bitstream.c

一个简单的RTSP客户端实现源码

					BitstreamSkip(bs, 1);					// sadct_disable
				}

				if (BitstreamGetBit(bs))						// not_8_bit
				{
					//DEBUG("+ not_8_bit [IGNORED/TODO]");
					quant_bits = BitstreamGetBits(bs, 4);	// quant_precision
					BitstreamSkip(bs, 4);						// bits_per_pixel
				}
				else
				{
					quant_bits = 5;
				}

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

				quant_type = BitstreamGetBit(bs);		// quant_type
				// DEBUG1("**** quant_type", dec->quant_type);

				if (quant_type)
				{
					if (BitstreamGetBit(bs))		// load_intra_quant_mat
					{
					}
					else
						//set_intra_matrix(get_default_intra_matrix());

					if (BitstreamGetBit(bs))		// load_inter_quant_mat
					{
					}
					else
						//set_inter_matrix(get_default_inter_matrix());

					if (shape == VIDOBJLAY_SHAPE_GRAYSCALE)
					{
						// TODO
						fprintf(stderr,"TODO: grayscale matrix stuff\n");
						return -1;
					}

				}

			
				if (vol_ver_id != 1)
				{
					quarterpel = BitstreamGetBit(bs);	// quarter_sampe
					if (quarterpel)
					{
						fprintf(stderr,"IGNORED/TODO: quarter_sample\n");
					}
				}
				else
				{
					quarterpel = 0;
				}

				if (!BitstreamGetBit(bs))			// complexity_estimation_disable
				{
					fprintf(stderr,"TODO: complexity_estimation header\n");
					// TODO
					return -1;
				}

				if (!BitstreamGetBit(bs))			// resync_marker_disable
				{
					fprintf(stderr,"IGNORED/TODO: !resync_marker_disable\n");
					// TODO
				}

				if (BitstreamGetBit(bs))		// data_partitioned
				{
					fprintf(stderr,"+ data_partitioned\n");
					BitstreamSkip(bs, 1);		// reversible_vlc
				}

				if (vol_ver_id != 1)
				{
					if (BitstreamGetBit(bs))			// newpred_enable
					{
						fprintf(stderr,"+ newpred_enable\n");
						BitstreamSkip(bs, 2);			// requested_upstream_message_type
						BitstreamSkip(bs, 1);			// newpred_segment_type
					}
					if (BitstreamGetBit(bs))			// reduced_resolution_vop_enable
					{
						fprintf(stderr,"TODO: reduced_resolution_vop_enable\n");
						// TODO
						return -1;
					}
				}
				
				if (BitstreamGetBit(bs))	// scalability
				{
					// TODO
					fprintf(stderr,"TODO: scalability\n");
					return -1;
				}
			}
			else	// dec->shape == BINARY_ONLY
			{
				if (vol_ver_id != 1)
				{
					if (BitstreamGetBit(bs))	// scalability
					{
						// TODO
						fprintf(stderr,"TODO: scalability\n");
						return -1;
					}
				}
				BitstreamSkip(bs, 1);			// resync_marker_disable

			}
			param->width = width;
		  param->height = height;
			param->time_inc_bits  = time_inc_bits;
			param->framerate = (time_inc_resolution+1)*1000/1001;
			return 1;
		}
		else if (start_code == GRPOFVOP_START_CODE)
		{
			// DEBUG("group_of_vop");
			BitstreamSkip(bs, 32);
			{
				
				hours = BitstreamGetBits(bs, 5);
				minutes = BitstreamGetBits(bs, 6);
				READ_MARKER();
				seconds = BitstreamGetBits(bs, 6);
				// DEBUG3("hms", hours, minutes, seconds);
			}
			BitstreamSkip(bs, 1);			// closed_gov
			BitstreamSkip(bs, 1);			// broken_link
		}
		else if (start_code == VOP_START_CODE)
		{
		  if (findvol != 0) return -1;
			// DEBUG("vop_start_code");
			BitstreamSkip(bs, 32);						// vop_start_code

			coding_type = BitstreamGetBits(bs, 2);		// vop_coding_type
			//DEBUG1("coding_type", coding_type);

			while (BitstreamGetBit(bs) != 0) ;			// time_base
	
			READ_MARKER();
	 
			//DEBUG1("time_inc_bits", dec->time_inc_bits);
			//DEBUG1("vop_time_incr", BitstreamShowBits(bs, dec->time_inc_bits));
			if (time_inc_bits)
			{
				BitstreamSkip(bs, time_inc_bits);	// vop_time_increment
			}

			READ_MARKER();

			if (!BitstreamGetBit(bs))					// vop_coded
			{
				return N_VOP;
			}

		
			if (coding_type != I_VOP)
			{
				rounding = BitstreamGetBit(bs);	// rounding_type
				//DEBUG1("rounding", *rounding);
			}

			if (shape != VIDOBJLAY_SHAPE_RECTANGULAR)
			{
							
				temp_width = BitstreamGetBits(bs, 13);
				READ_MARKER();
				temp_height = BitstreamGetBits(bs, 13);
				READ_MARKER();
				horiz_mc_ref = BitstreamGetBits(bs, 13);
				READ_MARKER();
				vert_mc_ref = BitstreamGetBits(bs, 13);
				READ_MARKER();

				// DEBUG2("vop_width/height", width, height);
				// DEBUG2("ref             ", horiz_mc_ref, vert_mc_ref);

				BitstreamSkip(bs, 1);				// change_conv_ratio_disable
				if (BitstreamGetBit(bs))			// vop_constant_alpha
				{
					BitstreamSkip(bs, 8);			// vop_constant_alpha_value
				}
			}
				

			if (shape != VIDOBJLAY_SHAPE_BINARY_ONLY)
			{
				// intra_dc_vlc_threshold
				intra_dc_threshold = intra_dc_threshold_table[ BitstreamGetBits(bs,3) ];

				if (interlacing)
				{
					if ((top_field_first = BitstreamGetBit(bs)))
					{
						fprintf(stderr,"vop: top_field_first\n");
					}
					if ((alternate_vertical_scan = BitstreamGetBit(bs)))
					{
						fprintf(stderr,"vop: alternate_vertical_scan");
					}
				}
			}
						
			quant = BitstreamGetBits(bs, quant_bits);		// vop_quant
			//DEBUG1("quant", *quant);
						
			if (coding_type != I_VOP)
			{
				fcode = BitstreamGetBits(bs, 3);			// fcode_forward
			}
				
			if (coding_type == B_VOP)
			{
				// *fcode_backward = BitstreamGetBits(bs, 3);		// fcode_backward
			}
			return coding_type;
		}
		else if (start_code == USERDATA_START_CODE)
		{
			// DEBUG("user_data");
			BitstreamSkip(bs, 32);		// user_data_start_code
		}
		else if ((start_code & 0xfffffc03) == 0x00008002) 
		{
		  // Short video header.  Skip short_video_start_marker,
		  // temporal reference, marker and zero bit
		  have_short_header = 1;
		  shape = VIDOBJLAY_SHAPE_RECTANGULAR;
		  interlacing = 0;
		  quant_bits = 5;
		  quant_type = 0;
		  quarterpel = 0;
		  intra_dc_threshold = intra_dc_threshold_table[0];
		  rounding = 0;
		  fcode = 1;
		  BitstreamSkip(bs, 22);
		  BitstreamSkip(bs, 8 + 5);
		  source_format = BitstreamGetBits(bs, 3);
		  switch (source_format) {
		  case 1: // sub-QCIF
		    width = 128;
		    height = 96;
		    break;
		  case 2: // QCIF
		    width = 176;
		    height = 144;
		    break;
		  case 3: // CIF
		    width = 352;
		    height = 288;
		    break;
		  case 4: // 4CIF
		    width = 704;
		    height = 576;
		    break;
		  case 5:
		    width = 1408;
		    height = 1152;
		    break;
		  default:
		    fprintf(stderr,"FATAL: illegal code in short video header %u\n", source_format);
		    return -1;
		  }
		  if (findvol == 0) {
		    if (temp_width != width || temp_height != height)
		      {
						fprintf(stderr,"FATAL: video dimension discrepancy ***");
						fprintf(stderr,"bitstream width %u /height %u \n", width, height);
						fprintf(stderr,"param width %u /height %u \n", width, height);
						return -1;
		      }
		  } 
			else 
			{
		    width = temp_width;
		    height = temp_height;
				param->width = width;
				param->height = height;
		    return 1;
		  }
		  if (BitstreamGetBit(bs)) 
			{
		    // P frame
		    coding_type = P_VOP;
		  }
			else 
			{
		    coding_type = I_VOP;
		  }
		  BitstreamSkip(bs, 4); // skip 4 reserved 0 bits
		  quant = BitstreamGetBits(bs, 5);
		  BitstreamSkip(bs, 1);
		  while (BitstreamGetBit(bs) == 1) BitstreamSkip(bs, 8); // pei and psupp
		  return coding_type;
		}
		else  // start_code == ?
		{
			if (BitstreamShowBits(bs, 24) == 0x000001)
			{
				fprintf(stderr,"*** WARNING: unknown start_code%u\n", BitstreamShowBits(bs, 32));
			}
			BitstreamSkip(bs, 8);
		}
	}
	while ((BitstreamPos(bs) >> 3) < bs->length);

	fprintf(stderr,"*** WARNING: no vop_start_code found");
	if (findvol != 0) return 0;
	return -1; /* ignore it */
}


////////////////////////////////////
/* initialise bitstream structure */

void BitstreamInit(Bitstream * bs,/*const uint32_t * bitstream,*/uint32_t length)
{
	uint32_t tmp;
	bs->start = bs->tail = (uint32_t*)bitstream;
	
	tmp = *(uint32_t *)bitstream;
	bs->bufa = tmp;
	tmp = *((uint32_t *)bitstream+1);

	bs->bufb = tmp;

	bs->buf = 0;
	bs->pos = 0;
	bs->length = length;

}


//////////////////////////////
// entire function added for mpeg4ip

int decoder_find_vol( uint32_t length,XVID_DEC_PARAM * param)
{
	Bitstream bs;
	int ret;
	BitstreamInit(&bs,length);

	ret = BitstreamReadHeaders(&bs,param,1);
	return ret;
}



int parse_vovod(unsigned char *ConfigHex,unsigned int HexLen,unsigned *FrameRate,unsigned *TimeIncBits,unsigned *Width,unsigned *Height)
{
  int ret = -1;
  int size_int = 0;
  int i = 0,j = 0;
  XVID_DEC_PARAM param;
  // Get the VO/VOL header.  If we fail, set the bytestream back
	size_int = HexLen/sizeof(uint32_t)+1;
	bitstream = (uint32_t *)malloc(size_int*sizeof(uint32_t));
	if(bitstream == NULL)
	{
		fprintf(stderr,"bitstream alloc failed \n");
		return ret;	
	}
	for(i=0;i<size_int;i++)
	{
		bitstream[i] = ((ConfigHex[j]&0xff)<<24)|((ConfigHex[j+1]&0xff)<<16)|((ConfigHex[j+2]&0xff)<<8)|(ConfigHex[j+3]&0xff);
		j = j+sizeof(uint32_t);
		fprintf(stderr,"bitstream i %d,%x\n",i,*(bitstream+i));
	}
	ret = 0;
	ret = decoder_find_vol(HexLen, &param);
	*Width = param.width;
	*Height = param.height;
	*TimeIncBits = param.time_inc_bits;
	*FrameRate = param.framerate;
	free(bitstream);
	return ret;
}