/lencod/src/nal.c

/*!

 **************************************************************************************

 * \file

 *    nal.c

 * \brief

 *    Handles the operations on converting String of Data Bits (SODB)

 *    to Raw Byte Sequence Payload (RBSP), and then

 *    onto Encapsulate Byte Sequence Payload (EBSP).

 *  \date 14 June 2002

 * \author

 *    Main contributors (see contributors.h for copyright, address and affiliation details)

 *      - Shankar Regunathan                  <shanre@microsoft.de>

 *      - Stephan Wenger                      <stewe@cs.tu-berlin.de>

 ***************************************************************************************

 */



#include "contributors.h"

#include "global.h"

#include "enc_statistics.h"

#include "biariencode.h"

#include "nal.h"



static const int MbWidthC  [4]= { 0, 8, 8,  16};

static const int MbHeightC [4]= { 0, 8, 16, 16};



 /*!

 ************************************************************************

 * \brief

 *    Converts String Of Data Bits (SODB) to Raw Byte Sequence

 *    Packet (RBSP)

 * \param currStream

 *        Bitstream which contains data bits.

 * \return None

 * \note currStream is byte-aligned at the end of this function

 *

 ************************************************************************

*/



void SODBtoRBSP(Bitstream *currStream)

{

  currStream->byte_buf <<= 1;

  currStream->byte_buf |= 1;

  currStream->bits_to_go--;

  currStream->byte_buf <<= currStream->bits_to_go;

  currStream->streamBuffer[currStream->byte_pos++] = currStream->byte_buf;

  currStream->bits_to_go = 8;

  currStream->byte_buf = 0;

}





/*!

************************************************************************

*  \brief

*     This function add emulation_prevention_three_byte for all occurrences

*     of the following byte sequences in the stream

*       0x000000  -> 0x00000300

*       0x000001  -> 0x00000301

*       0x000002  -> 0x00000302

*       0x000003  -> 0x00000303

*

*  \param NaluBuffer

*            pointer to target buffer

*  \param rbsp

*            pointer to source buffer

*  \param rbsp_size

*           Size of source

*  \return

*           Size target buffer after emulation prevention.

*

************************************************************************

*/



int RBSPtoEBSP(byte *NaluBuffer, unsigned char *rbsp, int rbsp_size)

{

  int j     = 0;

  int count = 0;

  int i;



  for(i = 0; i < rbsp_size; i++)

  {

    if(count == ZEROBYTES_SHORTSTARTCODE && !(rbsp[i] & 0xFC))

    {

      NaluBuffer[j] = 0x03;

      j++;

      count = 0;

    }

    NaluBuffer[j] = rbsp[i];

    if(rbsp[i] == 0x00)

      count++;

    else

      count = 0;

    j++;

  }

  return j;

}



/*!

************************************************************************

*  \brief

*     This function adds cabac_zero_word syntax elements at the end of the

*     NAL unit to

*

*  \param p_Vid

*            VideoParameters structure

*  \param nalu

*            target NAL unit

*  \param cur_stats

*            currently used statistics parameters

*  \return

*           number of added bytes

*

************************************************************************

*/

int addCabacZeroWords(VideoParameters *p_Vid, NALU_t *nalu, StatParameters *cur_stats)

{

  seq_parameter_set_rbsp_t *active_sps = p_Vid->active_sps;



  int stuffing_bytes = 0;

  int i = 0;



  byte *buf = &nalu->buf[nalu->len];



  int RawMbBits = 256 * p_Vid->bitdepth_luma + 2 * MbWidthC[active_sps->chroma_format_idc] * MbHeightC[active_sps->chroma_format_idc] * p_Vid->bitdepth_chroma;

  int min_num_bytes = ((96 * get_pic_bin_count(p_Vid)) - (RawMbBits * (int)p_Vid->PicSizeInMbs *3) + 1023) / 1024;



  if (min_num_bytes > p_Vid->bytes_in_picture)

  {

    stuffing_bytes = min_num_bytes - p_Vid->bytes_in_picture;

    printf ("Inserting %d/%d cabac_zero_word syntax elements/bytes (Clause 7.4.2.10)\n", ((stuffing_bytes + 2)/3), stuffing_bytes);  



    for (i = 0; i < stuffing_bytes; i+=3 )

    {

      *buf++ = 0x00; // CABAC zero word

      *buf++ = 0x00;

      *buf++ = 0x03;

    }

    cur_stats->bit_use_stuffingBits[p_Vid->type] += (i<<3);

    nalu->len += i;

  }  



  return i;

}