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FFmpeg/libavcodec/ac3dsp.c
Nedeljko Babic 696e34a6e1 libavcodec: Implementation of AC3 fixedpoint decoder 
Signed-off-by: Nedeljko Babic <nbabic@mips.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2014-04-01 19:01:57 +02:00

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/*
* AC-3 DSP functions
* Copyright (c) 2011 Justin Ruggles
*
* 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
*/
#include "libavutil/avassert.h"
#include "avcodec.h"
#include "ac3.h"
#include "ac3dsp.h"
#include "mathops.h"
static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
{
int blk, i;
if (!num_reuse_blocks)
return;
for (i = 0; i < nb_coefs; i++) {
uint8_t min_exp = *exp;
uint8_t *exp1 = exp + 256;
for (blk = 0; blk < num_reuse_blocks; blk++) {
uint8_t next_exp = *exp1;
if (next_exp < min_exp)
min_exp = next_exp;
exp1 += 256;
}
*exp++ = min_exp;
}
}
static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
{
int i, v = 0;
for (i = 0; i < len; i++)
v |= abs(src[i]);
return v;
}
static void ac3_lshift_int16_c(int16_t *src, unsigned int len,
unsigned int shift)
{
uint32_t *src32 = (uint32_t *)src;
const uint32_t mask = ~(((1 << shift) - 1) << 16);
int i;
len >>= 1;
for (i = 0; i < len; i += 8) {
src32[i ] = (src32[i ] << shift) & mask;
src32[i+1] = (src32[i+1] << shift) & mask;
src32[i+2] = (src32[i+2] << shift) & mask;
src32[i+3] = (src32[i+3] << shift) & mask;
src32[i+4] = (src32[i+4] << shift) & mask;
src32[i+5] = (src32[i+5] << shift) & mask;
src32[i+6] = (src32[i+6] << shift) & mask;
src32[i+7] = (src32[i+7] << shift) & mask;
}
}
static void ac3_rshift_int32_c(int32_t *src, unsigned int len,
unsigned int shift)
{
do {
*src++ >>= shift;
*src++ >>= shift;
*src++ >>= shift;
*src++ >>= shift;
*src++ >>= shift;
*src++ >>= shift;
*src++ >>= shift;
*src++ >>= shift;
len -= 8;
} while (len > 0);
}
static void float_to_fixed24_c(int32_t *dst, const float *src, unsigned int len)
{
const float scale = 1 << 24;
do {
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
*dst++ = lrintf(*src++ * scale);
len -= 8;
} while (len > 0);
}
static void ac3_bit_alloc_calc_bap_c(int16_t *mask, int16_t *psd,
int start, int end,
int snr_offset, int floor,
const uint8_t *bap_tab, uint8_t *bap)
{
int bin, band, band_end;
/* special case, if snr offset is -960, set all bap's to zero */
if (snr_offset == -960) {
memset(bap, 0, AC3_MAX_COEFS);
return;
}
bin = start;
band = ff_ac3_bin_to_band_tab[start];
do {
int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
band_end = ff_ac3_band_start_tab[++band];
band_end = FFMIN(band_end, end);
for (; bin < band_end; bin++) {
int address = av_clip((psd[bin] - m) >> 5, 0, 63);
bap[bin] = bap_tab[address];
}
} while (end > band_end);
}
static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
int len)
{
while (len-- > 0)
mant_cnt[bap[len]]++;
}
DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
0, 0, 0, 3, 0, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
};
static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
{
int blk, bap;
int bits = 0;
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
// bap=1 : 3 mantissas in 5 bits
bits += (mant_cnt[blk][1] / 3) * 5;
// bap=2 : 3 mantissas in 7 bits
// bap=4 : 2 mantissas in 7 bits
bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
// bap=3 : 1 mantissa in 3 bits
bits += mant_cnt[blk][3] * 3;
// bap=5 to 15 : get bits per mantissa from table
for (bap = 5; bap < 16; bap++)
bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];
}
return bits;
}
static void ac3_extract_exponents_c(uint8_t *exp, int32_t *coef, int nb_coefs)
{
int i;
for (i = 0; i < nb_coefs; i++) {
int v = abs(coef[i]);
exp[i] = v ? 23 - av_log2(v) : 24;
}
}
static void ac3_sum_square_butterfly_int32_c(int64_t sum[4],
const int32_t *coef0,
const int32_t *coef1,
int len)
{
int i;
sum[0] = sum[1] = sum[2] = sum[3] = 0;
for (i = 0; i < len; i++) {
int lt = coef0[i];
int rt = coef1[i];
int md = lt + rt;
int sd = lt - rt;
MAC64(sum[0], lt, lt);
MAC64(sum[1], rt, rt);
MAC64(sum[2], md, md);
MAC64(sum[3], sd, sd);
}
}
static void ac3_sum_square_butterfly_float_c(float sum[4],
const float *coef0,
const float *coef1,
int len)
{
int i;
sum[0] = sum[1] = sum[2] = sum[3] = 0;
for (i = 0; i < len; i++) {
float lt = coef0[i];
float rt = coef1[i];
float md = lt + rt;
float sd = lt - rt;
sum[0] += lt * lt;
sum[1] += rt * rt;
sum[2] += md * md;
sum[3] += sd * sd;
}
}
static void ac3_downmix_c(float **samples, float (*matrix)[2],
int out_ch, int in_ch, int len)
{
int i, j;
float v0, v1;
if (out_ch == 2) {
for (i = 0; i < len; i++) {
v0 = v1 = 0.0f;
for (j = 0; j < in_ch; j++) {
v0 += samples[j][i] * matrix[j][0];
v1 += samples[j][i] * matrix[j][1];
}
samples[0][i] = v0;
samples[1][i] = v1;
}
} else if (out_ch == 1) {
for (i = 0; i < len; i++) {
v0 = 0.0f;
for (j = 0; j < in_ch; j++)
v0 += samples[j][i] * matrix[j][0];
samples[0][i] = v0;
}
}
}
static void ac3_downmix_c_fixed(int32_t **samples, int16_t (*matrix)[2],
int out_ch, int in_ch, int len)
{
int i, j;
int64_t v0, v1;
if (out_ch == 2) {
for (i = 0; i < len; i++) {
v0 = v1 = 0;
for (j = 0; j < in_ch; j++) {
v0 += (int64_t)samples[j][i] * matrix[j][0];
v1 += (int64_t)samples[j][i] * matrix[j][1];
}
samples[0][i] = (v0+2048)>>12;
samples[1][i] = (v1+2048)>>12;
}
} else if (out_ch == 1) {
for (i = 0; i < len; i++) {
v0 = 0;
for (j = 0; j < in_ch; j++)
v0 += (int64_t)samples[j][i] * matrix[j][0];
samples[0][i] = (v0+2048)>>12;
}
}
}
static void apply_window_int16_c(int16_t *output, const int16_t *input,
const int16_t *window, unsigned int len)
{
int i;
int len2 = len >> 1;
for (i = 0; i < len2; i++) {
int16_t w = window[i];
output[i] = (MUL16(input[i], w) + (1 << 14)) >> 15;
output[len-i-1] = (MUL16(input[len-i-1], w) + (1 << 14)) >> 15;
}
}
av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)
{
c->ac3_exponent_min = ac3_exponent_min_c;
c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
c->ac3_lshift_int16 = ac3_lshift_int16_c;
c->ac3_rshift_int32 = ac3_rshift_int32_c;
c->float_to_fixed24 = float_to_fixed24_c;
c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;
c->update_bap_counts = ac3_update_bap_counts_c;
c->compute_mantissa_size = ac3_compute_mantissa_size_c;
c->extract_exponents = ac3_extract_exponents_c;
c->sum_square_butterfly_int32 = ac3_sum_square_butterfly_int32_c;
c->sum_square_butterfly_float = ac3_sum_square_butterfly_float_c;
c->downmix = ac3_downmix_c;
c->downmix_fixed = ac3_downmix_c_fixed;
c->apply_window_int16 = apply_window_int16_c;
if (ARCH_ARM)
ff_ac3dsp_init_arm(c, bit_exact);
if (ARCH_X86)
ff_ac3dsp_init_x86(c, bit_exact);
if (ARCH_MIPS)
ff_ac3dsp_init_mips(c, bit_exact);
}
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