bitstream.c

mpeg4代码,比较具体

/*****************************************************************************
 *
 *  XVID MPEG-4 VIDEO CODEC
 *  - Bitstream reader/writer functions -
 *
 *  Copyright (C) 2001-2002 - Peter Ross <[e-mail]>
 *
 *  This file is part of XviD, a free MPEG-4 video encoder/decoder
 *
 *  XviD 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
 *
 *  Under section 8 of the GNU General Public License, the copyright
 *  holders of XVID explicitly forbid distribution in the following
 *  countries:
 *
 *    - Japan
 *    - United States of America
 *
 *  Linking XviD statically or dynamically with other modules is making a
 *  combined work based on XviD.  Thus, the terms and conditions of the
 *  GNU General Public License cover the whole combination.
 *
 *  As a special exception, the copyright holders of XviD give you
 *  permission to link XviD with independent modules that communicate with
 *  XviD solely through the VFW1.1 and DShow interfaces, regardless of the
 *  license terms of these independent modules, and to copy and distribute
 *  the resulting combined work under terms of your choice, provided that
 *  every copy of the combined work is accompanied by a complete copy of
 *  the source code of XviD (the version of XviD used to produce the
 *  combined work), being distributed under the terms of the GNU General
 *  Public License plus this exception.  An independent module is a module
 *  which is not derived from or based on XviD.
 *
 *  Note that people who make modified versions of XviD are not obligated
 *  to grant this special exception for their modified versions; it is
 *  their choice whether to do so.  The GNU General Public License gives
 *  permission to release a modified version without this exception; this
 *  exception also makes it possible to release a modified version which
 *  carries forward this exception.
 *
 * $Id: bitstream.c,v 1.37.2.1 2003/07/28 12:39:27 edgomez Exp $
 *
 ****************************************************************************/

#include "bitstream.h"
#include "zigzag.h"
#include "../quant/quant_matrix.h"

/*****************************************************************************
 * Functions
 ****************************************************************************/

static uint32_t __inline
log2bin(uint32_t value)
{
/* Changed by Chenm001 */
#if !defined(_MSC_VER)
	int n = 0;

	while (value) {
		value >>= 1;
		n++;
	}
	return n;
#else
	__asm {
		bsr eax, value 
		inc eax
	}
#endif
}


static const uint32_t intra_dc_threshold_table[] = {
	32,							/* never use */
	13,
	15,
	17,
	19,
	21,
	23,
	1,
};


void
bs_get_matrix(Bitstream * bs,
			  uint8_t * matrix)
{
	int i = 0;
	int last, value = 0;

	do {
		last = value;
		value = BitstreamGetBits(bs, 8);
		matrix[scan_tables[0][i++]] = value;
	}
	while (value != 0 && i < 64);
        i--;    /* fix little bug at coeff not full */

	while (i < 64) {
		matrix[scan_tables[0][i++]] = last;
	}
}



/* for PVOP addbits == fcode - 1 */
/* for BVOP addbits == max(fcode,bcode) - 1 */
/* returns mbpos */
int
read_video_packet_header(Bitstream *bs, const int addbits, int * quant)
{
	int nbits;
	int mbnum;
	int hec;
	
	nbits = NUMBITS_VP_RESYNC_MARKER + addbits;

	BitstreamSkip(bs, BitstreamNumBitsToByteAlign(bs));
	BitstreamSkip(bs, nbits);

	DPRINTF(DPRINTF_STARTCODE, "<video_packet_header>");

	/* if (dec->shape != VIDOBJLAY_SHAPE_RECTANGULAR) { */
		/* hec */
		/* vop_width */
		/* marker_bit */
		/* vop_height */
		/* marker_bit */

	/*} */

	mbnum = BitstreamGetBits(bs, 9);
	DPRINTF(DPRINTF_HEADER, "mbnum %i", mbnum);

	/* if (dec->shape != VIDOBJLAY_SHAPE_BINARYONLY) */
	*quant = BitstreamGetBits(bs, 5);
	DPRINTF(DPRINTF_HEADER, "quant %i", *quant);

	/* if (dec->shape != VIDOBJLAY_SHAPE_RECTANGULAR) */
	hec = BitstreamGetBit(bs);
	DPRINTF(DPRINTF_HEADER, "header_extension_code %i", hec);
	/* if (hec) */
	/*   .. decoder hec-header ... */

	return mbnum;
}



/*
decode headers
returns coding_type, or -1 if error
*/

#define VIDOBJ_START_CODE_MASK		0x0000001f
#define VIDOBJLAY_START_CODE_MASK	0x0000000f

int
BitstreamReadHeaders(Bitstream * bs,
					 DECODER * dec,
					 uint32_t * rounding,
					 uint32_t * quant,
					 uint32_t * fcode_forward,
					 uint32_t * fcode_backward,
					 uint32_t * intra_dc_threshold)
{
	uint32_t vol_ver_id;
	static uint32_t time_increment_resolution;
	uint32_t coding_type;
	uint32_t start_code;
	uint32_t time_incr = 0;
	int32_t time_increment = 0;

	do {
		BitstreamByteAlign(bs);
		start_code = BitstreamShowBits(bs, 32);

		if (start_code == VISOBJSEQ_START_CODE) {

			int profile;

			DPRINTF(DPRINTF_STARTCODE, "<visual_object_sequence>");

			BitstreamSkip(bs, 32);	/* visual_object_sequence_start_code */
			profile = BitstreamGetBits(bs, 8);	/* profile_and_level_indication */

			DPRINTF(DPRINTF_HEADER, "profile_and_level_indication %i", profile);

		} else if (start_code == VISOBJSEQ_STOP_CODE) {

			BitstreamSkip(bs, 32);	/* visual_object_sequence_stop_code */

			DPRINTF(DPRINTF_STARTCODE, "</visual_object_sequence>");

		} else if (start_code == VISOBJ_START_CODE) {

			DPRINTF(DPRINTF_STARTCODE, "<visual_object>");

			BitstreamSkip(bs, 32);	/* visual_object_start_code */
			if (BitstreamGetBit(bs))	/* is_visual_object_identified */
			{
				vol_ver_id = BitstreamGetBits(bs, 4);	/* visual_object_ver_id */
				DPRINTF(DPRINTF_HEADER,"ver_id %i", vol_ver_id);
				BitstreamSkip(bs, 3);	/* visual_object_priority */
			} else {
				vol_ver_id = 1;
			}

			if (BitstreamShowBits(bs, 4) != VISOBJ_TYPE_VIDEO)	/* visual_object_type */
			{
				DPRINTF(DPRINTF_ERROR, "visual_object_type != video");
				return -1;
			}
			BitstreamSkip(bs, 4);

			/* video_signal_type */

			if (BitstreamGetBit(bs))	/* video_signal_type */
			{
				DPRINTF(DPRINTF_HEADER,"+ video_signal_type");
				BitstreamSkip(bs, 3);	/* video_format */
				BitstreamSkip(bs, 1);	/* video_range */
				if (BitstreamGetBit(bs))	/* color_description */
				{
					DPRINTF(DPRINTF_HEADER,"+ color_description");
					BitstreamSkip(bs, 8);	/* color_primaries */
					BitstreamSkip(bs, 8);	/* transfer_characteristics */
					BitstreamSkip(bs, 8);	/* matrix_coefficients */
				}
			}
		} else if ((start_code & ~VIDOBJ_START_CODE_MASK) == VIDOBJ_START_CODE) {

			DPRINTF(DPRINTF_STARTCODE, "<video_object>");
			DPRINTF(DPRINTF_HEADER, "vo id %i", start_code & VIDOBJ_START_CODE_MASK);

			BitstreamSkip(bs, 32);	/* video_object_start_code */

		} else if ((start_code & ~VIDOBJLAY_START_CODE_MASK) == VIDOBJLAY_START_CODE) {

			DPRINTF(DPRINTF_STARTCODE, "<video_object_layer>");
			DPRINTF(DPRINTF_HEADER, "vol id %i", start_code & VIDOBJLAY_START_CODE_MASK);

			BitstreamSkip(bs, 32);	/* video_object_layer_start_code */

			BitstreamSkip(bs, 1);	/* random_accessible_vol */

			/* video_object_type_indication */
			if (BitstreamShowBits(bs, 8) != VIDOBJLAY_TYPE_SIMPLE && BitstreamShowBits(bs, 8) != VIDOBJLAY_TYPE_CORE && BitstreamShowBits(bs, 8) != VIDOBJLAY_TYPE_MAIN && BitstreamShowBits(bs, 8) != 0)	/* BUGGY DIVX */
			{
				DPRINTF(DPRINTF_ERROR,"video_object_type_indication %i not supported ",
					BitstreamShowBits(bs, 8));
				return -1;
			}
			BitstreamSkip(bs, 8);


			if (BitstreamGetBit(bs))	/* is_object_layer_identifier */
			{
				DPRINTF(DPRINTF_HEADER, "+ is_object_layer_identifier");
				vol_ver_id = BitstreamGetBits(bs, 4);	/* video_object_layer_verid */
				DPRINTF(DPRINTF_HEADER,"ver_id %i", vol_ver_id);
				BitstreamSkip(bs, 3);	/* video_object_layer_priority */
			} else {
				vol_ver_id = 1;
			}

			if (BitstreamGetBits(bs, 4) == VIDOBJLAY_AR_EXTPAR)	/* aspect_ratio_info */
			{
				DPRINTF(DPRINTF_HEADER, "+ aspect_ratio_info");
				BitstreamSkip(bs, 8);	/* par_width */
				BitstreamSkip(bs, 8);	/* par_height */
			}

			if (BitstreamGetBit(bs))	/* vol_control_parameters */
			{
				DPRINTF(DPRINTF_HEADER, "+ vol_control_parameters");
				BitstreamSkip(bs, 2);	/* chroma_format */
				dec->low_delay = (uint8_t)BitstreamGetBit(bs);	/* low_delay */
				DPRINTF(DPRINTF_HEADER, "low_delay %i", dec->low_delay);
				if (BitstreamGetBit(bs))	/* vbv_parameters */
				{
					DPRINTF(DPRINTF_HEADER,"+ vbv_parameters");
					BitstreamSkip(bs, 15);	/* first_half_bitrate */
					READ_MARKER();
					BitstreamSkip(bs, 15);	/* latter_half_bitrate */
					READ_MARKER();
					BitstreamSkip(bs, 15);	/* first_half_vbv_buffer_size */
					READ_MARKER();
					BitstreamSkip(bs, 3);	/* latter_half_vbv_buffer_size */
					BitstreamSkip(bs, 11);	/* first_half_vbv_occupancy */
					READ_MARKER();
					BitstreamSkip(bs, 15);	/* latter_half_vbv_occupancy */
					READ_MARKER();

				}
			}

			dec->shape = BitstreamGetBits(bs, 2);	/* video_object_layer_shape */
			DPRINTF(DPRINTF_HEADER, "shape %i", dec->shape);

			if (dec->shape == VIDOBJLAY_SHAPE_GRAYSCALE && vol_ver_id != 1) {
				BitstreamSkip(bs, 4);	/* video_object_layer_shape_extension */
			}

			READ_MARKER();

/* *************************** for decode B-frame time *********************** */
			time_increment_resolution = BitstreamGetBits(bs, 16);	/* vop_time_increment_resolution */

			DPRINTF(DPRINTF_HEADER,"vop_time_increment_resolution %i", time_increment_resolution);

/*			time_increment_resolution--; */

			if (time_increment_resolution > 0) {
				dec->time_inc_bits = log2bin(time_increment_resolution-1);
			} else {
				/* dec->time_inc_bits = 0; */
				/* for "old" xvid compatibility, set time_inc_bits = 1 */
				dec->time_inc_bits = 1;
			}

			READ_MARKER();

			if (BitstreamGetBit(bs))	/* fixed_vop_rate */
			{
				DPRINTF(DPRINTF_HEADER, "+ fixed_vop_rate");
				BitstreamSkip(bs, dec->time_inc_bits);	/* fixed_vop_time_increment */
			}

			if (dec->shape != VIDOBJLAY_SHAPE_BINARY_ONLY) {

				if (dec->shape == VIDOBJLAY_SHAPE_RECTANGULAR) {
					uint32_t width, height;

					READ_MARKER();
					width = BitstreamGetBits(bs, 13);	/* video_object_layer_width */
					READ_MARKER();
					height = BitstreamGetBits(bs, 13);	/* video_object_layer_height */
					READ_MARKER();

					DPRINTF(DPRINTF_HEADER, "width %i", width);
					DPRINTF(DPRINTF_HEADER, "height %i", height);

					/* for auto set width & height */
					if (dec->width == 0)
						dec->width = width;
					if (dec->height == 0)
						dec->height = height;

					if (width != dec->width || height != dec->height) {
						DPRINTF(DPRINTF_ERROR, "XVID_DEC_PARAM width/height does not match bitstream");
						return -1;
					}

				}

				dec->interlacing = BitstreamGetBit(bs);
				DPRINTF(DPRINTF_HEADER, "interlace", dec->interlacing);

				if (!BitstreamGetBit(bs))	/* obmc_disable */
				{
					DPRINTF(DPRINTF_ERROR, "obmc_disabled==false not supported");
					/* TODO */
					/* fucking divx4.02 has this enabled */
				}

				if (BitstreamGetBits(bs, (vol_ver_id == 1 ? 1 : 2)))	/* sprite_enable */
				{
					DPRINTF(DPRINTF_ERROR, "spriate_enabled not supported");
					return -1;
				}

				if (vol_ver_id != 1 &&
					dec->shape != VIDOBJLAY_SHAPE_RECTANGULAR) {
					BitstreamSkip(bs, 1);	/* sadct_disable */
				}

				if (BitstreamGetBit(bs))	/* not_8_bit */
				{
					DPRINTF(DPRINTF_HEADER, "not_8_bit==true (ignored)");
					dec->quant_bits = BitstreamGetBits(bs, 4);	/* quant_precision */
					BitstreamSkip(bs, 4);	/* bits_per_pixel */
				} else {
					dec->quant_bits = 5;
				}

				if (dec->shape == VIDOBJLAY_SHAPE_GRAYSCALE) {
					BitstreamSkip(bs, 1);	/* no_gray_quant_update */
					BitstreamSkip(bs, 1);	/* composition_method */
					BitstreamSkip(bs, 1);	/* linear_composition */
				}

				dec->quant_type = BitstreamGetBit(bs);	/* quant_type */
				DPRINTF(DPRINTF_HEADER, "quant_type %i", dec->quant_type);

				if (dec->quant_type) {
					if (BitstreamGetBit(bs))	/* load_intra_quant_mat */
					{
						uint8_t matrix[64];

						DPRINTF(DPRINTF_HEADER, "load_intra_quant_mat");