NAL.h

/* The copyright in this software is being made available under the BSD
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 * Copyright (c) 2010-2023, ITU/ISO/IEC
 * All rights reserved.
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 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#ifndef __NAL__
#define __NAL__

#include <sstream>
#include <list>
#include "CommonDef.h"

class OutputBitstream;

/**
 * Represents a single NALunit header and the associated RBSPayload
 */
struct NALUnit
{
  NalUnitType m_nalUnitType; ///< nal_unit_type
  uint32_t        m_temporalId;  ///< temporal_id
  uint32_t        m_nuhLayerId;  ///< nuh_layer_id
  uint32_t        m_forbiddenZeroBit;
  uint32_t        m_nuhReservedZeroBit;

  NALUnit(const NALUnit &src)
  :m_nalUnitType (src.m_nalUnitType)
  ,m_temporalId  (src.m_temporalId)
  ,m_nuhLayerId  (src.m_nuhLayerId)
  , m_forbiddenZeroBit(src.m_forbiddenZeroBit)
  , m_nuhReservedZeroBit(src.m_nuhReservedZeroBit)
  { }
  /** construct an NALunit structure with given header values. */
  NALUnit(NalUnitType nalUnitType, int temporalId = 0, uint32_t nuhReservedZeroBit = 0, uint32_t forbiddenZeroBit = 0,
          int nuhLayerId = 0)
    : m_nalUnitType(nalUnitType)
    , m_temporalId(temporalId)
    , m_nuhLayerId(nuhLayerId)
    , m_forbiddenZeroBit(forbiddenZeroBit)
    , m_nuhReservedZeroBit(nuhReservedZeroBit)
  {}

  /** default constructor - no initialization; must be performed by user */
  NALUnit() {}

  virtual ~NALUnit() { }

  /** returns true if the NALunit is a slice NALunit */
  bool isSlice()
  {
    return m_nalUnitType == NAL_UNIT_CODED_SLICE_TRAIL
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_STSA
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_IDR_W_RADL
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_IDR_N_LP
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_CRA
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_GDR
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_RADL
        || m_nalUnitType == NAL_UNIT_CODED_SLICE_RASL;
  }
  bool isSei()
  {
    return m_nalUnitType == NAL_UNIT_PREFIX_SEI
        || m_nalUnitType == NAL_UNIT_SUFFIX_SEI;
  }

  bool isVcl()
  {
    return isVclNalUnitType(m_nalUnitType);
  }

  static bool isVclNalUnitType(NalUnitType t)
  {
    return t == NAL_UNIT_CODED_SLICE_TRAIL
        || t == NAL_UNIT_CODED_SLICE_STSA
        || t == NAL_UNIT_CODED_SLICE_RADL
        || t == NAL_UNIT_CODED_SLICE_RASL
        || t == NAL_UNIT_CODED_SLICE_IDR_W_RADL
        || t == NAL_UNIT_CODED_SLICE_IDR_N_LP
        || t == NAL_UNIT_CODED_SLICE_CRA
        || t == NAL_UNIT_CODED_SLICE_GDR;
  }
};

struct OutputNALUnit;

/**
 * A single NALunit, with complete payload in EBSP format.
 */
struct NALUnitEBSP : public NALUnit
{
  std::ostringstream m_nalUnitData;

  /**
   * convert the OutputNALUnit nalu into EBSP format by writing out
   * the NALUnit header, then the rbsp_bytes including any
   * emulation_prevention_three_byte symbols.
   */
  NALUnitEBSP(OutputNALUnit& nalu);
};
//! \}
//! \}


/**
 * An AccessUnit is a list of one or more NAL units, according to the
 * working draft.  All NAL units within the object belong to the same
 * access unit.
 *
 * NALUnits held in the AccessUnit list are in EBSP format.  Attempting
 * to insert an OutputNALUnit into the access unit will automatically cause
 * the nalunit to have its headers written and anti-emulation performed.
 *
 * The AccessUnit owns all pointers stored within.  Destroying the
 * AccessUnit will delete all contained objects.
 */
class AccessUnit : public std::list<NALUnitEBSP*> // NOTE: Should not inherit from STL.
{
public:
  int temporalId;
  ~AccessUnit()
  {
    for (AccessUnit::iterator it = this->begin(); it != this->end(); it++)
    {
      delete *it;
    }
  }
};


#endif