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/*!
************************************************************************
* \file nalu.c
*
* \brief
* Decoder NALU support functions
*
* \author
* Main contributors (see contributors.h for copyright, address and affiliation details)
* - Stephan Wenger <stewe@cs.tu-berlin.de>
************************************************************************
*/
#include "global.h"
#include "nalu.h"
#include "memalloc.h"
#include "meminput.h"
/*!
*************************************************************************************
* \brief
* Initialize bitstream reading structure
*
* \param
* p_Vid: Imageparameter information
* \param
* filemode:
*
*************************************************************************************
*/
void OpenMemory(VideoParameters *p_Vid, const char *fn);
void CloseMemory(VideoParameters *p_Vid);
int GetMemoryNALU (VideoParameters *p_Vid, NALU_t *nalu);
void initBitsFile (VideoParameters *p_Vid)
{
malloc_mem_input(p_Vid);
p_Vid->nalu = AllocNALU(MAX_CODED_FRAME_SIZE);
}
/*!
*************************************************************************************
* \brief
* Converts a NALU to an RBSP
*
* \param
* nalu: nalu structure to be filled
*
* \return
* length of the RBSP in bytes
*************************************************************************************
*/
static int NALUtoRBSP (NALU_t *nalu)
{
assert (nalu != NULL);
nalu->len = EBSPtoRBSP (nalu->buf, nalu->len) ;
return nalu->len ;
}
/*!
************************************************************************
* \brief
* Read the next NAL unit (with error handling)
************************************************************************
*/
int read_next_nalu(VideoParameters *p_Vid, NALU_t *nalu)
{
InputParameters *p_Inp = p_Vid->p_Inp;
int ret;
ret = GetMemoryNALU(p_Vid, nalu);
if (ret < 0)
{
error ("Error while getting the next NALU, exit\n", 601);
}
if (ret == 0)
{
return 0;
}
//In some cases, zero_byte shall be present. If current NALU is a VCL NALU, we can't tell
//whether it is the first VCL NALU at this point, so only non-VCL NAL unit is checked here.
CheckZeroByteNonVCL(p_Vid, nalu);
ret = NALUtoRBSP(nalu);
if (ret < 0)
error ("Invalid startcode emulation prevention found.", 602);
// Got a NALU
if (nalu->forbidden_bit)
{
error ("Found NALU with forbidden_bit set, bit error?", 603);
}
return nalu->len;
}
void CheckZeroByteNonVCL(VideoParameters *p_Vid, NALU_t *nalu)
{
int CheckZeroByte=0;
//This function deals only with non-VCL NAL units
if(nalu->nal_unit_type>=1&&nalu->nal_unit_type<=5)
return;
//for SPS and PPS, zero_byte shall exist
if(nalu->nal_unit_type==NALU_TYPE_SPS || nalu->nal_unit_type==NALU_TYPE_PPS)
CheckZeroByte=1;
//check the possibility of the current NALU to be the start of a new access unit, according to 7.4.1.2.3
if(nalu->nal_unit_type==NALU_TYPE_AUD || nalu->nal_unit_type==NALU_TYPE_SPS ||
nalu->nal_unit_type==NALU_TYPE_PPS || nalu->nal_unit_type==NALU_TYPE_SEI ||
(nalu->nal_unit_type>=13 && nalu->nal_unit_type<=18))
{
if(p_Vid->LastAccessUnitExists)
{
p_Vid->LastAccessUnitExists=0; //deliver the last access unit to decoder
p_Vid->NALUCount=0;
}
}
p_Vid->NALUCount++;
//for the first NAL unit in an access unit, zero_byte shall exists
if(p_Vid->NALUCount==1)
CheckZeroByte=1;
if(CheckZeroByte && nalu->startcodeprefix_len==3)
{
// printf("Warning: zero_byte shall exist\n");
//because it is not a very serious problem, we do not exit here
}
}
void CheckZeroByteVCL(VideoParameters *p_Vid, NALU_t *nalu)
{
int CheckZeroByte=0;
//This function deals only with VCL NAL units
if(!(nalu->nal_unit_type>=1&&nalu->nal_unit_type<=5))
return;
if(p_Vid->LastAccessUnitExists)
{
p_Vid->NALUCount=0;
}
p_Vid->NALUCount++;
//the first VCL NAL unit that is the first NAL unit after last VCL NAL unit indicates
//the start of a new access unit and hence the first NAL unit of the new access unit. (sounds like a tongue twister :-)
if(p_Vid->NALUCount == 1)
CheckZeroByte = 1;
p_Vid->LastAccessUnitExists = 1;
if(CheckZeroByte && nalu->startcodeprefix_len==3)
{
//printf("warning: zero_byte shall exist\n");
//because it is not a very serious problem, we do not exit here
}
}
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