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/*
* ATRAC3+ compatible decoder
*
* Copyright (c) 2010-2013 Maxim Poliakovski
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* DSP functions for ATRAC3+ decoder.
*/
/**
* This file was borrowed from FFmpeg to test analysis PQF implementation
*/
#include <stdio.h>
#include <math.h>
#include <string.h>
#include "atrac3plusdsp.h"
#include "../atrac3plus_pqf_data.h"
/* lookup table for fast modulo 23 op required for cyclic buffers of the IPQF */
static const int mod23_lut[26] = {
23, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 0
};
// Just for test
static void dct4(float* out, const float* x, int N, float scale) {
for (int k = 0; k < N; k++) {
double sum = 0;
for (int n = 0; n < N; n++) {
sum += x[n] * cos((M_PI/N) * ((double)n + 0.5) * ((double)k + 0.5));
}
out[N - 1 - k] = sum * scale;
}
}
void ff_atrac3p_ipqf(Atrac3pIPQFChannelCtx *hist, const float *in, float *out)
{
int i, s, sb, t, pos_now, pos_next;
float idct_in[ATRAC3P_SUBBANDS];
float idct_out[ATRAC3P_SUBBANDS];
memset(out, 0, ATRAC3P_FRAME_SAMPLES * sizeof(*out));
for (s = 0; s < ATRAC3P_SUBBAND_SAMPLES; s++) {
/* pick up one sample from each subband */
for (sb = 0; sb < ATRAC3P_SUBBANDS; sb++)
idct_in[sb] = in[sb * ATRAC3P_SUBBAND_SAMPLES + s];
dct4(idct_out, idct_in, ATRAC3P_SUBBANDS, 1.0/1024);
/* append the result to the history */
for (i = 0; i < 8; i++) {
hist->buf1[hist->pos][i] = idct_out[i + 8];
hist->buf2[hist->pos][i] = idct_out[7 - i];
}
pos_now = hist->pos;
pos_next = mod23_lut[pos_now + 2]; // pos_next = (pos_now + 1) % 23;
for (t = 0; t < ATRAC3P_PQF_FIR_LEN; t++) {
for (i = 0; i < 8; i++) {
out[s * 16 + i + 0] += hist->buf1[pos_now][i] * ff_ipqf_coeffs1[t][i] +
hist->buf2[pos_next][i] * ff_ipqf_coeffs2[t][i];
out[s * 16 + i + 8] += hist->buf1[pos_now][7 - i] * ff_ipqf_coeffs1[t][i + 8] +
hist->buf2[pos_next][7 - i] * ff_ipqf_coeffs2[t][i + 8];
}
pos_now = mod23_lut[pos_next + 2]; // pos_now = (pos_now + 2) % 23;
pos_next = mod23_lut[pos_now + 2]; // pos_next = (pos_next + 2) % 23;
}
hist->pos = mod23_lut[hist->pos]; // hist->pos = (hist->pos - 1) % 23;
}
}
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