mbcoding.c

这是一个压缩解压包,用C语言进行编程的,里面有详细的源代码.

/*****************************************************************************
 *
 *  XVID MPEG-4 VIDEO CODEC
 *  - MB coding -
 *
 *  Copyright (C) 2002 Michael Militzer <[e-mail]>
 *
 *  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: mbcoding.c,v 1.52.2.2 2007/06/28 15:00:11 Isibaar Exp $
 *
 ****************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../portab.h"
#include "../global.h"
#include "bitstream.h"
#include "zigzag.h"
#include "vlc_codes.h"
#include "mbcoding.h"

#include "../utils/mbfunctions.h"

#define LEVELOFFSET 32

/* Initialized once during xvid_global call
 * RO access is thread safe */
static REVERSE_EVENT DCT3D[2][4096];
static VLC coeff_VLC[2][2][64][64];

/* not really MB related, but VLCs are only available here */
void bs_put_spritetrajectory(Bitstream * bs, const int val)
{
	const int code = sprite_trajectory_code[val+16384].code;
	const int len = sprite_trajectory_code[val+16384].len;
	const int code2 = sprite_trajectory_len[len].code;
	const int len2 = sprite_trajectory_len[len].len;

#if 0
	printf("GMC=%d Code/Len  = %d / %d ",val, code,len);
	printf("Code2 / Len2 = %d / %d \n",code2,len2);
#endif

	BitstreamPutBits(bs, code2, len2);
	if (len) BitstreamPutBits(bs, code, len);
}

int bs_get_spritetrajectory(Bitstream * bs)
{
	int i;
	for (i = 0; i < 12; i++)
	{
		if (BitstreamShowBits(bs, sprite_trajectory_len[i].len) == sprite_trajectory_len[i].code)
		{
			BitstreamSkip(bs, sprite_trajectory_len[i].len);
			return i;
		}
	}
	return -1;
}

void
init_vlc_tables(void)
{
	uint32_t i, j, k, intra, last, run,  run_esc, level, level_esc, escape, escape_len, offset;
	int32_t l;

	for (intra = 0; intra < 2; intra++)
		for (i = 0; i < 4096; i++)
			DCT3D[intra][i].event.level = 0;

	for (intra = 0; intra < 2; intra++) {
		for (last = 0; last < 2; last++) {
			for (run = 0; run < 63 + last; run++) {
				for (level = 0; level < (uint32_t)(32 << intra); level++) {
					offset = !intra * LEVELOFFSET;
					coeff_VLC[intra][last][level + offset][run].len = 128;
				}
			}
		}
	}

	for (intra = 0; intra < 2; intra++) {
		for (i = 0; i < 102; i++) {
			offset = !intra * LEVELOFFSET;

			for (j = 0; j < (uint32_t)(1 << (12 - coeff_tab[intra][i].vlc.len)); j++) {
				DCT3D[intra][(coeff_tab[intra][i].vlc.code << (12 - coeff_tab[intra][i].vlc.len)) | j].len	 = coeff_tab[intra][i].vlc.len;
				DCT3D[intra][(coeff_tab[intra][i].vlc.code << (12 - coeff_tab[intra][i].vlc.len)) | j].event = coeff_tab[intra][i].event;
			}

			coeff_VLC[intra][coeff_tab[intra][i].event.last][coeff_tab[intra][i].event.level + offset][coeff_tab[intra][i].event.run].code
				= coeff_tab[intra][i].vlc.code << 1;
			coeff_VLC[intra][coeff_tab[intra][i].event.last][coeff_tab[intra][i].event.level + offset][coeff_tab[intra][i].event.run].len
				= coeff_tab[intra][i].vlc.len + 1;

			if (!intra) {
				coeff_VLC[intra][coeff_tab[intra][i].event.last][offset - coeff_tab[intra][i].event.level][coeff_tab[intra][i].event.run].code
					= (coeff_tab[intra][i].vlc.code << 1) | 1;
				coeff_VLC[intra][coeff_tab[intra][i].event.last][offset - coeff_tab[intra][i].event.level][coeff_tab[intra][i].event.run].len
					= coeff_tab[intra][i].vlc.len + 1;
			}
		}
	}

	for (intra = 0; intra < 2; intra++) {
		for (last = 0; last < 2; last++) {
			for (run = 0; run < 63 + last; run++) {
				for (level = 1; level < (uint32_t)(32 << intra); level++) {

					if (level <= max_level[intra][last][run] && run <= max_run[intra][last][level])
					    continue;

					offset = !intra * LEVELOFFSET;
                    level_esc = level - max_level[intra][last][run];
					run_esc = run - 1 - max_run[intra][last][level];

					if (level_esc <= max_level[intra][last][run] && run <= max_run[intra][last][level_esc]) {
						escape     = ESCAPE1;
						escape_len = 7 + 1;
						run_esc    = run;
					} else {
						if (run_esc <= max_run[intra][last][level] && level <= max_level[intra][last][run_esc]) {
							escape     = ESCAPE2;
							escape_len = 7 + 2;
							level_esc  = level;
						} else {
							if (!intra) {
								coeff_VLC[intra][last][level + offset][run].code
									= (ESCAPE3 << 21) | (last << 20) | (run << 14) | (1 << 13) | ((level & 0xfff) << 1) | 1;
								coeff_VLC[intra][last][level + offset][run].len = 30;
									coeff_VLC[intra][last][offset - level][run].code
									= (ESCAPE3 << 21) | (last << 20) | (run << 14) | (1 << 13) | ((-(int32_t)level & 0xfff) << 1) | 1;
								coeff_VLC[intra][last][offset - level][run].len = 30;
							}
							continue;
						}
					}

					coeff_VLC[intra][last][level + offset][run].code
						= (escape << coeff_VLC[intra][last][level_esc + offset][run_esc].len)
						|  coeff_VLC[intra][last][level_esc + offset][run_esc].code;
					coeff_VLC[intra][last][level + offset][run].len
						= coeff_VLC[intra][last][level_esc + offset][run_esc].len + escape_len;

					if (!intra) {
						coeff_VLC[intra][last][offset - level][run].code
							= (escape << coeff_VLC[intra][last][level_esc + offset][run_esc].len)
							|  coeff_VLC[intra][last][level_esc + offset][run_esc].code | 1;
						coeff_VLC[intra][last][offset - level][run].len
							= coeff_VLC[intra][last][level_esc + offset][run_esc].len + escape_len;
					}
				}

				if (!intra) {
					coeff_VLC[intra][last][0][run].code
						= (ESCAPE3 << 21) | (last << 20) | (run << 14) | (1 << 13) | ((-32 & 0xfff) << 1) | 1;
					coeff_VLC[intra][last][0][run].len = 30;
				}
			}
		}
	}

	/* init sprite_trajectory tables
	 * even if GMC is not specified (it might be used later...) */

	sprite_trajectory_code[0+16384].code = 0;
	sprite_trajectory_code[0+16384].len = 0;
	for (k=0;k<14;k++) {
		int limit = (1<<k);

		for (l=-(2*limit-1); l <= -limit; l++) {
			sprite_trajectory_code[l+16384].code = (2*limit-1)+l;
			sprite_trajectory_code[l+16384].len = k+1;
		}

		for (l=limit; l<= 2*limit-1; l++) {
			sprite_trajectory_code[l+16384].code = l;
			sprite_trajectory_code[l+16384].len = k+1;
		}
	}
}

static __inline void
CodeVector(Bitstream * bs,
		   int32_t value,
		   int32_t f_code)
{

	const int scale_factor = 1 << (f_code - 1);
	const int cmp = scale_factor << 5;

	if (value < (-1 * cmp))
		value += 64 * scale_factor;

	if (value > (cmp - 1))
		value -= 64 * scale_factor;

	if (value == 0) {
		BitstreamPutBits(bs, mb_motion_table[32].code,
						 mb_motion_table[32].len);
	} else {
		uint16_t length, code, mv_res, sign;

		length = 16 << f_code;
		f_code--;

		sign = (value < 0);

		if (value >= length)
			value -= 2 * length;
		else if (value < -length)
			value += 2 * length;

		if (sign)
			value = -value;

		value--;
		mv_res = value & ((1 << f_code) - 1);
		code = ((value - mv_res) >> f_code) + 1;

		if (sign)
			code = -code;

		code += 32;
		BitstreamPutBits(bs, mb_motion_table[code].code,
						 mb_motion_table[code].len);

		if (f_code)
			BitstreamPutBits(bs, mv_res, f_code);
	}

}

static __inline void
CodeCoeffInter(Bitstream * bs,
		  const int16_t qcoeff[64],
		  const uint16_t * zigzag)
{
	uint32_t i, run, prev_run, code, len;
	int32_t level, prev_level, level_shifted;

	i	= 0;
	run = 0;

	while (!(level = qcoeff[zigzag[i++]]))
		run++;

	prev_level = level;
	prev_run   = run;
	run = 0;

	while (i < 64)
	{
		if ((level = qcoeff[zigzag[i++]]) != 0)
		{
			level_shifted = prev_level + 32;
			if (!(level_shifted & -64))
			{
				code = coeff_VLC[0][0][level_shifted][prev_run].code;
				len	 = coeff_VLC[0][0][level_shifted][prev_run].len;
			}
			else
			{
				code = (ESCAPE3 << 21) | (prev_run << 14) | (1 << 13) | ((prev_level & 0xfff) << 1) | 1;
				len  = 30;
			}
			BitstreamPutBits(bs, code, len);
			prev_level = level;
			prev_run   = run;
			run = 0;
		}
		else
			run++;
	}

	level_shifted = prev_level + 32;
	if (!(level_shifted & -64))
	{
		code = coeff_VLC[0][1][level_shifted][prev_run].code;
		len	 = coeff_VLC[0][1][level_shifted][prev_run].len;
	}
	else
	{
		code = (ESCAPE3 << 21) | (1 << 20) | (prev_run << 14) | (1 << 13) | ((prev_level & 0xfff) << 1) | 1;
		len  = 30;
	}
	BitstreamPutBits(bs, code, len);
}

static __inline void
CodeCoeffIntra(Bitstream * bs,
		  const int16_t qcoeff[64],
		  const uint16_t * zigzag)
{
	uint32_t i, abs_level, run, prev_run, code, len;
	int32_t level, prev_level;

	i	= 1;
	run = 0;

	while (i<64 && !(level = qcoeff[zigzag[i++]]))
		run++;

	prev_level = level;
	prev_run   = run;
	run = 0;

	while (i < 64)
	{
		if ((level = qcoeff[zigzag[i++]]) != 0)
		{
			abs_level = abs(prev_level);
			abs_level = abs_level < 64 ? abs_level : 0;
			code	  = coeff_VLC[1][0][abs_level][prev_run].code;
			len		  = coeff_VLC[1][0][abs_level][prev_run].len;
			if (len != 128)
				code |= (prev_level < 0);
			else
			{
		        code = (ESCAPE3 << 21) | (prev_run << 14) | (1 << 13) | ((prev_level & 0xfff) << 1) | 1;
				len  = 30;
			}
			BitstreamPutBits(bs, code, len);
			prev_level = level;
			prev_run   = run;
			run = 0;
		}
		else
			run++;
	}

	abs_level = abs(prev_level);
	abs_level = abs_level < 64 ? abs_level : 0;
	code	  = coeff_VLC[1][1][abs_level][prev_run].code;
	len		  = coeff_VLC[1][1][abs_level][prev_run].len;
	if (len != 128)
		code |= (prev_level < 0);
	else
	{
		code = (ESCAPE3 << 21) | (1 << 20) | (prev_run << 14) | (1 << 13) | ((prev_level & 0xfff) << 1) | 1;
		len  = 30;
	}
	BitstreamPutBits(bs, code, len);
}



/* returns the number of bits required to encode qcoeff */

int
CodeCoeffIntra_CalcBits(const int16_t qcoeff[64], const uint16_t * zigzag)
{
	int bits = 0;
	uint32_t i, abs_level, run, prev_run, len;
	int32_t level, prev_level;

	i	= 1;
	run = 0;

	while (i<64 && !(level = qcoeff[zigzag[i++]]))
		run++;

	if (i >= 64) return 0;	/* empty block */

	prev_level = level;
	prev_run   = run;
	run = 0;

	while (i < 64)
	{
		if ((level = qcoeff[zigzag[i++]]) != 0)
		{
			abs_level = abs(prev_level);
			abs_level = abs_level < 64 ? abs_level : 0;
			len		  = coeff_VLC[1][0][abs_level][prev_run].len;
			bits      += len!=128 ? len : 30;

			prev_level = level;
			prev_run   = run;
			run = 0;
		}
		else
			run++;
	}

	abs_level = abs(prev_level);
	abs_level = abs_level < 64 ? abs_level : 0;
	len		  = coeff_VLC[1][1][abs_level][prev_run].len;
	bits      += len!=128 ? len : 30;

	return bits;
}

int
CodeCoeffInter_CalcBits(const int16_t qcoeff[64], const uint16_t * zigzag)
{
	uint32_t i, run, prev_run, len;
	int32_t level, prev_level, level_shifted;
	int bits = 0;

	i	= 0;
	run = 0;

	while (!(level = qcoeff[zigzag[i++]]))
		run++;

	prev_level = level;
	prev_run   = run;
	run = 0;

	while (i < 64) {
		if ((level = qcoeff[zigzag[i++]]) != 0) {
			level_shifted = prev_level + 32;
			if (!(level_shifted & -64))
				len	 = coeff_VLC[0][0][level_shifted][prev_run].len;
			else
				len  = 30;

			bits += len;
			prev_level = level;
			prev_run   = run;
			run = 0;
		}
		else
			run++;
	}

	level_shifted = prev_level + 32;
	if (!(level_shifted & -64))
		len	 = coeff_VLC[0][1][level_shifted][prev_run].len;
	else
		len  = 30;
	bits += len;

	return bits;
}

static const int iDQtab[5] = {
	1, 0, -1 /* no change */, 2, 3
};
#define DQ_VALUE2INDEX(value)  iDQtab[(value)+2]


static __inline void
CodeBlockIntra(const FRAMEINFO * const frame,
			   const MACROBLOCK * pMB,
			   int16_t qcoeff[6 * 64],
			   Bitstream * bs,
			   Statistics * pStat)
{

	uint32_t i, mcbpc, cbpy, bits;

	cbpy = pMB->cbp >> 2;

	/* write mcbpc */
	if (frame->coding_type == I_VOP) {
		mcbpc = ((pMB->mode >> 1) & 3) | ((pMB->cbp & 3) << 2);
		BitstreamPutBits(bs, mcbpc_intra_tab[mcbpc].code,
						 mcbpc_intra_tab[mcbpc].len);
	} else {
		mcbpc = (pMB->mode & 7) | ((pMB->cbp & 3) << 3);
		BitstreamPutBits(bs, mcbpc_inter_tab[mcbpc].code,
						 mcbpc_inter_tab[mcbpc].len);
	}

	/* ac prediction flag */
	if (pMB->acpred_directions[0])
		BitstreamPutBits(bs, 1, 1);
	else
		BitstreamPutBits(bs, 0, 1);

	/* write cbpy */
	BitstreamPutBits(bs, xvid_cbpy_tab[cbpy].code, xvid_cbpy_tab[cbpy].len);