;
    bap = state->cpl_expbap.bap;
    bnd = 0;
    cplbndstrc = state->cplbndstrc;
    i = state->cplstrtmant;
    while (i < state->cplendmant) {
	i_end = i + 12;
	while (cplbndstrc & 1) {
	    cplbndstrc >>= 1;
	    i_end += 12;
	}
	cplbndstrc >>= 1;
	for (ch = 0; ch < nfchans; ch++)
	    cplco[ch] = MUL_L (state->cplco[ch][bnd], coeff[ch]);
	bnd++;

	while (i < i_end) {
	    quantizer_t cplcoeff;
	    int bapi;

	    bapi = bap[i];
	    switch (bapi) {
	    case 0:
		for (ch = 0; ch < nfchans; ch++)
		    if ((state->chincpl >> ch) & 1) {
			if (dithflag[ch])
#ifndef LIBA52_FIXED
			    samples[ch][i] = (scale_factor[exp[i]] *
					      cplco[ch] * dither_gen (state));
#else
			    COEFF (samples[ch][i], dither_gen (state),
				   cplco[ch], scale_factor, exp[i]);
#endif
			else