src/dsutil/H264Nalu.cpp

   1 /*
   2  * (C) 2006-2012 see Authors.txt
   3  *
   4  * This file is part of MPC-HC.
   5  *
   6  * MPC-HC is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * MPC-HC is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "stdafx.h"
  22 #include "H264Nalu.h"
  23
  24 void CH264Nalu::SetBuffer(BYTE* pBuffer, int nSize, int nNALSize)
  25 {
  26     m_pBuffer       = pBuffer;
  27     m_nSize         = nSize;
  28     m_nNALSize      = nNALSize;
  29     m_nCurPos       = 0;
  30     m_nNextRTP      = 0;
  31
  32     m_nNALStartPos  = 0;
  33     m_nNALDataPos   = 0;
  34
  35     if (!nNALSize && nSize) {
  36         MoveToNextAnnexBStartcode();
  37     }
  38 }
  39
  40 bool CH264Nalu::MoveToNextAnnexBStartcode()
  41 {
  42     int nBuffEnd = m_nSize - 4;
  43
  44     for (int i = m_nCurPos; i < nBuffEnd; i++) {
  45         if ((*((DWORD*)(m_pBuffer + i)) & 0x00FFFFFF) == 0x00010000) {
  46             // Find next AnnexB Nal
  47             m_nCurPos = i;
  48             return true;
  49         }
  50     }
  51
  52     m_nCurPos = m_nSize;
  53     return false;
  54 }
  55
  56 bool CH264Nalu::MoveToNextRTPStartcode()
  57 {
  58     if (m_nNextRTP < m_nSize) {
  59         m_nCurPos = m_nNextRTP;
  60         return true;
  61     }
  62
  63     m_nCurPos = m_nSize;
  64     return false;
  65 }
  66
  67 bool CH264Nalu::ReadNext()
  68 {
  69     if ((m_nCurPos >= m_nSize) || (m_nCurPos < 0)) {
  70         return false;
  71     }
  72
  73     if ((m_nNALSize != 0) && (m_nCurPos == m_nNextRTP)) {
  74         // RTP Nalu type : (XX XX) XX XX NAL..., with XX XX XX XX or XX XX equal to NAL size
  75         m_nNALStartPos = m_nCurPos;
  76         m_nNALDataPos  = m_nCurPos + m_nNALSize;
  77         unsigned nTemp = 0;
  78         for (int i = 0; i < m_nNALSize; i++) {
  79             nTemp = (nTemp << 8) + m_pBuffer[m_nCurPos++];
  80         }
  81         m_nNextRTP += nTemp + m_nNALSize;
  82         MoveToNextRTPStartcode();
  83     } else {
  84         // Remove trailing bits
  85         while (m_pBuffer[m_nCurPos] == 0x00 && ((*((DWORD*)(m_pBuffer + m_nCurPos)) & 0x00FFFFFF) != 0x00010000)) {
  86             m_nCurPos++;
  87         }
  88
  89         // AnnexB Nalu : 00 00 01 NAL...
  90         m_nNALStartPos = m_nCurPos;
  91         m_nCurPos     += 3;
  92         m_nNALDataPos  = m_nCurPos;
  93         MoveToNextAnnexBStartcode();
  94     }
  95
  96     forbidden_bit     = (m_pBuffer[m_nNALDataPos] >> 7) & 1;
  97     nal_reference_idc = (m_pBuffer[m_nNALDataPos] >> 5) & 3;
  98     nal_unit_type     = (NALU_TYPE)(m_pBuffer[m_nNALDataPos] & 0x1f);
  99
 100     return true;
 101 }