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Diffstat (limited to 'src/libmad/layer12.c')
| -rw-r--r-- | src/libmad/layer12.c | 510 |
1 files changed, 510 insertions, 0 deletions
diff --git a/src/libmad/layer12.c b/src/libmad/layer12.c new file mode 100644 index 000000000..d14122a85 --- /dev/null +++ b/src/libmad/layer12.c @@ -0,0 +1,510 @@ +/* + * 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; +} |