bitstream.c

MPEG-4编解码的实现(包括MPEG4视音频编解码)

 /******************************************************************************
  *                                                                            *
  *  This file is part of XviD, a free MPEG-4 video encoder/decoder            *
  *                                                                            *
  *  XviD is an implementation of a part of one or more MPEG-4 Video tools     *
  *  as specified in ISO/IEC 14496-2 standard.  Those intending to use this    *
  *  software module in hardware or software products are advised that its     *
  *  use may infringe existing patents or copyrights, and any such use         *
  *  would be at such party's own risk.  The original developer of this        *
  *  software module and his/her company, and subsequent editors and their     *
  *  companies, will have no liability for use of this software or             *
  *  modifications or derivatives thereof.                                     *
  *                                                                            *
  *  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.                                       *
  *                                                                            *
  *  XviD 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  *
  *                                                                            *
  ******************************************************************************/

 /******************************************************************************
  *                                                                            *
  *  bitstream.c                                                               *
  *                                                                            *
  *  Copyright (C) 2001 - Peter Ross <[e-mail]>                    *
  *                                                                            *
  *  For more information visit the XviD homepage: http://www.xvid.org         *
  *                                                                            *
  ******************************************************************************/

 /******************************************************************************
  *																			   *	
  *  Revision history:                                                         *
  *                                                                            *
  *  26.03.2002 interlacing support
  *  03.03.2002 qmatrix writing												   *
  *  03.03.2002 merged BITREADER and BITWRITER								   *
  *	 30.02.2002	intra_dc_threshold support									   *
  *	 04.12.2001	support for additional headers								   *
  *	 16.12.2001	inital version                                           	   *
  *																			   *
  ******************************************************************************/


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

static int __inline log2bin(int value)
{
	int n = 0;
	while (value)
	{
		value >>= 1;
		n++;
	}
	return n;
}


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

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

int BitstreamReadHeaders(Bitstream * bs, DECODER * dec, uint32_t * rounding, 
			 uint32_t * quant, uint32_t * fcode, uint32_t * intra_dc_threshold,
			 int findvol)
{
	uint32_t vol_ver_id;
	uint32_t time_inc_resolution;
	uint32_t coding_type;
	uint32_t start_code;
	
	do
	{
		BitstreamByteAlign(bs);
		start_code = BitstreamShowBits(bs, 32);

		if (start_code == VISOBJSEQ_START_CODE)
		{
			// DEBUG("visual_object_sequence");
			BitstreamSkip(bs, 32);				// visual_object_sequence_start_code
			BitstreamSkip(bs, 8);					// profile_and_level_indication
		}
		else if (start_code == VISOBJSEQ_STOP_CODE)
		{
			BitstreamSkip(bs, 32);				// visual_object_sequence_stop_code
		}
		else if (start_code == VISOBJ_START_CODE)
		{
			// DEBUG("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
				BitstreamSkip(bs, 3);				// visual_object_priority
			}
			else
			{
				vol_ver_id = 1;
			}

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

			// video_signal_type

			if (BitstreamGetBit(bs))				// video_signal_type
			{
				DEBUG("+ video_signal_type");
				BitstreamSkip(bs, 3);				// video_format
				BitstreamSkip(bs, 1);				// video_range
				if (BitstreamGetBit(bs))			// color_description
				{
					DEBUG("+ color_description");
					BitstreamSkip(bs, 8);			// color_primaries
					BitstreamSkip(bs, 8);			// transfer_characteristics
					BitstreamSkip(bs, 8);			// matrix_coefficients
				}
			}
		}
		else if ((start_code & ~0x1f) == VIDOBJ_START_CODE)
		{
			BitstreamSkip(bs, 32);		// video_object_start_code
		} 
		else if ((start_code & ~0xf) == VIDOBJLAY_START_CODE)
		{
			// DEBUG("video_object_layer");
			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
			{
				DEBUG1("video_object_type_indication not supported", BitstreamShowBits(bs, 8));
				return -1;
			}
			BitstreamSkip(bs, 8);


			if (BitstreamGetBit(bs))					// is_object_layer_identifier
			{
				DEBUG("+ is_object_layer_identifier");
				vol_ver_id = BitstreamGetBits(bs,4);		// video_object_layer_verid
				BitstreamSkip(bs, 3);					// video_object_layer_priority
			}
			else
			{
				vol_ver_id = 1;
			}
			//DEBUGI("vol_ver_id", vol_ver_id);

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

			if (BitstreamGetBit(bs))		// vol_control_parameters
			{
				DEBUG("+ vol_control_parameters");
				BitstreamSkip(bs, 2);						// chroma_format
				BitstreamSkip(bs, 1);						// low_delay
				if (BitstreamGetBit(bs))					// vbv_parameters
				{
					DEBUG("+ 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
			// DEBUG1("shape", dec->shape);
			
			if (dec->shape == VIDOBJLAY_SHAPE_GRAYSCALE && vol_ver_id != 1)
			{
				BitstreamSkip(bs, 4);		// video_object_layer_shape_extension
			}

			READ_MARKER();

			time_inc_resolution = BitstreamGetBits(bs, 16);	// vop_time_increment_resolution
			time_inc_resolution--;
			if (time_inc_resolution > 0)
			{
				dec->time_inc_bits = log2bin(time_inc_resolution);
			}
			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
			{
				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
					//DEBUGI("width", width);
					READ_MARKER();
					height = BitstreamGetBits(bs, 13);		// video_object_layer_height
					//DEBUGI("height", height);	
					READ_MARKER();

					if (findvol == 0) {
					  if (width != dec->width || height != dec->height)
					    {
					      DEBUG("FATAL: video dimension discrepancy ***");
					      DEBUG2("bitstream width/height", width, height);
					      DEBUG2("param width/height", dec->width, dec->height);
					      return -1;
					    }
					} else {
					  dec->width = width;
					  dec->height = height;
					}

				}

				if ((dec->interlacing = BitstreamGetBit(bs)))
				{
					DEBUG("vol: interlacing");
				}

				if (!BitstreamGetBit(bs))				// obmc_disable
				{
					DEBUG("IGNORED/TODO: !obmc_disable");
					// TODO
					// fucking divx4.02 has this enabled
				}

				if (BitstreamGetBits(bs, (vol_ver_id == 1 ? 1 : 2)))  // sprite_enable
				{
					DEBUG("sprite_enable; 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
				{
					DEBUG("+ not_8_bit [IGNORED/TODO]");
					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
				// DEBUG1("**** quant_type", dec->quant_type);

				if (dec->quant_type)
				{
					if (BitstreamGetBit(bs))		// load_intra_quant_mat
					{
						uint8_t matrix[64];
						bs_get_matrix(bs, matrix);
						set_intra_matrix(matrix);
					}
					else
						set_intra_matrix(get_default_intra_matrix());

					if (BitstreamGetBit(bs))		// load_inter_quant_mat
					{
						uint8_t matrix[64]; 
						bs_get_matrix(bs, matrix);
						set_inter_matrix(matrix);
					}
					else
						set_inter_matrix(get_default_inter_matrix());

					if (dec->shape == VIDOBJLAY_SHAPE_GRAYSCALE)
					{
						// TODO
						DEBUG("TODO: grayscale matrix stuff");
						return -1;
					}

				}

			
				if (vol_ver_id != 1)
				{
					dec->quarterpel = BitstreamGetBit(bs);	// quarter_sampe
					if (dec->quarterpel)
					{
						DEBUG("IGNORED/TODO: quarter_sample");
					}
				}
				else
				{
					dec->quarterpel = 0;
				}

				if (!BitstreamGetBit(bs))			// complexity_estimation_disable
				{
					DEBUG("TODO: complexity_estimation header");
					// TODO
					return -1;