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/**
* Flake: FLAC audio encoder
* Copyright (c) 2006 Justin Ruggles
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file rice.c
* Functions for calculating optimal partition order and Rice parameters
*/
#include "common.h"
#include "rice.h"
int
find_optimal_rice_param(uint32_t sum, int n)
{
int k, k_opt;
uint32_t nbits[MAX_RICE_PARAM+1];
k_opt = 0;
nbits[0] = UINT32_MAX;
for(k=0; k<=MAX_RICE_PARAM; k++) {
nbits[k] = rice_encode_count(sum, n, k);
if(nbits[k] < nbits[k_opt]) {
k_opt = k;
}
}
return k_opt;
}
static uint32_t
calc_optimal_rice_params(RiceContext *rc, int porder, uint32_t *sums,
int n, int pred_order)
{
int i;
int k, cnt, part;
uint32_t all_bits;
part = (1 << porder);
all_bits = 0;
cnt = (n >> porder) - pred_order;
for(i=0; i<part; i++) {
if(i == 1) cnt = (n >> porder);
k = find_optimal_rice_param(sums[i], cnt);
rc->params[i] = k;
all_bits += rice_encode_count(sums[i], cnt, k);
}
all_bits += (4 * part);
rc->porder = porder;
return all_bits;
}
static void
calc_sums(int pmin, int pmax, uint32_t *data, int n, int pred_order,
uint32_t sums[][MAX_PARTITIONS])
{
int i, j;
int parts, cnt;
uint32_t *res;
// sums for highest level
parts = (1 << pmax);
res = &data[pred_order];
cnt = (n >> pmax) - pred_order;
for(i=0; i<parts; i++) {
if(i == 1) cnt = (n >> pmax);
if(i > 0) res = &data[i*cnt];
sums[pmax][i] = 0;
for(j=0; j<cnt; j++) {
sums[pmax][i] += res[j];
}
}
// sums for lower levels
for(i=pmax-1; i>=pmin; i--) {
parts = (1 << i);
for(j=0; j<parts; j++) {
sums[i][j] = sums[i+1][2*j] + sums[i+1][2*j+1];
}
}
}
static uint32_t
calc_rice_params(RiceContext *rc, int pmin, int pmax, int32_t *data, int n,
int pred_order)
{
int i;
uint32_t bits[MAX_PARTITION_ORDER+1];
int opt_porder;
RiceContext tmp_rc;
uint32_t *udata;
uint32_t sums[MAX_PARTITION_ORDER+1][MAX_PARTITIONS];
assert(pmin >= 0 && pmin <= MAX_PARTITION_ORDER);
assert(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
assert(pmin <= pmax);
udata = malloc(n * sizeof(uint32_t));
for(i=0; i<n; i++) {
udata[i] = (2*data[i]) ^ (data[i]>>31);
}
calc_sums(pmin, pmax, udata, n, pred_order, sums);
opt_porder = pmin;
bits[pmin] = UINT32_MAX;
for(i=pmin; i<=pmax; i++) {
bits[i] = calc_optimal_rice_params(&tmp_rc, i, sums[i], n, pred_order);
if(bits[i] <= bits[opt_porder]) {
opt_porder = i;
*rc = tmp_rc;
}
}
free(udata);
return bits[opt_porder];
}
static int
get_max_p_order(int max_porder, int n, int order)
{
int porder = MIN(max_porder, log2i(n^(n-1)));
if(order > 0)
porder = MIN(porder, log2i(n/order));
return porder;
}
uint32_t
calc_rice_params_fixed(RiceContext *rc, int pmin, int pmax, int32_t *data,
int n, int pred_order, int bps)
{
uint32_t bits;
pmin = get_max_p_order(pmin, n, pred_order);
pmax = get_max_p_order(pmax, n, pred_order);
bits = pred_order*bps + 6;
bits += calc_rice_params(rc, pmin, pmax, data, n, pred_order);
return bits;
}
uint32_t
calc_rice_params_lpc(RiceContext *rc, int pmin, int pmax, int32_t *data, int n,
int pred_order, int bps, int precision)
{
uint32_t bits;
pmin = get_max_p_order(pmin, n, pred_order);
pmax = get_max_p_order(pmax, n, pred_order);
bits = pred_order*bps + 4 + 5 + pred_order*precision + 6;
bits += calc_rice_params(rc, pmin, pmax, data, n, pred_order);
return bits;
}
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