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1085 | pj | 1 | /* systems.c, systems-specific routines */ |
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3 | /* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */ |
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4 | |||
5 | /* |
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6 | * Disclaimer of Warranty |
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7 | * |
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8 | * These software programs are available to the user without any license fee or |
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9 | * royalty on an "as is" basis. The MPEG Software Simulation Group disclaims |
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10 | * any and all warranties, whether express, implied, or statuary, including any |
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11 | * implied warranties or merchantability or of fitness for a particular |
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12 | * purpose. In no event shall the copyright-holder be liable for any |
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13 | * incidental, punitive, or consequential damages of any kind whatsoever |
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14 | * arising from the use of these programs. |
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15 | * |
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16 | * This disclaimer of warranty extends to the user of these programs and user's |
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17 | * customers, employees, agents, transferees, successors, and assigns. |
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18 | * |
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19 | * The MPEG Software Simulation Group does not represent or warrant that the |
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20 | * programs furnished hereunder are free of infringement of any third-party |
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21 | * patents. |
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22 | * |
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23 | * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware, |
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24 | * are subject to royalty fees to patent holders. Many of these patents are |
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25 | * general enough such that they are unavoidable regardless of implementation |
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26 | * design. |
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27 | * |
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28 | */ |
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29 | |||
30 | #include <stdio.h> |
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31 | #include <stdlib.h> |
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32 | |||
33 | #include "config.h" |
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34 | #include "global.h" |
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35 | |||
36 | /* initialize buffer, call once before first getbits or showbits */ |
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37 | |||
38 | /* parse system layer, ignore everything we don't need */ |
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39 | void Next_Packet() |
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40 | { |
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41 | unsigned int code; |
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42 | int l; |
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43 | |||
44 | for(;;) |
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45 | { |
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46 | code = Get_Long(); |
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47 | |||
48 | /* remove system layer byte stuffing */ |
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49 | while ((code & 0xffffff00) != 0x100) |
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50 | code = (code<<8) | Get_Byte(); |
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51 | |||
52 | switch(code) |
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53 | { |
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54 | case PACK_START_CODE: /* pack header */ |
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55 | /* skip pack header (system_clock_reference and mux_rate) */ |
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56 | ld->Rdptr += 8; |
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57 | break; |
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58 | case VIDEO_ELEMENTARY_STREAM: |
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59 | code = Get_Word(); /* packet_length */ |
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60 | ld->Rdmax = ld->Rdptr + code; |
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61 | |||
62 | code = Get_Byte(); |
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63 | |||
64 | if((code>>6)==0x02) |
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65 | { |
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66 | ld->Rdptr++; |
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67 | code=Get_Byte(); /* parse PES_header_data_length */ |
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68 | ld->Rdptr+=code; /* advance pointer by PES_header_data_length */ |
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69 | printf("MPEG-2 PES packet\n"); |
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70 | return; |
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71 | } |
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72 | else if(code==0xff) |
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73 | { |
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74 | /* parse MPEG-1 packet header */ |
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75 | while((code=Get_Byte())== 0xFF); |
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76 | } |
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77 | |||
78 | /* stuffing bytes */ |
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79 | if(code>=0x40) |
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80 | { |
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81 | if(code>=0x80) |
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82 | { |
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83 | fprintf(stderr,"Error in packet header\n"); |
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84 | exit(1); |
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85 | } |
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86 | /* skip STD_buffer_scale */ |
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87 | ld->Rdptr++; |
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88 | code = Get_Byte(); |
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89 | } |
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90 | |||
91 | if(code>=0x30) |
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92 | { |
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93 | if(code>=0x40) |
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94 | { |
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95 | fprintf(stderr,"Error in packet header\n"); |
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96 | exit(1); |
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97 | } |
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98 | /* skip presentation and decoding time stamps */ |
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99 | ld->Rdptr += 9; |
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100 | } |
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101 | else if(code>=0x20) |
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102 | { |
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103 | /* skip presentation time stamps */ |
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104 | ld->Rdptr += 4; |
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105 | } |
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106 | else if(code!=0x0f) |
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107 | { |
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108 | fprintf(stderr,"Error in packet header\n"); |
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109 | exit(1); |
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110 | } |
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111 | return; |
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112 | case ISO_END_CODE: /* end */ |
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113 | /* simulate a buffer full of sequence end codes */ |
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114 | l = 0; |
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115 | while (l<2048) |
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116 | { |
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117 | ld->Rdbfr[l++] = SEQUENCE_END_CODE>>24; |
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118 | ld->Rdbfr[l++] = SEQUENCE_END_CODE>>16; |
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119 | ld->Rdbfr[l++] = SEQUENCE_END_CODE>>8; |
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120 | ld->Rdbfr[l++] = SEQUENCE_END_CODE&0xff; |
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121 | } |
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122 | ld->Rdptr = ld->Rdbfr; |
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123 | ld->Rdmax = ld->Rdbfr + 2048; |
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124 | return; |
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125 | default: |
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126 | if(code>=SYSTEM_START_CODE) |
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127 | { |
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128 | /* skip system headers and non-video packets*/ |
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129 | code = Get_Word(); |
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130 | ld->Rdptr += code; |
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131 | } |
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132 | else |
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133 | { |
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134 | fprintf(stderr,"Unexpected startcode %08x in system layer\n",code); |
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135 | exit(1); |
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136 | } |
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137 | break; |
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138 | } |
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139 | } |
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140 | } |
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141 | |||
142 | |||
143 | |||
144 | void Flush_Buffer32() |
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145 | { |
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146 | int Incnt; |
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147 | |||
148 | ld->Bfr = 0; |
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149 | |||
150 | Incnt = ld->Incnt; |
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151 | Incnt -= 32; |
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152 | |||
153 | if (System_Stream_Flag && (ld->Rdptr >= ld->Rdmax-4)) |
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154 | { |
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155 | while (Incnt <= 24) |
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156 | { |
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157 | if (ld->Rdptr >= ld->Rdmax) |
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158 | Next_Packet(); |
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159 | ld->Bfr |= Get_Byte() << (24 - Incnt); |
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160 | Incnt += 8; |
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161 | } |
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162 | } |
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163 | else |
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164 | { |
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165 | while (Incnt <= 24) |
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166 | { |
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167 | if (ld->Rdptr >= ld->Rdbfr+2048) |
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168 | Fill_Buffer(); |
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169 | ld->Bfr |= *ld->Rdptr++ << (24 - Incnt); |
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170 | Incnt += 8; |
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171 | } |
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172 | } |
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173 | ld->Incnt = Incnt; |
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174 | |||
175 | #ifdef VERIFY |
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176 | ld->Bitcnt += 32; |
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177 | #endif /* VERIFY */ |
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178 | } |
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179 | |||
180 | |||
181 | unsigned int Get_Bits32() |
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182 | { |
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183 | unsigned int l; |
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184 | |||
185 | l = Show_Bits(32); |
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186 | Flush_Buffer32(); |
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187 | |||
188 | return l; |
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189 | } |
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190 | |||
191 | |||
192 | int Get_Long() |
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193 | { |
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194 | int i; |
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195 | |||
196 | i = Get_Word(); |
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197 | return (i<<16) | Get_Word(); |
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198 | } |
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199 | |||
200 |