ref: 4041be70bf23c172dda3d107e19d84c2fb58f644
dir: /libfaad/codebook/hcb.h/
/*
** FAAD - Freeware Advanced Audio Decoder
** Copyright (C) 2002 M. Bakker
**
** 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: hcb.h,v 1.2 2002/02/18 10:01:05 menno Exp $
**/
#ifndef __HCB_H__
#define __HCB_H__
#ifdef __cplusplus
extern "C" {
#endif
/*
* Optimal huffman decoding for AAC taken from:
* "SELECTING AN OPTIMAL HUFFMAN DECODER FOR AAC" by
* VLADIMIR Z. MESAROVIC , RAGHUNATH RAO, MIROSLAV V. DOKIC, and SACHIN DEO
* AES paper 5436
*
* 2 methods are used for huffman decoding:
* - binary search
* - 2-step table lookup
*
* The choice of the "optimal" method is based on the fact that if the
* memory size for the Two-step is exorbitantly high then the decision
* is Binary search for that codebook. However, for marginally more memory
* size, if Twostep outperforms even the best case of Binary then the
* decision is Two-step for that codebook.
*
* The following methods are used for the different tables.
* codebook "optimal" method
* HCB_1 2-Step
* HCB_2 2-Step
* HCB_3 Binary
* HCB_4 2-Step
* HCB_5 Binary
* HCB_6 2-Step
* HCB_7 Binary
* HCB_8 2-Step
* HCB_9 Binary
* HCB_10 2-Step
* HCB_11 2-Step
* HCB_SF Binary
*
*/
#define ZERO_HCB 0
#define FIRST_PAIR_HCB 5
#define ESC_HCB 11
#define QUAD_LEN 4
#define PAIR_LEN 2
#define NSPECBOOKS ESC_HCB + 1
#define BOOKSCL NSPECBOOKS
#define NOISE_HCB 13
#define INTENSITY_HCB2 14
#define INTENSITY_HCB 15
/* 1st step table */
typedef struct
{
uint8_t offset;
uint8_t extra_bits;
} hcb;
/* 2nd step table with quadruple data */
typedef struct
{
uint8_t bits;
int8_t x;
int8_t y;
} hcb_2_pair;
typedef struct
{
uint8_t bits;
int8_t x;
int8_t y;
int8_t v;
int8_t w;
} hcb_2_quad;
/* binary search table */
typedef struct
{
uint8_t is_leaf;
int8_t data[4];
} hcb_bin_quad;
typedef struct
{
uint8_t is_leaf;
int8_t data[2];
} hcb_bin_pair;
extern hcb hcb1_1[];
extern hcb hcb2_1[];
extern hcb hcb4_1[];
extern hcb hcb6_1[];
extern hcb hcb8_1[];
extern hcb hcb10_1[];
extern hcb hcb11_1[];
extern hcb_2_quad hcb1_2[];
extern hcb_2_quad hcb2_2[];
extern hcb_2_quad hcb4_2[];
extern hcb_2_pair hcb6_2[];
extern hcb_2_pair hcb8_2[];
extern hcb_2_pair hcb10_2[];
extern hcb_2_pair hcb11_2[];
extern hcb_bin_quad hcb3[];
extern hcb_bin_pair hcb5[];
extern hcb_bin_pair hcb7[];
extern hcb_bin_pair hcb9[];
extern uint8_t hcb_sf[][2];
#ifdef __cplusplus
}
#endif
#endif