annexb.c

包含了从MPEG4的视频解码到H.264的视频编码部分的源代码

/*
***********************************************************************
* COPYRIGHT AND WARRANTY INFORMATION
*
* Copyright 2001, International Telecommunications Union, Geneva
*
* DISCLAIMER OF WARRANTY
*
* These software programs are available to the user without any
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* contributor or the ITU be liable for any incidental, punitive, or
* consequential damages of any kind whatsoever arising from the
* use of these programs.
*
* This disclaimer of warranty extends to the user of these programs
* and user's customers, employees, agents, transferees, successors,
* and assigns.
*
* The ITU does not represent or warrant that the programs furnished
* hereunder are free of infringement of any third-party patents.
* Commercial implementations of ITU-T Recommendations, including
* shareware, may be subject to royalty fees to patent holders.
* Information regarding the ITU-T patent policy is available from
* the ITU Web site at http://www.itu.int.
*
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************************************************************************
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/*!
 *************************************************************************************
 * \file annexb.c
 *
 * \brief
 *    Annex B Byte Stream format NAL Unit writing routines
 *
 * \author
 *    Main contributors (see contributors.h for copyright, address and affiliation details)
 *      - Stephan Wenger                  <[e-mail]>
 *************************************************************************************
 */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "global.h"
#include "nalucommon.h"

static FILE *f = NULL;    // the output file


/*!
 ********************************************************************************************
 * \brief 
 *    Writes a NALU to the Annex B Byte Stream
 *
 * \return
 *    number of bits written
 *
 ********************************************************************************************
*/
int WriteAnnexbNALU (NALU_t *n)
{
  int BitsWritten = 0;

  assert (n != NULL);
  assert (n->forbidden_bit == 0);
  assert (f != NULL);
  assert (n->startcodeprefix_len == 3 || n->startcodeprefix_len == 4);

// printf ("WriteAnnexbNALU: writing %d bytes w/ startcode_len %d\n", n->len+1, n->startcodeprefix_len); 
  if (n->startcodeprefix_len > 3)
  {
    putc (0, f);
    BitsWritten =+ 8;
  }
  putc (0, f);
  putc (0, f);
  putc (1, f);
  BitsWritten += 24;

  n->buf[0] =
    n->forbidden_bit << 7      |
    n->nal_reference_idc << 5  |
    n->nal_unit_type;

// printf ("First Byte %x, nal_ref_idc %x, nal_unit_type %d\n", n->buf[0], n->nal_reference_idc, n->nal_unit_type);

  if (n->len != fwrite (n->buf, 1, n->len, f))
  {
    printf ("Fatal: cannot write %d bytes to bitstream file, exit (-1)\n", n->len);
    exit (-1);
  }
  BitsWritten += n->len * 8;

  fflush (f);
#if TRACE
  fprintf (p_trace, "\n\nAnnex B NALU w/ %s startcode, len %d, forbidden_bit %d, nal_reference_idc %d, nal_unit_type %d\n\n",
    n->startcodeprefix_len == 4?"long":"short", n->len, n->forbidden_bit, n->nal_reference_idc, n->nal_unit_type);
  fflush (p_trace);
#endif
  return BitsWritten;
}


/*!
 ********************************************************************************************
 * \brief 
 *    Opens the output file for the bytestream    
 *
 * \param 
 *    The filename of the file to be opened
 *
 * \return
 *    none.  Function terminates the program in case of an error
 *
 ********************************************************************************************
*/
void OpenAnnexbFile (char *Filename)
{
  if ((f = fopen (Filename, "wb")) == NULL)
  {
    printf ("Fatal: cannot open Annex B bytestream file '%s', exit (-1)\n", Filename);
    exit (-1);
  }
}


/*!
 ********************************************************************************************
 * \brief 
 *    Closes the output bit stream file
 *
 * \return
 *    none.  Funtion trerminates the program in case of an error
 ********************************************************************************************
*/
void CloseAnnexbFile() {
  if (fclose (f))
  {
    printf ("Fatal: cannot close Annex B bytestream file, exit (-1)\n");
    exit (-1);
  }
}