source: SHVCSoftware/trunk/source/Lib/TLibEncoder/NALwrite.cpp @ 125

/* The copyright in this software is being made available under the BSD
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 * granted under this license.
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 * Copyright (c) 2010-2013, ITU/ISO/IEC
 * All rights reserved.
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 *    this list of conditions and the following disclaimer.
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 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
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 *    be used to endorse or promote products derived from this software without
 *    specific prior written permission.
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 */

#include <vector>
#include <algorithm>
#include <ostream>

#include "TLibCommon/NAL.h"
#include "TLibCommon/TComBitStream.h"
#include "NALwrite.h"

using namespace std;

//! \ingroup TLibEncoder
//! \{

static const Char emulation_prevention_three_byte[] = {3};

Void writeNalUnitHeader(ostream& out, OutputNALUnit& nalu)       // nal_unit_header()
{
TComOutputBitstream bsNALUHeader;

  bsNALUHeader.write(0,1);                    // forbidden_zero_bit
  bsNALUHeader.write(nalu.m_nalUnitType, 6);  // nal_unit_type
#if SVC_EXTENSION
  bsNALUHeader.write(nalu.m_layerId, 6); // reserved_one_5bits
#else
  bsNALUHeader.write(nalu.m_reservedZero6Bits, 6);                   // nuh_reserved_zero_6bits
#endif
  bsNALUHeader.write(nalu.m_temporalId+1, 3); // nuh_temporal_id_plus1

  out.write(bsNALUHeader.getByteStream(), bsNALUHeader.getByteStreamLength());
}
/**
 * write nalu to bytestream out, performing RBSP anti startcode
 * emulation as required.  nalu.m_RBSPayload must be byte aligned.
 */
void write(ostream& out, OutputNALUnit& nalu)
{
  writeNalUnitHeader(out, nalu);
  /* write out rsbp_byte's, inserting any required
   * emulation_prevention_three_byte's */
  /* 7.4.1 ...
   * emulation_prevention_three_byte is a byte equal to 0x03. When an
   * emulation_prevention_three_byte is present in the NAL unit, it shall be
   * discarded by the decoding process.
   * The last byte of the NAL unit shall not be equal to 0x00.
   * Within the NAL unit, the following three-byte sequences shall not occur at
   * any byte-aligned position:
   *  - 0x000000
   *  - 0x000001
   *  - 0x000002
   * Within the NAL unit, any four-byte sequence that starts with 0x000003
   * other than the following sequences shall not occur at any byte-aligned
   * position:
   *  - 0x00000300
   *  - 0x00000301
   *  - 0x00000302
   *  - 0x00000303
   */
  vector<uint8_t>& rbsp   = nalu.m_Bitstream.getFIFO();

  for (vector<uint8_t>::iterator it = rbsp.begin(); it != rbsp.end();)
  {
    /* 1) find the next emulated 00 00 {00,01,02,03}
     * 2a) if not found, write all remaining bytes out, stop.
     * 2b) otherwise, write all non-emulated bytes out
     * 3) insert emulation_prevention_three_byte
     */
    vector<uint8_t>::iterator found = it;
    do
    {
      /* NB, end()-1, prevents finding a trailing two byte sequence */
      found = search_n(found, rbsp.end()-1, 2, 0);
      found++;
      /* if not found, found == end, otherwise found = second zero byte */
      if (found == rbsp.end())
        break;
      if (*(++found) <= 3)
        break;
    } while (true);

    it = found;
    if (found != rbsp.end())
    {
      it = rbsp.insert(found, emulation_prevention_three_byte[0]);
    }
  }

  out.write((Char*)&(*rbsp.begin()), rbsp.end() - rbsp.begin());

  /* 7.4.1.1
   * ... when the last byte of the RBSP data is equal to 0x00 (which can
   * only occur when the RBSP ends in a cabac_zero_word), a final byte equal
   * to 0x03 is appended to the end of the data.
   */
  if (rbsp.back() == 0x00)
  {
    out.write(emulation_prevention_three_byte, 1);
  }
}

/**
 * Write rbsp_trailing_bits to bs causing it to become byte-aligned
 */
void writeRBSPTrailingBits(TComOutputBitstream& bs)
{
  bs.write( 1, 1 );
  bs.writeAlignZero();
}

/**
 * Copy NALU from naluSrc to naluDest
 */
void copyNaluData(OutputNALUnit& naluDest, const OutputNALUnit& naluSrc)
{
  naluDest.m_nalUnitType = naluSrc.m_nalUnitType;
  naluDest.m_reservedZero6Bits  = naluSrc.m_reservedZero6Bits;
  naluDest.m_temporalId  = naluSrc.m_temporalId;
  naluDest.m_Bitstream   = naluSrc.m_Bitstream;
#if SVC_EXTENSION
  naluDest.m_layerId   = naluSrc.m_layerId;
#endif
}

//! \}