annexb.c

davinci avs.......................................................

/*!
 *************************************************************************************
 * \file 
 *    bitstream.c
 * \brief
 *    bitstream handling including high-level syntax parset and NAL de-compression etc.
 * \notes:
 *    upadated @ June 14th 2005 according to the FCD 
 *************************************************************************************
 */

#include <stdlib.h>
//#include <memory.h>
#include "global.h"
#include "annexb.h"
#include "memalloc.h"
#include "nalu.h"


FILE *bits = NULL;                //!< the bit stream file
InputStream IRABS , *pIRABS = &IRABS;

 /*! 
 *************************************************************************************
 * \brief : 
 *    Open the Byte Stream
 *************************************************************************************
 */
void OpenAnnexbFile(char *fn)
{
  if ( NULL == (bits=fopen(fn, "rb")) )    //!< open bitstream file in bit format
  {
	  snprintf (errortext, ET_SIZE, "Cannot open Annex B ByteStream file '%s'", input->infile);
	  error(errortext,500);
  }

}

 /*! 
 *************************************************************************************
 * \brief : 
 *    Close the Byte Stream
 *************************************************************************************
 */
void CloseAnnexbFile()
{
  fclose(bits);
}


 /*! 
 *************************************************************************************
 * \brief : 
 *    get the current nalu_header
 * \notes :
 *     code	:	OK
 *		  -1	:	arrive at stream end and start code is not found
 *		  -2	:	Pop->iBytesition error
 *************************************************************************************
 */
int GetNaluHeader(InputStream *p)
{
	int i, m=0;//change m=0 by stephen for debug 
	unsigned char a,b,c;	// a b c 0 1 2 3 4 ... M-3 M-2 M-1
	while(1)
	{
		if(p->iBytePosition >= p->iBufBytesNum - 3)	//if all bytes in buffer has been searched
		{
			m = p->iBufBytesNum - p->iBytePosition;
			if(m <0)
				return -2;	// p->iBytePosition error
			if(m==1)  c=p->buf[p->iBytePosition];
			if(m==2){ c=p->buf[p->iBytePosition+1]; b=p->buf[p->iBytePosition];}
			if(m==3){ c=p->buf[p->iBytePosition+2]; b=p->buf[p->iBytePosition+1];a=p->buf[p->iBytePosition];}
			p->iBufBytesNum = fread(p->buf,1,SVA_STREAM_BUF_SIZE,bits);
			p->iBytePosition = 0;
		}
		if(p->iBufBytesNum + m < 4)  return -1;  //arrive at stream end and start code is not found
		if(m==1 && c==0 && p->buf[0]==0 && p->buf[1]==1)
		{
			p->iBytePosition	= 3;
			p->iClearBitsNum	= 0;
			p->iStuffBitsNum	= 0;
			p->iBitsCount		+= 32;
			p->uPre3Bytes		= p->buf[2]+256;
			//printf("p->uPre3Bytes is %x  n1\n",p->uPre3Bytes);
			return p->buf[2];
		}
		if(m==2 && b==0 && c==0 && p->buf[0]==1)
		{
			p->iBytePosition	= 2;
			p->iClearBitsNum	= 0;
			p->iStuffBitsNum	= 0;
			p->iBitsCount		+= 32;
			p->uPre3Bytes		= p->buf[1]+256;
			//printf("p->uPre3Bytes is %x  n2\n",p->uPre3Bytes);
			return p->buf[1];
		}
		if(m==3 && a==0 && b==0 && c==1)
		{
			p->iBytePosition	= 1;
			p->iClearBitsNum	= 0;
			p->iStuffBitsNum	= 0;
			p->iBitsCount		+= 32;
			p->uPre3Bytes		= p->buf[0]+256;
			//printf("p->uPre3Bytes is %x  n3\n",p->uPre3Bytes);
			return p->buf[0];
		}
		for(i = p->iBytePosition; i < p->iBufBytesNum - 3; i++)
		{
			if(p->buf[i]==0 && p->buf[i+1]==0 && p->buf[i+2]==1)
			{
				p->iBytePosition	= i+4;
				p->iClearBitsNum	= 0;
				p->iStuffBitsNum	= 0;
				p->iBitsCount		+= 24;
				p->uPre3Bytes		= p->buf[i+3]+256;
				//printf("p->uPre3Bytes is %x  n0\n",p->uPre3Bytes);
				return p->buf[i+3];
			}
			p->iBitsCount += 8;
		}
		p->iBytePosition = i;
	}
}
 /*! 
 *************************************************************************************
 * \brief : 
 *    read one byte of the nalu payload
 * \notes :
 *      code	:	meet the nalu header
 *		  -1	:	arrive at stream end
 *		  -2	:	OK
 *************************************************************************************
 */
int read_1_byte(InputStream *p, int *value)
{
	int i,k,j;
	unsigned char temp[4];
	int read_len=0;//WJP FOR NAL ADD

	i = p->iBytePosition;
	k = p->iBufBytesNum - i;
	if(k < 4)
	{
		for(j=0;j<k;j++) 
			temp[j] = p->buf[i+j];
		read_len/*p->iBufBytesNum*/ = fread(p->buf+k,1,SVA_STREAM_BUF_SIZE-k,bits);//WJP FOR NAL ADD
		if(read_len == 0)//WJP FOR NAL ADD
		{
			if(k>0)
			{
				p->uClearBits = (p->uClearBits << 8) | p->buf[i];
				p->iClearBitsNum += 8;
				p->iBytePosition++;
				*value = p->buf[i];
				return -2;
			}
			else
			{
				return -1;//arrive at stream end
			}
		}
		else
		{
			for(j=0;j<k;j++) 
				p->buf[j] = temp[j];
			p->iBufBytesNum = read_len + k;//WJP FOR NAL ADD
			i = p->iBytePosition = 0;
		}
	}
	if(p->buf[i]==0 && p->buf[i+1]==0 && p->buf[i+2]==1)	
	{
		//printf("The next code is %x  c\n",p->buf[i+3]);
		return p->buf[i+3];// meet another start code
	}
	p->uPre3Bytes = ((p->uPre3Bytes<<8) | p->buf[i]) & 0x00ffffff;

	p->uClearBits = (p->uClearBits << 8) | p->buf[i];
	p->iClearBitsNum += 8;
	p->iBytePosition++;
	*value = p->buf[i];
				
	return -2;	
}

 /*! 
 *************************************************************************************
 * \brief : 
 *    get the a unit start with a start code.
 * \notes :
 *      code	:	meet the nalu header
 *		  -1	:	arrive at stream end
 *		  -2	:	OK
 *************************************************************************************
 */
int GetOneUnit (NALU_t *nalu, int *next_nalu_type)
{
	int i,j,k;
	int nalu_over=0;

	i = GetNaluHeader(pIRABS);
	nalu->buf[0] = i;
	nalu->nal_unit_type = i & 31;
	i >>= 5;
	nalu->nal_reference_idc = i & 3;
	i >>= 2;
	nalu->forbidden_bit = i & 1;

#if ERR_REPORT
  CheckNALUValid(nalu->buf[0],p_err);
#endif

	//GET the nalu payload and find the next nalu type
	k=1;
	while(!nalu_over)
	{
		i = read_1_byte(pIRABS,&j);
		//code	:	meet the nalu header
		//	-1	:	arrive at stream end
		//	-2	:	OK
				
		if(i == -2)
			nalu->buf[k++] = (char)j;
		else if(i == -1)
		{
			*next_nalu_type = -1;
			break;
		}
		else
		{
			nalu_over = 1;
			*next_nalu_type = i & 31;
		}
	}

	nalu->len = k;

  return 1;
}


void DecodeTrailingBits(Bitstream *bitstream)
{

  int ctr_bit, bitoffset, trailingbits;
  
  bitoffset = 0; 
  //find trailing 1
  ctr_bit = (bitstream->streamBuffer[currStream->bitstream_length-1] & (0x01<<bitoffset));   // set up control bit
  
  while (ctr_bit==0)
  {                 // find trailing 1 bit
    bitoffset++;
    //if(bitoffset == 8) 
    //{
    //  if(last_byte_pos == 0)
    //    printf(" Panic: All zero data sequence in RBSP \n");
    //  assert(last_byte_pos != 0);
    //  last_byte_pos -= 1;
    //  bitoffset = 0;
   // }
    ctr_bit= bitstream->streamBuffer[currStream->bitstream_length-1] & (0x01<<(bitoffset));
  }
  
  trailingbits = (0x01 << bitoffset);


#if TRACE
  tracebits2("Byte Stream Trailing Bits",(bitoffset+1),trailingbits);
#endif

}


void DecodeTrailingBits1(Bitstream *bitstream,int bitstream_length)
{

  int ctr_bit, bitoffset, trailingbits;
  
  bitoffset = 0; 
  //find trailing 1
  ctr_bit = (bitstream->streamBuffer[bitstream_length-1] & (0x01<<bitoffset));   // set up control bit
  
  while (ctr_bit==0)
  {                 // find trailing 1 bit
    bitoffset++;
    //if(bitoffset == 8) 
    //{
    //  if(last_byte_pos == 0)
    //    printf(" Panic: All zero data sequence in RBSP \n");
    //  assert(last_byte_pos != 0);
    //  last_byte_pos -= 1;
    //  bitoffset = 0;
   // }
    ctr_bit= bitstream->streamBuffer[bitstream_length-1] & (0x01<<(bitoffset));
  }
  
  trailingbits = (0x01 << bitoffset);


#if TRACE
  tracebits2("Byte Stream Trailing Bits",(bitoffset+1),trailingbits);
#endif

}