FFmpeg
Macros | Functions | Variables
bgmc.c File Reference

Block Gilbert-Moore decoder as used by MPEG-4 ALS. More...

#include "libavutil/attributes.h"
#include "bgmc.h"

Go to the source code of this file.

Macros

#define FREQ_BITS   14
 
#define VALUE_BITS   18
 
#define TOP_VALUE   ((1 << VALUE_BITS) - 1)
 
#define FIRST_QTR   (TOP_VALUE / 4 + 1)
 
#define HALF   (2 * FIRST_QTR)
 
#define THIRD_QTR   (3 * FIRST_QTR)
 
#define LUT_BITS   (FREQ_BITS - 8)
 
#define LUT_SIZE   (1 << LUT_BITS)
 
#define LUT_BUFF   4
 

Functions

static void bgmc_lut_fillp (uint8_t *lut, int *lut_status, int delta)
 Initialize a given lookup table using a given delta. More...
 
static uint8_tbgmc_lut_getp (uint8_t *lut, int *lut_status, int delta)
 Retune the index of a suitable lookup table for a given delta. More...
 
av_cold int ff_bgmc_init (AVCodecContext *avctx, uint8_t **cf_lut, int **cf_lut_status)
 Initialize the lookup table arrays. More...
 
av_cold void ff_bgmc_end (uint8_t **cf_lut, int **cf_lut_status)
 Release the lookup table arrays. More...
 
int ff_bgmc_decode_init (GetBitContext *gb, unsigned int *h, unsigned int *l, unsigned int *v)
 Initialize decoding and reads the first value. More...
 
void ff_bgmc_decode_end (GetBitContext *gb)
 Finish decoding. More...
 
void ff_bgmc_decode (GetBitContext *gb, unsigned int num, int32_t *dst, int delta, unsigned int sx, unsigned int *h, unsigned int *l, unsigned int *v, uint8_t *cf_lut, int *cf_lut_status)
 Read and decode a block Gilbert-Moore coded symbol. More...
 

Variables

static const uint16_t cf_tables_1 [3][129]
 Cumulative frequency tables for block Gilbert-Moore coding. More...
 
static const uint16_t cf_tables_2 [8][193]
 
static const uint16_t cf_tables_3 [5][257]
 
static const uint16_t *const cf_table [16]
 

Detailed Description

Block Gilbert-Moore decoder as used by MPEG-4 ALS.

Author
Thilo Borgmann <thilo.borgmann at mail.de>

Definition in file bgmc.c.

Macro Definition Documentation

#define FREQ_BITS   14

Definition at line 31 of file bgmc.c.

Referenced by bgmc_lut_fillp(), and ff_bgmc_decode().

#define VALUE_BITS   18

Definition at line 32 of file bgmc.c.

Referenced by ff_bgmc_decode_end(), and ff_bgmc_decode_init().

#define TOP_VALUE   ((1 << VALUE_BITS) - 1)

Definition at line 33 of file bgmc.c.

Referenced by ff_bgmc_decode_init().

#define FIRST_QTR   (TOP_VALUE / 4 + 1)

Definition at line 34 of file bgmc.c.

Referenced by ff_bgmc_decode().

#define HALF   (2 * FIRST_QTR)

Definition at line 35 of file bgmc.c.

Referenced by ff_bgmc_decode().

#define THIRD_QTR   (3 * FIRST_QTR)

Definition at line 36 of file bgmc.c.

Referenced by ff_bgmc_decode().

#define LUT_BITS   (FREQ_BITS - 8)
#define LUT_SIZE   (1 << LUT_BITS)

Definition at line 39 of file bgmc.c.

Referenced by bgmc_lut_fillp(), bgmc_lut_getp(), ff_bgmc_decode(), and ff_bgmc_init().

#define LUT_BUFF   4

Definition at line 40 of file bgmc.c.

Referenced by bgmc_lut_getp(), and ff_bgmc_init().

Function Documentation

static void bgmc_lut_fillp ( uint8_t lut,
int lut_status,
int  delta 
)
static

Initialize a given lookup table using a given delta.

Definition at line 426 of file bgmc.c.

Referenced by bgmc_lut_getp().

static uint8_t* bgmc_lut_getp ( uint8_t lut,
int lut_status,
int  delta 
)
static

Retune the index of a suitable lookup table for a given delta.

Definition at line 446 of file bgmc.c.

Referenced by ff_bgmc_decode().

av_cold int ff_bgmc_init ( AVCodecContext avctx,
uint8_t **  cf_lut,
int **  cf_lut_status 
)

Initialize the lookup table arrays.

Definition at line 460 of file bgmc.c.

Referenced by decode_init().

av_cold void ff_bgmc_end ( uint8_t **  cf_lut,
int **  cf_lut_status 
)

Release the lookup table arrays.

Definition at line 480 of file bgmc.c.

Referenced by decode_end(), and ff_bgmc_init().

int ff_bgmc_decode_init ( GetBitContext gb,
unsigned int h,
unsigned int l,
unsigned int v 
)

Initialize decoding and reads the first value.

Definition at line 488 of file bgmc.c.

Referenced by read_var_block_data().

void ff_bgmc_decode_end ( GetBitContext gb)

Finish decoding.

Definition at line 503 of file bgmc.c.

Referenced by read_var_block_data().

void ff_bgmc_decode ( GetBitContext gb,
unsigned int  num,
int32_t dst,
int  delta,
unsigned int  sx,
unsigned int h,
unsigned int l,
unsigned int v,
uint8_t cf_lut,
int cf_lut_status 
)

Read and decode a block Gilbert-Moore coded symbol.

Definition at line 510 of file bgmc.c.

Referenced by read_var_block_data().

Variable Documentation

const uint16_t cf_tables_1[3][129]
static

Cumulative frequency tables for block Gilbert-Moore coding.

Definition at line 44 of file bgmc.c.

const uint16_t cf_tables_2[8][193]
static

Definition at line 93 of file bgmc.c.

const uint16_t cf_tables_3[5][257]
static

Definition at line 273 of file bgmc.c.

const uint16_t* const cf_table[16]
static
Initial value:
= {
cf_tables_1[0], cf_tables_1[1], cf_tables_1[2], cf_tables_2[0],
cf_tables_2[1], cf_tables_2[2], cf_tables_2[3], cf_tables_2[4],
cf_tables_2[5], cf_tables_2[6], cf_tables_2[7], cf_tables_3[0],
cf_tables_3[1], cf_tables_3[2], cf_tables_3[3], cf_tables_3[4]
}
static const uint16_t cf_tables_1[3][129]
Cumulative frequency tables for block Gilbert-Moore coding.
Definition: bgmc.c:44
static const uint16_t cf_tables_3[5][257]
Definition: bgmc.c:273
static const uint16_t cf_tables_2[8][193]
Definition: bgmc.c:93

Definition at line 417 of file bgmc.c.

Referenced by bgmc_lut_fillp(), and ff_bgmc_decode().