mirror of
https://github.com/cookiengineer/audacity
synced 2025-04-30 15:49:41 +02:00
144 lines
4.2 KiB
C
144 lines
4.2 KiB
C
/*
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* TwoLAME: an optimized MPEG Audio Layer Two encoder
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*
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* Copyright (C) 2001-2004 Michael Cheng
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* Copyright (C) 2004-2006 The TwoLAME Project
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* $Id$
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*
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*/
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#include <stdio.h>
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#include <string.h>
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#include "twolame.h"
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#include "common.h"
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#include "dab.h"
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void
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dab_crc_calc(twolame_options * glopts,
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unsigned int bit_alloc[2][SBLIMIT],
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unsigned int scfsi[2][SBLIMIT],
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unsigned int scalar[2][3][SBLIMIT], unsigned int *crc, int packed)
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{
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int i, j, k;
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int nch = glopts->num_channels_out;
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int nb_scalar;
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int f[5] = { 0, 4, 8, 16, 30 };
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int first, last;
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first = f[packed];
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last = f[packed + 1];
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if (last > glopts->sblimit)
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last = glopts->sblimit;
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nb_scalar = 0;
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*crc = 0x0;
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for (i = first; i < last; i++)
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for (k = 0; k < nch; k++)
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if (bit_alloc[k][i]) /* above jsbound, bit_alloc[0][i] == ba[1][i] */
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switch (scfsi[k][i]) {
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case 0:
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for (j = 0; j < 3; j++) {
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nb_scalar++;
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dab_crc_update(scalar[k][j][i] >> 3, 3, crc);
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}
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break;
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case 1:
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case 3:
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nb_scalar += 2;
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dab_crc_update(scalar[k][0][i] >> 3, 3, crc);
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dab_crc_update(scalar[k][2][i] >> 3, 3, crc);
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break;
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case 2:
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nb_scalar++;
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dab_crc_update(scalar[k][0][i] >> 3, 3, crc);
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}
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}
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void dab_crc_update(unsigned int data, unsigned int length, unsigned int *crc)
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{
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unsigned int masking, carry;
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masking = 1 << length;
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while ((masking >>= 1)) {
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carry = *crc & 0x80;
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*crc <<= 1;
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if (!carry ^ !(data & masking))
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*crc ^= CRC8_POLYNOMIAL;
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}
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*crc &= 0xff;
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}
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#ifdef OLD_BROKEN_DAB_STUFF
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// Leaving these here while DAB is reimplemented properly
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#define MINIMUM 4 /* Minimum size of the buffer in bytes */
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#define MAX_LENGTH 32 /* Maximum length of word written */
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/*
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19 Jul 03
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DAB stuff got broken in the update to 02m
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Not sure who uses this. I would like to get it working again eventually.
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*/
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/*
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Just after the available bits calculation in twolame,
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allocated some bits for the DAB stuff
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*/
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if (header.dab_extension) {
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/* in 24 kHz we always have 4 bytes */
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if (header.sampling_frequency == 1)
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header.dab_extension = 4;
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/* You must have one frame in memory if you are in DAB mode */
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/* in conformity of the norme ETS 300 401 http://www.etsi.org */
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/* see bitstream.c */
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if (frameNum == 1)
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minimum = lg_frame + MINIMUM;
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adb -= header.dab_extension * 8 + header.dab_length * 8 + 16;
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}
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/*
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Just after we finishing padding up to the number of ADB
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Put the extension stuff in (ancillary data, right at the end)
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*/
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if (header.dab_extension) {
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/* Reserve some bytes for X-PAD in DAB mode */
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putbits(mybs, 0, header.dab_length * 8);
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for (i = header.dab_extension - 1; i >= 0; i--) {
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CRC_calcDAB(&frame, bit_alloc, scfsi, scalar, &crc, i);
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/* this crc is for the previous frame in DAB mode */
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if (mybs->buf_byte_idx + lg_frame < mybs->buf_size)
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mybs->buf[mybs->buf_byte_idx + lg_frame] = crc;
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/* reserved 2 bytes for F-PAD in DAB mode */
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putbits(mybs, crc, 8);
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}
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putbits(mybs, 0, 16);
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}
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#endif
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// vim:ts=4:sw=4:nowrap:
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