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.
static uint8_t *	bgmc_lut_getp (uint8_t *lut, int *lut_status, int delta)
	Retune the index of a suitable lookup table for a given delta.
av_cold int	ff_bgmc_init (AVCodecContext *avctx, uint8_t **cf_lut, int **cf_lut_status)
	Initialize the lookup table arrays.
av_cold void	ff_bgmc_end (uint8_t **cf_lut, int **cf_lut_status)
	Release the lookup table arrays.
void	ff_bgmc_decode_init (GetBitContext *gb, unsigned int *h, unsigned int *l, unsigned int *v)
	Initialize decoding and reads the first value.
void	ff_bgmc_decode_end (GetBitContext *gb)
	Finish decoding.
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.

Variables
static const uint16_t	cf_tables_1 [3][129]
	Cumulative frequency tables for block Gilbert-Moore coding.
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 googlemail.com>

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)

Definition at line 38 of file bgmc.c.

Referenced by bgmc_lut_fillp(), and ff_bgmc_decode().

#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().

void 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 498 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 505 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]
}

Definition at line 417 of file bgmc.c.

Referenced by bgmc_lut_fillp(), and ff_bgmc_decode().