H.264/AVC Reference Software Encoder: nalu.c Source File

00001 
00002 /*!
00003  ************************************************************************
00004  * \file  nalu.c
00005  *
00006  * \brief
00007  *    Common NALU support functions
00008  *
00009  * \author
00010  *    Main contributors (see contributors.h for copyright, address and affiliation details)
00011  *    - Stephan Wenger   <stewe@cs.tu-berlin.de>
00012  ************************************************************************
00013  */
00014 
00015 #include "global.h"
00016 #include "nalu.h"
00017 #include "nal.h"
00018 
00019 /*!
00020  *************************************************************************************
00021  * \brief
00022  *    Converts an RBSP to a NALU
00023  *
00024  * \param rbsp
00025  *    byte buffer with the rbsp
00026  * \param nalu
00027  *    nalu structure to be filled
00028  * \param rbsp_size
00029  *    size of the rbsp in bytes
00030  * \param nal_unit_type
00031  *    as in JVT doc
00032  * \param nal_reference_idc
00033  *    as in JVT doc
00034  * \param min_num_bytes
00035  *    some incomprehensible CABAC stuff
00036  * \param UseAnnexbLongStartcode
00037  *    when 1 and when using AnnexB bytestreams, then use a long startcode prefix
00038  *
00039  * \return
00040  *    length of the NALU in bytes
00041  *************************************************************************************
00042  */
00043 
00044 int RBSPtoNALU (unsigned char *rbsp, NALU_t *nalu, int rbsp_size, int nal_unit_type, int nal_reference_idc,
00045                 int min_num_bytes, int UseAnnexbLongStartcode)
00046 {
00047   int len;
00048 
00049   assert (nalu != NULL);
00050   assert (nal_reference_idc <=3 && nal_reference_idc >=0);
00051   assert (nal_unit_type > 0 && nal_unit_type <= 10);
00052   assert (rbsp_size < MAXRBSPSIZE);
00053   
00054   nalu->startcodeprefix_len = UseAnnexbLongStartcode ? 4 : 3;
00055   nalu->forbidden_bit       = 0;  
00056   nalu->nal_reference_idc   = (NalRefIdc) nal_reference_idc;
00057   nalu->nal_unit_type       = (NaluType) nal_unit_type;    
00058 
00059   len = RBSPtoEBSP (nalu->buf, rbsp, rbsp_size);
00060   nalu->len = len;
00061 
00062   return len;
00063 }
00064 
00065 /*!
00066  ************************************************************************
00067  *  \brief
00068  *     write AUD NALU
00069  ************************************************************************
00070  */
00071 
00072 int Write_AUD_NALU( void )
00073 {  
00074   int     RBSPlen = 0;
00075   int     NALUlen, len;
00076   byte    rbsp[MAXRBSPSIZE];
00077   NALU_t *nalu = AllocNALU( 64000 );
00078 
00079   switch( img->type )
00080   {
00081   case I_SLICE:
00082     img->primary_pic_type = 0;
00083     break;
00084   case P_SLICE:
00085     img->primary_pic_type = 1;
00086     break;
00087   case B_SLICE:
00088     img->primary_pic_type = 2;
00089     break;
00090   }
00091   RBSPlen = 1;
00092   rbsp[0] = img->primary_pic_type << 5;
00093   rbsp[0] |= (1 << 4);
00094 
00095   // write RBSP into NALU
00096   NALUlen = RBSPtoNALU( rbsp, nalu, RBSPlen, NALU_TYPE_AUD, NALU_PRIORITY_HIGHEST, 0, 1 );
00097   // write NALU into bitstream
00098   len     = WriteNALU( nalu );
00099 
00100   FreeNALU( nalu );
00101 
00102   return len;
00103 }