cannam@85: /* cannam@85: * libmad - MPEG audio decoder library cannam@85: * Copyright (C) 2000-2004 Underbit Technologies, Inc. cannam@85: * cannam@85: * This program is free software; you can redistribute it and/or modify cannam@85: * it under the terms of the GNU General Public License as published by cannam@85: * the Free Software Foundation; either version 2 of the License, or cannam@85: * (at your option) any later version. cannam@85: * cannam@85: * This program is distributed in the hope that it will be useful, cannam@85: * but WITHOUT ANY WARRANTY; without even the implied warranty of cannam@85: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the cannam@85: * GNU General Public License for more details. cannam@85: * cannam@85: * You should have received a copy of the GNU General Public License cannam@85: * along with this program; if not, write to the Free Software cannam@85: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA cannam@85: * cannam@85: * $Id: layer12.c,v 1.17 2004/02/05 09:02:39 rob Exp $ cannam@85: */ cannam@85: cannam@85: # ifdef HAVE_CONFIG_H cannam@85: # include "config.h" cannam@85: # endif cannam@85: cannam@85: # include "global.h" cannam@85: cannam@85: # ifdef HAVE_LIMITS_H cannam@85: # include cannam@85: # else cannam@85: # define CHAR_BIT 8 cannam@85: # endif cannam@85: cannam@85: # include "fixed.h" cannam@85: # include "bit.h" cannam@85: # include "stream.h" cannam@85: # include "frame.h" cannam@85: # include "layer12.h" cannam@85: cannam@85: /* cannam@85: * scalefactor table cannam@85: * used in both Layer I and Layer II decoding cannam@85: */ cannam@85: static cannam@85: mad_fixed_t const sf_table[64] = { cannam@85: # include "sf_table.dat" cannam@85: }; cannam@85: cannam@85: /* --- Layer I ------------------------------------------------------------- */ cannam@85: cannam@85: /* linear scaling table */ cannam@85: static cannam@85: mad_fixed_t const linear_table[14] = { cannam@85: MAD_F(0x15555555), /* 2^2 / (2^2 - 1) == 1.33333333333333 */ cannam@85: MAD_F(0x12492492), /* 2^3 / (2^3 - 1) == 1.14285714285714 */ cannam@85: MAD_F(0x11111111), /* 2^4 / (2^4 - 1) == 1.06666666666667 */ cannam@85: MAD_F(0x10842108), /* 2^5 / (2^5 - 1) == 1.03225806451613 */ cannam@85: MAD_F(0x10410410), /* 2^6 / (2^6 - 1) == 1.01587301587302 */ cannam@85: MAD_F(0x10204081), /* 2^7 / (2^7 - 1) == 1.00787401574803 */ cannam@85: MAD_F(0x10101010), /* 2^8 / (2^8 - 1) == 1.00392156862745 */ cannam@85: MAD_F(0x10080402), /* 2^9 / (2^9 - 1) == 1.00195694716243 */ cannam@85: MAD_F(0x10040100), /* 2^10 / (2^10 - 1) == 1.00097751710655 */ cannam@85: MAD_F(0x10020040), /* 2^11 / (2^11 - 1) == 1.00048851978505 */ cannam@85: MAD_F(0x10010010), /* 2^12 / (2^12 - 1) == 1.00024420024420 */ cannam@85: MAD_F(0x10008004), /* 2^13 / (2^13 - 1) == 1.00012208521548 */ cannam@85: MAD_F(0x10004001), /* 2^14 / (2^14 - 1) == 1.00006103888177 */ cannam@85: MAD_F(0x10002000) /* 2^15 / (2^15 - 1) == 1.00003051850948 */ cannam@85: }; cannam@85: cannam@85: /* cannam@85: * NAME: I_sample() cannam@85: * DESCRIPTION: decode one requantized Layer I sample from a bitstream cannam@85: */ cannam@85: static cannam@85: mad_fixed_t I_sample(struct mad_bitptr *ptr, unsigned int nb) cannam@85: { cannam@85: mad_fixed_t sample; cannam@85: cannam@85: sample = mad_bit_read(ptr, nb); cannam@85: cannam@85: /* invert most significant bit, extend sign, then scale to fixed format */ cannam@85: cannam@85: sample ^= 1 << (nb - 1); cannam@85: sample |= -(sample & (1 << (nb - 1))); cannam@85: cannam@85: sample <<= MAD_F_FRACBITS - (nb - 1); cannam@85: cannam@85: /* requantize the sample */ cannam@85: cannam@85: /* s'' = (2^nb / (2^nb - 1)) * (s''' + 2^(-nb + 1)) */ cannam@85: cannam@85: sample += MAD_F_ONE >> (nb - 1); cannam@85: cannam@85: return mad_f_mul(sample, linear_table[nb - 2]); cannam@85: cannam@85: /* s' = factor * s'' */ cannam@85: /* (to be performed by caller) */ cannam@85: } cannam@85: cannam@85: /* cannam@85: * NAME: layer->I() cannam@85: * DESCRIPTION: decode a single Layer I frame cannam@85: */ cannam@85: int mad_layer_I(struct mad_stream *stream, struct mad_frame *frame) cannam@85: { cannam@85: struct mad_header *header = &frame->header; cannam@85: unsigned int nch, bound, ch, s, sb, nb; cannam@85: unsigned char allocation[2][32], scalefactor[2][32]; cannam@85: cannam@85: nch = MAD_NCHANNELS(header); cannam@85: cannam@85: bound = 32; cannam@85: if (header->mode == MAD_MODE_JOINT_STEREO) { cannam@85: header->flags |= MAD_FLAG_I_STEREO; cannam@85: bound = 4 + header->mode_extension * 4; cannam@85: } cannam@85: cannam@85: /* check CRC word */ cannam@85: cannam@85: if (header->flags & MAD_FLAG_PROTECTION) { cannam@85: header->crc_check = cannam@85: mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)), cannam@85: header->crc_check); cannam@85: cannam@85: if (header->crc_check != header->crc_target && cannam@85: !(frame->options & MAD_OPTION_IGNORECRC)) { cannam@85: stream->error = MAD_ERROR_BADCRC; cannam@85: return -1; cannam@85: } cannam@85: } cannam@85: cannam@85: /* decode bit allocations */ cannam@85: cannam@85: for (sb = 0; sb < bound; ++sb) { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: nb = mad_bit_read(&stream->ptr, 4); cannam@85: cannam@85: if (nb == 15) { cannam@85: stream->error = MAD_ERROR_BADBITALLOC; cannam@85: return -1; cannam@85: } cannam@85: cannam@85: allocation[ch][sb] = nb ? nb + 1 : 0; cannam@85: } cannam@85: } cannam@85: cannam@85: for (sb = bound; sb < 32; ++sb) { cannam@85: nb = mad_bit_read(&stream->ptr, 4); cannam@85: cannam@85: if (nb == 15) { cannam@85: stream->error = MAD_ERROR_BADBITALLOC; cannam@85: return -1; cannam@85: } cannam@85: cannam@85: allocation[0][sb] = cannam@85: allocation[1][sb] = nb ? nb + 1 : 0; cannam@85: } cannam@85: cannam@85: /* decode scalefactors */ cannam@85: cannam@85: for (sb = 0; sb < 32; ++sb) { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: if (allocation[ch][sb]) { cannam@85: scalefactor[ch][sb] = mad_bit_read(&stream->ptr, 6); cannam@85: cannam@85: # if defined(OPT_STRICT) cannam@85: /* cannam@85: * Scalefactor index 63 does not appear in Table B.1 of cannam@85: * ISO/IEC 11172-3. Nonetheless, other implementations accept it, cannam@85: * so we only reject it if OPT_STRICT is defined. cannam@85: */ cannam@85: if (scalefactor[ch][sb] == 63) { cannam@85: stream->error = MAD_ERROR_BADSCALEFACTOR; cannam@85: return -1; cannam@85: } cannam@85: # endif cannam@85: } cannam@85: } cannam@85: } cannam@85: cannam@85: /* decode samples */ cannam@85: cannam@85: for (s = 0; s < 12; ++s) { cannam@85: for (sb = 0; sb < bound; ++sb) { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: nb = allocation[ch][sb]; cannam@85: frame->sbsample[ch][s][sb] = nb ? cannam@85: mad_f_mul(I_sample(&stream->ptr, nb), cannam@85: sf_table[scalefactor[ch][sb]]) : 0; cannam@85: } cannam@85: } cannam@85: cannam@85: for (sb = bound; sb < 32; ++sb) { cannam@85: if ((nb = allocation[0][sb])) { cannam@85: mad_fixed_t sample; cannam@85: cannam@85: sample = I_sample(&stream->ptr, nb); cannam@85: cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: frame->sbsample[ch][s][sb] = cannam@85: mad_f_mul(sample, sf_table[scalefactor[ch][sb]]); cannam@85: } cannam@85: } cannam@85: else { cannam@85: for (ch = 0; ch < nch; ++ch) cannam@85: frame->sbsample[ch][s][sb] = 0; cannam@85: } cannam@85: } cannam@85: } cannam@85: cannam@85: return 0; cannam@85: } cannam@85: cannam@85: /* --- Layer II ------------------------------------------------------------ */ cannam@85: cannam@85: /* possible quantization per subband table */ cannam@85: static cannam@85: struct { cannam@85: unsigned int sblimit; cannam@85: unsigned char const offsets[30]; cannam@85: } const sbquant_table[5] = { cannam@85: /* ISO/IEC 11172-3 Table B.2a */ cannam@85: { 27, { 7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, /* 0 */ cannam@85: 3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0 } }, cannam@85: /* ISO/IEC 11172-3 Table B.2b */ cannam@85: { 30, { 7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, /* 1 */ cannam@85: 3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0, 0, 0, 0 } }, cannam@85: /* ISO/IEC 11172-3 Table B.2c */ cannam@85: { 8, { 5, 5, 2, 2, 2, 2, 2, 2 } }, /* 2 */ cannam@85: /* ISO/IEC 11172-3 Table B.2d */ cannam@85: { 12, { 5, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 } }, /* 3 */ cannam@85: /* ISO/IEC 13818-3 Table B.1 */ cannam@85: { 30, { 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, /* 4 */ cannam@85: 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } } cannam@85: }; cannam@85: cannam@85: /* bit allocation table */ cannam@85: static cannam@85: struct { cannam@85: unsigned short nbal; cannam@85: unsigned short offset; cannam@85: } const bitalloc_table[8] = { cannam@85: { 2, 0 }, /* 0 */ cannam@85: { 2, 3 }, /* 1 */ cannam@85: { 3, 3 }, /* 2 */ cannam@85: { 3, 1 }, /* 3 */ cannam@85: { 4, 2 }, /* 4 */ cannam@85: { 4, 3 }, /* 5 */ cannam@85: { 4, 4 }, /* 6 */ cannam@85: { 4, 5 } /* 7 */ cannam@85: }; cannam@85: cannam@85: /* offsets into quantization class table */ cannam@85: static cannam@85: unsigned char const offset_table[6][15] = { cannam@85: { 0, 1, 16 }, /* 0 */ cannam@85: { 0, 1, 2, 3, 4, 5, 16 }, /* 1 */ cannam@85: { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 }, /* 2 */ cannam@85: { 0, 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }, /* 3 */ cannam@85: { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16 }, /* 4 */ cannam@85: { 0, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 } /* 5 */ cannam@85: }; cannam@85: cannam@85: /* quantization class table */ cannam@85: static cannam@85: struct quantclass { cannam@85: unsigned short nlevels; cannam@85: unsigned char group; cannam@85: unsigned char bits; cannam@85: mad_fixed_t C; cannam@85: mad_fixed_t D; cannam@85: } const qc_table[17] = { cannam@85: # include "qc_table.dat" cannam@85: }; cannam@85: cannam@85: /* cannam@85: * NAME: II_samples() cannam@85: * DESCRIPTION: decode three requantized Layer II samples from a bitstream cannam@85: */ cannam@85: static cannam@85: void II_samples(struct mad_bitptr *ptr, cannam@85: struct quantclass const *quantclass, cannam@85: mad_fixed_t output[3]) cannam@85: { cannam@85: unsigned int nb, s, sample[3]; cannam@85: cannam@85: if ((nb = quantclass->group)) { cannam@85: unsigned int c, nlevels; cannam@85: cannam@85: /* degrouping */ cannam@85: c = mad_bit_read(ptr, quantclass->bits); cannam@85: nlevels = quantclass->nlevels; cannam@85: cannam@85: for (s = 0; s < 3; ++s) { cannam@85: sample[s] = c % nlevels; cannam@85: c /= nlevels; cannam@85: } cannam@85: } cannam@85: else { cannam@85: nb = quantclass->bits; cannam@85: cannam@85: for (s = 0; s < 3; ++s) cannam@85: sample[s] = mad_bit_read(ptr, nb); cannam@85: } cannam@85: cannam@85: for (s = 0; s < 3; ++s) { cannam@85: mad_fixed_t requantized; cannam@85: cannam@85: /* invert most significant bit, extend sign, then scale to fixed format */ cannam@85: cannam@85: requantized = sample[s] ^ (1 << (nb - 1)); cannam@85: requantized |= -(requantized & (1 << (nb - 1))); cannam@85: cannam@85: requantized <<= MAD_F_FRACBITS - (nb - 1); cannam@85: cannam@85: /* requantize the sample */ cannam@85: cannam@85: /* s'' = C * (s''' + D) */ cannam@85: cannam@85: output[s] = mad_f_mul(requantized + quantclass->D, quantclass->C); cannam@85: cannam@85: /* s' = factor * s'' */ cannam@85: /* (to be performed by caller) */ cannam@85: } cannam@85: } cannam@85: cannam@85: /* cannam@85: * NAME: layer->II() cannam@85: * DESCRIPTION: decode a single Layer II frame cannam@85: */ cannam@85: int mad_layer_II(struct mad_stream *stream, struct mad_frame *frame) cannam@85: { cannam@85: struct mad_header *header = &frame->header; cannam@85: struct mad_bitptr start; cannam@85: unsigned int index, sblimit, nbal, nch, bound, gr, ch, s, sb; cannam@85: unsigned char const *offsets; cannam@85: unsigned char allocation[2][32], scfsi[2][32], scalefactor[2][32][3]; cannam@85: mad_fixed_t samples[3]; cannam@85: cannam@85: nch = MAD_NCHANNELS(header); cannam@85: cannam@85: if (header->flags & MAD_FLAG_LSF_EXT) cannam@85: index = 4; cannam@85: else if (header->flags & MAD_FLAG_FREEFORMAT) cannam@85: goto freeformat; cannam@85: else { cannam@85: unsigned long bitrate_per_channel; cannam@85: cannam@85: bitrate_per_channel = header->bitrate; cannam@85: if (nch == 2) { cannam@85: bitrate_per_channel /= 2; cannam@85: cannam@85: # if defined(OPT_STRICT) cannam@85: /* cannam@85: * ISO/IEC 11172-3 allows only single channel mode for 32, 48, 56, and cannam@85: * 80 kbps bitrates in Layer II, but some encoders ignore this cannam@85: * restriction. We enforce it if OPT_STRICT is defined. cannam@85: */ cannam@85: if (bitrate_per_channel <= 28000 || bitrate_per_channel == 40000) { cannam@85: stream->error = MAD_ERROR_BADMODE; cannam@85: return -1; cannam@85: } cannam@85: # endif cannam@85: } cannam@85: else { /* nch == 1 */ cannam@85: if (bitrate_per_channel > 192000) { cannam@85: /* cannam@85: * ISO/IEC 11172-3 does not allow single channel mode for 224, 256, cannam@85: * 320, or 384 kbps bitrates in Layer II. cannam@85: */ cannam@85: stream->error = MAD_ERROR_BADMODE; cannam@85: return -1; cannam@85: } cannam@85: } cannam@85: cannam@85: if (bitrate_per_channel <= 48000) cannam@85: index = (header->samplerate == 32000) ? 3 : 2; cannam@85: else if (bitrate_per_channel <= 80000) cannam@85: index = 0; cannam@85: else { cannam@85: freeformat: cannam@85: index = (header->samplerate == 48000) ? 0 : 1; cannam@85: } cannam@85: } cannam@85: cannam@85: sblimit = sbquant_table[index].sblimit; cannam@85: offsets = sbquant_table[index].offsets; cannam@85: cannam@85: bound = 32; cannam@85: if (header->mode == MAD_MODE_JOINT_STEREO) { cannam@85: header->flags |= MAD_FLAG_I_STEREO; cannam@85: bound = 4 + header->mode_extension * 4; cannam@85: } cannam@85: cannam@85: if (bound > sblimit) cannam@85: bound = sblimit; cannam@85: cannam@85: start = stream->ptr; cannam@85: cannam@85: /* decode bit allocations */ cannam@85: cannam@85: for (sb = 0; sb < bound; ++sb) { cannam@85: nbal = bitalloc_table[offsets[sb]].nbal; cannam@85: cannam@85: for (ch = 0; ch < nch; ++ch) cannam@85: allocation[ch][sb] = mad_bit_read(&stream->ptr, nbal); cannam@85: } cannam@85: cannam@85: for (sb = bound; sb < sblimit; ++sb) { cannam@85: nbal = bitalloc_table[offsets[sb]].nbal; cannam@85: cannam@85: allocation[0][sb] = cannam@85: allocation[1][sb] = mad_bit_read(&stream->ptr, nbal); cannam@85: } cannam@85: cannam@85: /* decode scalefactor selection info */ cannam@85: cannam@85: for (sb = 0; sb < sblimit; ++sb) { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: if (allocation[ch][sb]) cannam@85: scfsi[ch][sb] = mad_bit_read(&stream->ptr, 2); cannam@85: } cannam@85: } cannam@85: cannam@85: /* check CRC word */ cannam@85: cannam@85: if (header->flags & MAD_FLAG_PROTECTION) { cannam@85: header->crc_check = cannam@85: mad_bit_crc(start, mad_bit_length(&start, &stream->ptr), cannam@85: header->crc_check); cannam@85: cannam@85: if (header->crc_check != header->crc_target && cannam@85: !(frame->options & MAD_OPTION_IGNORECRC)) { cannam@85: stream->error = MAD_ERROR_BADCRC; cannam@85: return -1; cannam@85: } cannam@85: } cannam@85: cannam@85: /* decode scalefactors */ cannam@85: cannam@85: for (sb = 0; sb < sblimit; ++sb) { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: if (allocation[ch][sb]) { cannam@85: scalefactor[ch][sb][0] = mad_bit_read(&stream->ptr, 6); cannam@85: cannam@85: switch (scfsi[ch][sb]) { cannam@85: case 2: cannam@85: scalefactor[ch][sb][2] = cannam@85: scalefactor[ch][sb][1] = cannam@85: scalefactor[ch][sb][0]; cannam@85: break; cannam@85: cannam@85: case 0: cannam@85: scalefactor[ch][sb][1] = mad_bit_read(&stream->ptr, 6); cannam@85: /* fall through */ cannam@85: cannam@85: case 1: cannam@85: case 3: cannam@85: scalefactor[ch][sb][2] = mad_bit_read(&stream->ptr, 6); cannam@85: } cannam@85: cannam@85: if (scfsi[ch][sb] & 1) cannam@85: scalefactor[ch][sb][1] = scalefactor[ch][sb][scfsi[ch][sb] - 1]; cannam@85: cannam@85: # if defined(OPT_STRICT) cannam@85: /* cannam@85: * Scalefactor index 63 does not appear in Table B.1 of cannam@85: * ISO/IEC 11172-3. Nonetheless, other implementations accept it, cannam@85: * so we only reject it if OPT_STRICT is defined. cannam@85: */ cannam@85: if (scalefactor[ch][sb][0] == 63 || cannam@85: scalefactor[ch][sb][1] == 63 || cannam@85: scalefactor[ch][sb][2] == 63) { cannam@85: stream->error = MAD_ERROR_BADSCALEFACTOR; cannam@85: return -1; cannam@85: } cannam@85: # endif cannam@85: } cannam@85: } cannam@85: } cannam@85: cannam@85: /* decode samples */ cannam@85: cannam@85: for (gr = 0; gr < 12; ++gr) { cannam@85: for (sb = 0; sb < bound; ++sb) { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: if ((index = allocation[ch][sb])) { cannam@85: index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1]; cannam@85: cannam@85: II_samples(&stream->ptr, &qc_table[index], samples); cannam@85: cannam@85: for (s = 0; s < 3; ++s) { cannam@85: frame->sbsample[ch][3 * gr + s][sb] = cannam@85: mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]); cannam@85: } cannam@85: } cannam@85: else { cannam@85: for (s = 0; s < 3; ++s) cannam@85: frame->sbsample[ch][3 * gr + s][sb] = 0; cannam@85: } cannam@85: } cannam@85: } cannam@85: cannam@85: for (sb = bound; sb < sblimit; ++sb) { cannam@85: if ((index = allocation[0][sb])) { cannam@85: index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1]; cannam@85: cannam@85: II_samples(&stream->ptr, &qc_table[index], samples); cannam@85: cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: for (s = 0; s < 3; ++s) { cannam@85: frame->sbsample[ch][3 * gr + s][sb] = cannam@85: mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]); cannam@85: } cannam@85: } cannam@85: } cannam@85: else { cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: for (s = 0; s < 3; ++s) cannam@85: frame->sbsample[ch][3 * gr + s][sb] = 0; cannam@85: } cannam@85: } cannam@85: } cannam@85: cannam@85: for (ch = 0; ch < nch; ++ch) { cannam@85: for (s = 0; s < 3; ++s) { cannam@85: for (sb = sblimit; sb < 32; ++sb) cannam@85: frame->sbsample[ch][3 * gr + s][sb] = 0; cannam@85: } cannam@85: } cannam@85: } cannam@85: cannam@85: return 0; cannam@85: }