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-rw-r--r--src/libmad/layer12.c510
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diff --git a/src/libmad/layer12.c b/src/libmad/layer12.c
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+/*
+ * libmad - MPEG audio decoder library
+ * Copyright (C) 2000-2003 Underbit Technologies, Inc.
+ *
+ * This program 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.
+ *
+ * This program 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
+ *
+ * $Id: layer12.c,v 1.1 2003/08/14 03:57:13 shank Exp $
+ */
+
+# ifdef HAVE_CONFIG_H
+# include "config.h"
+# endif
+
+# include "global.h"
+
+# ifdef HAVE_LIMITS_H
+# include <limits.h>
+# else
+# define CHAR_BIT 8
+# endif
+
+# include "fixed.h"
+# include "bit.h"
+# include "stream.h"
+# include "frame.h"
+# include "layer12.h"
+
+/*
+ * scalefactor table
+ * used in both Layer I and Layer II decoding
+ */
+static
+mad_fixed_t const sf_table[64] = {
+# include "sf_table.dat"
+};
+
+/* --- Layer I ------------------------------------------------------------- */
+
+/* linear scaling table */
+static
+mad_fixed_t const linear_table[14] = {
+ MAD_F(0x15555555), /* 2^2 / (2^2 - 1) == 1.33333333333333 */
+ MAD_F(0x12492492), /* 2^3 / (2^3 - 1) == 1.14285714285714 */
+ MAD_F(0x11111111), /* 2^4 / (2^4 - 1) == 1.06666666666667 */
+ MAD_F(0x10842108), /* 2^5 / (2^5 - 1) == 1.03225806451613 */
+ MAD_F(0x10410410), /* 2^6 / (2^6 - 1) == 1.01587301587302 */
+ MAD_F(0x10204081), /* 2^7 / (2^7 - 1) == 1.00787401574803 */
+ MAD_F(0x10101010), /* 2^8 / (2^8 - 1) == 1.00392156862745 */
+ MAD_F(0x10080402), /* 2^9 / (2^9 - 1) == 1.00195694716243 */
+ MAD_F(0x10040100), /* 2^10 / (2^10 - 1) == 1.00097751710655 */
+ MAD_F(0x10020040), /* 2^11 / (2^11 - 1) == 1.00048851978505 */
+ MAD_F(0x10010010), /* 2^12 / (2^12 - 1) == 1.00024420024420 */
+ MAD_F(0x10008004), /* 2^13 / (2^13 - 1) == 1.00012208521548 */
+ MAD_F(0x10004001), /* 2^14 / (2^14 - 1) == 1.00006103888177 */
+ MAD_F(0x10002000) /* 2^15 / (2^15 - 1) == 1.00003051850948 */
+};
+
+/*
+ * NAME: I_sample()
+ * DESCRIPTION: decode one requantized Layer I sample from a bitstream
+ */
+static
+mad_fixed_t I_sample(struct mad_bitptr *ptr, unsigned int nb)
+{
+ mad_fixed_t sample;
+
+ sample = mad_bit_read(ptr, nb);
+
+ /* invert most significant bit, extend sign, then scale to fixed format */
+
+ sample ^= 1 << (nb - 1);
+ sample |= -(sample & (1 << (nb - 1)));
+
+ sample <<= MAD_F_FRACBITS - (nb - 1);
+
+ /* requantize the sample */
+
+ /* s'' = (2^nb / (2^nb - 1)) * (s''' + 2^(-nb + 1)) */
+
+ sample += MAD_F_ONE >> (nb - 1);
+
+ return mad_f_mul(sample, linear_table[nb - 2]);
+
+ /* s' = factor * s'' */
+ /* (to be performed by caller) */
+}
+
+/*
+ * NAME: layer->I()
+ * DESCRIPTION: decode a single Layer I frame
+ */
+int mad_layer_I(struct mad_stream *stream, struct mad_frame *frame)
+{
+ struct mad_header *header = &frame->header;
+ unsigned int nch, bound, ch, s, sb, nb;
+ unsigned char allocation[2][32], scalefactor[2][32];
+
+ nch = MAD_NCHANNELS(header);
+
+ bound = 32;
+ if (header->mode == MAD_MODE_JOINT_STEREO) {
+ header->flags |= MAD_FLAG_I_STEREO;
+ bound = 4 + header->mode_extension * 4;
+ }
+
+ /* check CRC word */
+
+ if (header->flags & MAD_FLAG_PROTECTION) {
+ header->crc_check =
+ mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)),
+ header->crc_check);
+
+ if (header->crc_check != header->crc_target &&
+ !(frame->options & MAD_OPTION_IGNORECRC)) {
+ stream->error = MAD_ERROR_BADCRC;
+ return -1;
+ }
+ }
+
+ /* decode bit allocations */
+
+ for (sb = 0; sb < bound; ++sb) {
+ for (ch = 0; ch < nch; ++ch) {
+ nb = mad_bit_read(&stream->ptr, 4);
+
+ if (nb == 15) {
+ stream->error = MAD_ERROR_BADBITALLOC;
+ return -1;
+ }
+
+ allocation[ch][sb] = nb ? nb + 1 : 0;
+ }
+ }
+
+ for (sb = bound; sb < 32; ++sb) {
+ nb = mad_bit_read(&stream->ptr, 4);
+
+ if (nb == 15) {
+ stream->error = MAD_ERROR_BADBITALLOC;
+ return -1;
+ }
+
+ allocation[0][sb] =
+ allocation[1][sb] = nb ? nb + 1 : 0;
+ }
+
+ /* decode scalefactors */
+
+ for (sb = 0; sb < 32; ++sb) {
+ for (ch = 0; ch < nch; ++ch) {
+ if (allocation[ch][sb]) {
+ scalefactor[ch][sb] = mad_bit_read(&stream->ptr, 6);
+
+# if defined(OPT_STRICT)
+ /*
+ * Scalefactor index 63 does not appear in Table B.1 of
+ * ISO/IEC 11172-3. Nonetheless, other implementations accept it,
+ * so we only reject it if OPT_STRICT is defined.
+ */
+ if (scalefactor[ch][sb] == 63) {
+ stream->error = MAD_ERROR_BADSCALEFACTOR;
+ return -1;
+ }
+# endif
+ }
+ }
+ }
+
+ /* decode samples */
+
+ for (s = 0; s < 12; ++s) {
+ for (sb = 0; sb < bound; ++sb) {
+ for (ch = 0; ch < nch; ++ch) {
+ nb = allocation[ch][sb];
+ frame->sbsample[ch][s][sb] = nb ?
+ mad_f_mul(I_sample(&stream->ptr, nb),
+ sf_table[scalefactor[ch][sb]]) : 0;
+ }
+ }
+
+ for (sb = bound; sb < 32; ++sb) {
+ if ((nb = allocation[0][sb])) {
+ mad_fixed_t sample;
+
+ sample = I_sample(&stream->ptr, nb);
+
+ for (ch = 0; ch < nch; ++ch) {
+ frame->sbsample[ch][s][sb] =
+ mad_f_mul(sample, sf_table[scalefactor[ch][sb]]);
+ }
+ }
+ else {
+ for (ch = 0; ch < nch; ++ch)
+ frame->sbsample[ch][s][sb] = 0;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/* --- Layer II ------------------------------------------------------------ */
+
+/* possible quantization per subband table */
+static
+struct {
+ unsigned int sblimit;
+ unsigned char const offsets[30];
+} const sbquant_table[5] = {
+ /* ISO/IEC 11172-3 Table B.2a */
+ { 27, { 7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, /* 0 */
+ 3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0 } },
+ /* ISO/IEC 11172-3 Table B.2b */
+ { 30, { 7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, /* 1 */
+ 3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0, 0, 0, 0 } },
+ /* ISO/IEC 11172-3 Table B.2c */
+ { 8, { 5, 5, 2, 2, 2, 2, 2, 2 } }, /* 2 */
+ /* ISO/IEC 11172-3 Table B.2d */
+ { 12, { 5, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 } }, /* 3 */
+ /* ISO/IEC 13818-3 Table B.1 */
+ { 30, { 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, /* 4 */
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } }
+};
+
+/* bit allocation table */
+static
+struct {
+ unsigned short nbal;
+ unsigned short offset;
+} const bitalloc_table[8] = {
+ { 2, 0 }, /* 0 */
+ { 2, 3 }, /* 1 */
+ { 3, 3 }, /* 2 */
+ { 3, 1 }, /* 3 */
+ { 4, 2 }, /* 4 */
+ { 4, 3 }, /* 5 */
+ { 4, 4 }, /* 6 */
+ { 4, 5 } /* 7 */
+};
+
+/* offsets into quantization class table */
+static
+unsigned char const offset_table[6][15] = {
+ { 0, 1, 16 }, /* 0 */
+ { 0, 1, 2, 3, 4, 5, 16 }, /* 1 */
+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 }, /* 2 */
+ { 0, 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }, /* 3 */
+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16 }, /* 4 */
+ { 0, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 } /* 5 */
+};
+
+/* quantization class table */
+static
+struct quantclass {
+ unsigned short nlevels;
+ unsigned char group;
+ unsigned char bits;
+ mad_fixed_t C;
+ mad_fixed_t D;
+} const qc_table[17] = {
+# include "qc_table.dat"
+};
+
+/*
+ * NAME: II_samples()
+ * DESCRIPTION: decode three requantized Layer II samples from a bitstream
+ */
+static
+void II_samples(struct mad_bitptr *ptr,
+ struct quantclass const *quantclass,
+ mad_fixed_t output[3])
+{
+ unsigned int nb, s, sample[3];
+
+ if ((nb = quantclass->group)) {
+ unsigned int c, nlevels;
+
+ /* degrouping */
+ c = mad_bit_read(ptr, quantclass->bits);
+ nlevels = quantclass->nlevels;
+
+ for (s = 0; s < 3; ++s) {
+ sample[s] = c % nlevels;
+ c /= nlevels;
+ }
+ }
+ else {
+ nb = quantclass->bits;
+
+ for (s = 0; s < 3; ++s)
+ sample[s] = mad_bit_read(ptr, nb);
+ }
+
+ for (s = 0; s < 3; ++s) {
+ mad_fixed_t requantized;
+
+ /* invert most significant bit, extend sign, then scale to fixed format */
+
+ requantized = sample[s] ^ (1 << (nb - 1));
+ requantized |= -(requantized & (1 << (nb - 1)));
+
+ requantized <<= MAD_F_FRACBITS - (nb - 1);
+
+ /* requantize the sample */
+
+ /* s'' = C * (s''' + D) */
+
+ output[s] = mad_f_mul(requantized + quantclass->D, quantclass->C);
+
+ /* s' = factor * s'' */
+ /* (to be performed by caller) */
+ }
+}
+
+/*
+ * NAME: layer->II()
+ * DESCRIPTION: decode a single Layer II frame
+ */
+int mad_layer_II(struct mad_stream *stream, struct mad_frame *frame)
+{
+ struct mad_header *header = &frame->header;
+ struct mad_bitptr start;
+ unsigned int index, sblimit, nbal, nch, bound, gr, ch, s, sb;
+ unsigned char const *offsets;
+ unsigned char allocation[2][32], scfsi[2][32], scalefactor[2][32][3];
+ mad_fixed_t samples[3];
+
+ nch = MAD_NCHANNELS(header);
+
+ if (header->flags & MAD_FLAG_LSF_EXT)
+ index = 4;
+ else {
+ switch (nch == 2 ? header->bitrate / 2 : header->bitrate) {
+ case 32000:
+ case 48000:
+ index = (header->samplerate == 32000) ? 3 : 2;
+ break;
+
+ case 56000:
+ case 64000:
+ case 80000:
+ index = 0;
+ break;
+
+ default:
+ index = (header->samplerate == 48000) ? 0 : 1;
+ }
+ }
+
+ sblimit = sbquant_table[index].sblimit;
+ offsets = sbquant_table[index].offsets;
+
+ bound = 32;
+ if (header->mode == MAD_MODE_JOINT_STEREO) {
+ header->flags |= MAD_FLAG_I_STEREO;
+ bound = 4 + header->mode_extension * 4;
+ }
+
+ if (bound > sblimit)
+ bound = sblimit;
+
+ start = stream->ptr;
+
+ /* decode bit allocations */
+
+ for (sb = 0; sb < bound; ++sb) {
+ nbal = bitalloc_table[offsets[sb]].nbal;
+
+ for (ch = 0; ch < nch; ++ch)
+ allocation[ch][sb] = mad_bit_read(&stream->ptr, nbal);
+ }
+
+ for (sb = bound; sb < sblimit; ++sb) {
+ nbal = bitalloc_table[offsets[sb]].nbal;
+
+ allocation[0][sb] =
+ allocation[1][sb] = mad_bit_read(&stream->ptr, nbal);
+ }
+
+ /* decode scalefactor selection info */
+
+ for (sb = 0; sb < sblimit; ++sb) {
+ for (ch = 0; ch < nch; ++ch) {
+ if (allocation[ch][sb])
+ scfsi[ch][sb] = mad_bit_read(&stream->ptr, 2);
+ }
+ }
+
+ /* check CRC word */
+
+ if (header->flags & MAD_FLAG_PROTECTION) {
+ header->crc_check =
+ mad_bit_crc(start, mad_bit_length(&start, &stream->ptr),
+ header->crc_check);
+
+ if (header->crc_check != header->crc_target &&
+ !(frame->options & MAD_OPTION_IGNORECRC)) {
+ stream->error = MAD_ERROR_BADCRC;
+ return -1;
+ }
+ }
+
+ /* decode scalefactors */
+
+ for (sb = 0; sb < sblimit; ++sb) {
+ for (ch = 0; ch < nch; ++ch) {
+ if (allocation[ch][sb]) {
+ scalefactor[ch][sb][0] = mad_bit_read(&stream->ptr, 6);
+
+ switch (scfsi[ch][sb]) {
+ case 2:
+ scalefactor[ch][sb][2] =
+ scalefactor[ch][sb][1] =
+ scalefactor[ch][sb][0];
+ break;
+
+ case 0:
+ scalefactor[ch][sb][1] = mad_bit_read(&stream->ptr, 6);
+ /* fall through */
+
+ case 1:
+ case 3:
+ scalefactor[ch][sb][2] = mad_bit_read(&stream->ptr, 6);
+ }
+
+ if (scfsi[ch][sb] & 1)
+ scalefactor[ch][sb][1] = scalefactor[ch][sb][scfsi[ch][sb] - 1];
+
+# if defined(OPT_STRICT)
+ /*
+ * Scalefactor index 63 does not appear in Table B.1 of
+ * ISO/IEC 11172-3. Nonetheless, other implementations accept it,
+ * so we only reject it if OPT_STRICT is defined.
+ */
+ if (scalefactor[ch][sb][0] == 63 ||
+ scalefactor[ch][sb][1] == 63 ||
+ scalefactor[ch][sb][2] == 63) {
+ stream->error = MAD_ERROR_BADSCALEFACTOR;
+ return -1;
+ }
+# endif
+ }
+ }
+ }
+
+ /* decode samples */
+
+ for (gr = 0; gr < 12; ++gr) {
+ for (sb = 0; sb < bound; ++sb) {
+ for (ch = 0; ch < nch; ++ch) {
+ if ((index = allocation[ch][sb])) {
+ index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1];
+
+ II_samples(&stream->ptr, &qc_table[index], samples);
+
+ for (s = 0; s < 3; ++s) {
+ frame->sbsample[ch][3 * gr + s][sb] =
+ mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]);
+ }
+ }
+ else {
+ for (s = 0; s < 3; ++s)
+ frame->sbsample[ch][3 * gr + s][sb] = 0;
+ }
+ }
+ }
+
+ for (sb = bound; sb < sblimit; ++sb) {
+ if ((index = allocation[0][sb])) {
+ index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1];
+
+ II_samples(&stream->ptr, &qc_table[index], samples);
+
+ for (ch = 0; ch < nch; ++ch) {
+ for (s = 0; s < 3; ++s) {
+ frame->sbsample[ch][3 * gr + s][sb] =
+ mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]);
+ }
+ }
+ }
+ else {
+ for (ch = 0; ch < nch; ++ch) {
+ for (s = 0; s < 3; ++s)
+ frame->sbsample[ch][3 * gr + s][sb] = 0;
+ }
+ }
+ }
+
+ for (ch = 0; ch < nch; ++ch) {
+ for (s = 0; s < 3; ++s) {
+ for (sb = sblimit; sb < 32; ++sb)
+ frame->sbsample[ch][3 * gr + s][sb] = 0;
+ }
+ }
+ }
+
+ return 0;
+}