xbmc/utils/VC1BitstreamParser.cpp

   1 /*
   2  *  Copyright (C) 2017-2018 Team Kodi
   3  *  This file is part of Kodi - https://kodi.tv
   4  *
   5  *  SPDX-License-Identifier: GPL-2.0-or-later
   6  *  See LICENSES/README.md for more information.
   7  */
   8
   9 #include "VC1BitstreamParser.h"
  10
  11 #include "BitstreamReader.h"
  12
  13 enum
  14 {
  15   VC1_PROFILE_SIMPLE,
  16   VC1_PROFILE_MAIN,
  17   VC1_PROFILE_RESERVED,
  18   VC1_PROFILE_ADVANCED,
  19   VC1_PROFILE_NOPROFILE
  20 };
  21
  22 enum
  23 {
  24   VC1_END_OF_SEQ = 0x0A,
  25   VC1_SLICE = 0x0B,
  26   VC1_FIELD = 0x0C,
  27   VC1_FRAME = 0x0D,
  28   VC1_ENTRYPOINT = 0x0E,
  29   VC1_SEQUENCE = 0x0F,
  30   VC1_SLICE_USER = 0x1B,
  31   VC1_FIELD_USER = 0x1C,
  32   VC1_FRAME_USER = 0x1D,
  33   VC1_ENTRY_POINT_USER = 0x1E,
  34   VC1_SEQUENCE_USER = 0x1F
  35 };
  36
  37 enum
  38 {
  39   VC1_FRAME_PROGRESSIVE = 0x0,
  40   VC1_FRAME_INTERLACE = 0x10,
  41   VC1_FIELD_INTERLACE = 0x11
  42 };
  43
  44 CVC1BitstreamParser::CVC1BitstreamParser()
  45 {
  46   Reset();
  47 }
  48
  49 void CVC1BitstreamParser::Reset()
  50 {
  51   m_Profile = VC1_PROFILE_NOPROFILE;
  52 }
  53
  54 bool CVC1BitstreamParser::IsRecoveryPoint(const uint8_t *buf, int buf_size)
  55 {
  56   return vc1_parse_frame(buf, buf + buf_size, true);
  57 };
  58
  59 bool CVC1BitstreamParser::IsIFrame(const uint8_t *buf, int buf_size)
  60 {
  61   return vc1_parse_frame(buf, buf + buf_size, false);
  62 };
  63
  64 bool CVC1BitstreamParser::vc1_parse_frame(const uint8_t *buf, const uint8_t *buf_end, bool sequence_only)
  65 {
  66   uint32_t state = -1;
  67   for (;;)
  68   {
  69     buf = find_start_code(buf, buf_end, &state);
  70     if (buf >= buf_end)
  71       break;
  72     if (buf[-1] == VC1_SEQUENCE)
  73     {
  74       if (m_Profile != VC1_PROFILE_NOPROFILE)
  75         return false;
  76       CBitstreamReader br(buf, buf_end - buf);
  77       // Read the profile
  78       m_Profile = static_cast<uint8_t>(br.ReadBits(2));
  79       if (m_Profile == VC1_PROFILE_ADVANCED)
  80       {
  81         br.SkipBits(39);
  82         m_AdvInterlace = br.ReadBits(1);
  83       }
  84       else
  85       {
  86         br.SkipBits(22);
  87
  88         m_SimpleSkipBits = 2;
  89         if (br.ReadBits(1)) //rangered
  90           ++m_SimpleSkipBits;
  91
  92         m_MaxBFrames = br.ReadBits(3);
  93
  94         br.SkipBits(2); // quantizer
  95         if (br.ReadBits(1)) //finterpflag
  96           ++m_SimpleSkipBits;
  97       }
  98       if (sequence_only)
  99         return true;
 100     }
 101     else if (buf[-1] == VC1_FRAME)
 102     {
 103       CBitstreamReader br(buf, buf_end - buf);
 104
 105       if (sequence_only)
 106         return false;
 107       if (m_Profile == VC1_PROFILE_ADVANCED)
 108       {
 109         uint8_t fcm;
 110         if (m_AdvInterlace) {
 111           fcm = br.ReadBits(1);
 112           if (fcm)
 113             fcm = br.ReadBits(1) + 1;
 114         }
 115         else
 116           fcm = VC1_FRAME_PROGRESSIVE;
 117         if (fcm == VC1_FIELD_INTERLACE) {
 118           uint8_t pic = br.ReadBits(3);
 119           return pic == 0x00 || pic == 0x01;
 120         }
 121         else
 122         {
 123           uint8_t pic(0);
 124           while (pic < 4 && br.ReadBits(1))++pic;
 125           return pic == 2;
 126         }
 127         return false;
 128       }
 129       else if (m_Profile != VC1_PROFILE_NOPROFILE)
 130       {
 131         br.SkipBits(m_SimpleSkipBits); // quantizer
 132         uint8_t pic(br.ReadBits(1));
 133         if (m_MaxBFrames) {
 134           if (!pic) {
 135             pic = br.ReadBits(1);
 136             return pic != 0;
 137           }
 138           else
 139             return false;
 140         }
 141         else
 142           return pic != 0;
 143       }
 144       else
 145         break;
 146     }
 147   }
 148   return false;
 149 }