www.pudn.com > wm2.5.zip > bitstream.c
/*!
*************************************************************************************
* \file bitstream.c
*
* \brief
*
*
* \date: updating
*
* \author
*
*************************************************************************************
*/
#include
#include
#include
#include "global.h"
#include "bitstream.h"
#include "memalloc.h"
#include "nalu.h"//WJP FOR NAL
////////////////////////////////////////////////////////////////////////////////
FILE *bits = NULL; //!< the bit stream file
//WJP FOR SLICE
//extern int Position_of_Slice_in_Picbuff[176];
//extern int Slice_Enable;
#define SVA_STREAM_BUF_SIZE 1024
//unsigned char bit[8] = {0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01};
typedef struct {
unsigned char buf[SVA_STREAM_BUF_SIZE]; //流缓冲区,size must be large than 3 bytes
unsigned int uClearBits; //不含填充位的位缓冲，32位，初始值是0xFFFFFFFF
unsigned int uPre3Bytes; // 含填充位的位缓冲，32位，初始值是0x00000000
int iBytePosition; //当前字节位置
int iBufBytesNum; //最近一次读入缓冲区的字节数
int iClearBitsNum; //不含填充位的位的个数
int iStuffBitsNum; //已剔除的填充位的个数，遇到开始码时置0
int iBitsCount; //码流总位数
} InputStream;
//InputStream IRABS;
InputStream IRABS , *pIRABS = &IRABS;
/*
*************************************************************************
* Function:get the current nalu_header.
* Input:
* Output:
* Return:
code : OK
-1 : arrive at stream end and start code is not found
-2 : Pop->iBytesition error
* Author: Jianpeng Wang
*************************************************************************
*/
int GetNaluHeader(InputStream *p)
{
int i, m;
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;
}
}
/*
*************************************************************************
* Function:read one byte of the nalu payload
* Input:
* Output:
* Return:
code : meet the nalu header
-1 : arrive at stream end
-2 : OK
* Author: Jianpeng Wang
*************************************************************************
*/
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;jbuf[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;jbuf[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;
}
/*
*************************************************************************
* Function:get the a unit start with a start code.
* Input:
* Output:
* Return:
* Attention: Modified by Jianpeng Wang
*************************************************************************
*/
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;
//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;
}