Codebook Generator using the ELBG algorithm. More...

#include <string.h>
#include "libavutil/avassert.h"
#include "libavutil/common.h"
#include "libavutil/lfg.h"
#include "elbg.h"
#include "avcodec.h"

Data Structures
struct	cell
	In the ELBG jargon, a cell is the set of points that are closest to a codebook entry. More...

struct	elbg_data
	ELBG internal data. More...

Macros
#define	DELTA_ERR_MAX 0.1
	Precision of the ELBG algorithm (as percentage error) More...

#define	BIG_PRIME 433494437LL

Functions
static int	distance_limited (int a, int b, int dim, int limit)

static void	vect_division (int res, int vect, int div, int dim)

static int	eval_error_cell (elbg_data elbg, int centroid, cell *cells)

static int	get_closest_codebook (elbg_data *elbg, int index)

static int	get_high_utility_cell (elbg_data *elbg)

static int	simple_lbg (elbg_data elbg, int dim, int centroid[3], int newutility[3], int points, cell cells)
	Implementation of the simple LBG algorithm for just two codebooks. More...

static void	get_new_centroids (elbg_data elbg, int huc, int newcentroid_i, int *newcentroid_p)

static void	shift_codebook (elbg_data elbg, int indexes, int *newcentroid[3])
	Add the points in the low utility cell to its closest cell. More...

static void	evaluate_utility_inc (elbg_data *elbg)

static void	update_utility_and_n_cb (elbg_data *elbg, int idx, int newutility)

static void	try_shift_candidate (elbg_data *elbg, int idx[3])
	Evaluate if a shift lower the error. More...

static void	do_shiftings (elbg_data *elbg)
	Implementation of the ELBG block. More...

int	avpriv_init_elbg (int points, int dim, int numpoints, int codebook, int numCB, int max_steps, int closest_cb, AVLFG rand_state)
	Initialize the **codebook vector for the elbg algorithm. More...

int	avpriv_do_elbg (int points, int dim, int numpoints, int codebook, int numCB, int max_steps, int closest_cb, AVLFG rand_state)
	Implementation of the Enhanced LBG Algorithm Based on the paper "Neural Networks 14:1219-1237" that can be found in http://citeseer.ist.psu.edu/patan01enhanced.html . More...

Detailed Description

Codebook Generator using the ELBG algorithm.

Definition in file elbg.c.

Macro Definition Documentation

#define DELTA_ERR_MAX 0.1

Precision of the ELBG algorithm (as percentage error)

Definition at line 34 of file elbg.c.

Referenced by avpriv_do_elbg().

#define BIG_PRIME 433494437LL

Definition at line 335 of file elbg.c.

Referenced by avpriv_init_elbg().

Function Documentation

static int distance_limited	(	int *	a,
		int *	b,
		int	dim,
		int	limit
	)

inlinestatic

Definition at line 61 of file elbg.c.

Referenced by avpriv_do_elbg(), eval_error_cell(), get_closest_codebook(), shift_codebook(), and simple_lbg().

static void vect_division	(	int *	res,
		int *	vect,
		int	div,
		int	dim
	)

inlinestatic

Definition at line 73 of file elbg.c.

Referenced by avpriv_do_elbg(), simple_lbg(), and try_shift_candidate().

static int eval_error_cell	(	elbg_data *	elbg,
		int *	centroid,
		cell *	cells
	)

static

Definition at line 84 of file elbg.c.

Referenced by try_shift_candidate().

static int get_closest_codebook	(	elbg_data *	elbg,
		int	index
	)

static

Definition at line 93 of file elbg.c.

Referenced by do_shiftings().

static int get_high_utility_cell ( elbg_data * elbg )

static

Definition at line 107 of file elbg.c.

Referenced by do_shiftings().

static int simple_lbg	(	elbg_data *	elbg,
		int	dim,
		int *	centroid[3],
		int	newutility[3],
		int *	points,
		cell *	cells
	)

static

Implementation of the simple LBG algorithm for just two codebooks.

Definition at line 132 of file elbg.c.

Referenced by try_shift_candidate().

static void get_new_centroids	(	elbg_data *	elbg,
		int	huc,
		int *	newcentroid_i,
		int *	newcentroid_p
	)

static

Definition at line 173 of file elbg.c.

Referenced by try_shift_candidate().

static void shift_codebook	(	elbg_data *	elbg,
		int *	indexes,
		int *	newcentroid[3]
	)

static

Add the points in the low utility cell to its closest cell.

Split the high utility cell, putting the separated points in the (now empty) low utility cell.

Parameters

elbg	Internal elbg data
indexes	{luc, huc, cluc}
newcentroid	A vector with the position of the new centroids

Definition at line 209 of file elbg.c.

Referenced by try_shift_candidate().

static void evaluate_utility_inc ( elbg_data * elbg )

static

Definition at line 237 of file elbg.c.

Referenced by do_shiftings(), and try_shift_candidate().

static void update_utility_and_n_cb	(	elbg_data *	elbg,
		int	idx,
		int	newutility
	)

static

Definition at line 250 of file elbg.c.

Referenced by try_shift_candidate().

static void try_shift_candidate	(	elbg_data *	elbg,
		int	idx[3]
	)

static

Evaluate if a shift lower the error.

If it does, call shift_codebooks and update elbg->error, elbg->utility and elbg->nearest_cb.

Parameters

elbg	Internal elbg data
idx	{luc (low utility cell, huc (high utility cell), cluc (closest cell to low utility cell)}

Definition at line 266 of file elbg.c.

Referenced by do_shiftings().

static void do_shiftings ( elbg_data * elbg )

static

Implementation of the ELBG block.

Definition at line 316 of file elbg.c.

Referenced by avpriv_do_elbg().

int avpriv_init_elbg	(	int *	points,
		int	dim,
		int	numpoints,
		int *	codebook,
		int	numCB,
		int	num_steps,
		int *	closest_cb,
		AVLFG *	rand_state
	)

Initialize the **codebook vector for the elbg algorithm.

If you have already a codebook and you want to refine it, you shouldn't call this function. If numpoints < 8*numCB this function fills **codebook with random numbers. If not, it calls avpriv_do_elbg for a (smaller) random sample of the points in **points. Get the same parameters as avpriv_do_elbg.

Returns: < 0 in case of error, 0 otherwise

Definition at line 337 of file elbg.c.

Referenced by a64multi_encode_frame(), avpriv_init_elbg(), encode_frame(), filter_frame(), generate_codebook(), and quantize().

int avpriv_do_elbg	(	int *	points,
		int	dim,
		int	numpoints,
		int *	codebook,
		int	numCB,
		int	num_steps,
		int *	closest_cb,
		AVLFG *	rand_state
	)

Implementation of the Enhanced LBG Algorithm Based on the paper "Neural Networks 14:1219-1237" that can be found in http://citeseer.ist.psu.edu/patan01enhanced.html .

Parameters

points	Input points.
dim	Dimension of the points.
numpoints	Num of points in **points.
codebook	Pointer to the output codebook. Must be allocated.
numCB	Number of points in the codebook.
num_steps	The maximum number of steps. One step is already a good compromise between time and quality.
closest_cb	Return the closest codebook to each point. Must be allocated.
rand_state	A random number generator state. Should be already initialized by av_lfg_init().

Returns: < 0 in case of error, 0 otherwise

Definition at line 371 of file elbg.c.

Referenced by a64multi_encode_frame(), avpriv_init_elbg(), encode_frame(), filter_frame(), generate_codebook(), and quantize().

Data Structures

Macros

Functions

Detailed Description

Macro Definition Documentation

Function Documentation