?? getvlc.c
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/* getvlc.c, 可變長編碼的解碼 */#include <stdio.h>#include "config.h"#include "global.h"#include "getvlc.h"/* private prototypes *//* generic picture macroblock type processing functions */static int Get_I_macroblock_type _ANSI_ARGS_((void));static int Get_P_macroblock_type _ANSI_ARGS_((void));static int Get_B_macroblock_type _ANSI_ARGS_((void));static int Get_D_macroblock_type _ANSI_ARGS_((void));/* spatial picture macroblock type processing functions */static int Get_I_Spatial_macroblock_type _ANSI_ARGS_((void));static int Get_P_Spatial_macroblock_type _ANSI_ARGS_((void));static int Get_B_Spatial_macroblock_type _ANSI_ARGS_((void));static int Get_SNR_macroblock_type _ANSI_ARGS_((void));int Get_macroblock_type(){ int macroblock_type = 0; if (ld->scalable_mode==SC_SNR) macroblock_type = Get_SNR_macroblock_type(); else { switch (picture_coding_type) { case I_TYPE: macroblock_type = ld->pict_scal ? Get_I_Spatial_macroblock_type() : Get_I_macroblock_type(); break; case P_TYPE: macroblock_type = ld->pict_scal ? Get_P_Spatial_macroblock_type() : Get_P_macroblock_type(); break; case B_TYPE: macroblock_type = ld->pict_scal ? Get_B_Spatial_macroblock_type() : Get_B_macroblock_type(); break; case D_TYPE: macroblock_type = Get_D_macroblock_type(); break; default: printf("Get_macroblock_type(): unrecognized picture coding type\n"); break; } } return macroblock_type;}static int Get_I_macroblock_type(){#ifdef TRACE if (Trace_Flag) printf("macroblock_type(I) ");#endif /* TRACE */ if (Get_Bits1()) {#ifdef TRACE if (Trace_Flag) printf("(1): Intra (1)\n");#endif /* TRACE */ return 1; } if (!Get_Bits1()) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; }#ifdef TRACE if (Trace_Flag) printf("(01): Intra, Quant (17)\n");#endif /* TRACE */ return 17;}static char *MBdescr[]={ "", "Intra", "No MC, Coded", "", "Bwd, Not Coded", "", "Bwd, Coded", "", "Fwd, Not Coded", "", "Fwd, Coded", "", "Interp, Not Coded", "", "Interp, Coded", "", "", "Intra, Quant", "No MC, Coded, Quant", "", "", "", "Bwd, Coded, Quant", "", "", "", "Fwd, Coded, Quant", "", "", "", "Interp, Coded, Quant", ""};static int Get_P_macroblock_type(){ int code;#ifdef TRACE if (Trace_Flag) printf("macroblock_type(P) (");#endif /* TRACE */ if ((code = Show_Bits(6))>=8) { code >>= 3; Flush_Buffer(PMBtab0[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,3,PMBtab0[code].len); printf("): %s (%d)\n",MBdescr[(int)PMBtab0[code].val],PMBtab0[code].val); }#endif /* TRACE */ return PMBtab0[code].val; } if (code==0) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; return 0; } Flush_Buffer(PMBtab1[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,6,PMBtab1[code].len); printf("): %s (%d)\n",MBdescr[(int)PMBtab1[code].val],PMBtab1[code].val); }#endif /* TRACE */ return PMBtab1[code].val;}static int Get_B_macroblock_type(){ int code;#ifdef TRACE if (Trace_Flag) printf("macroblock_type(B) (");#endif /* TRACE */ if ((code = Show_Bits(6))>=8) { code >>= 2; Flush_Buffer(BMBtab0[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,4,BMBtab0[code].len); printf("): %s (%d)\n",MBdescr[(int)BMBtab0[code].val],BMBtab0[code].val); }#endif /* TRACE */ return BMBtab0[code].val; } if (code==0) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; return 0; } Flush_Buffer(BMBtab1[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,6,BMBtab1[code].len); printf("): %s (%d)\n",MBdescr[(int)BMBtab1[code].val],BMBtab1[code].val); }#endif /* TRACE */ return BMBtab1[code].val;}static int Get_D_macroblock_type(){ if (!Get_Bits1()) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag=1; } return 1;}/* macroblock_type for pictures with spatial scalability */static int Get_I_Spatial_macroblock_type(){ int code;#ifdef TRACE if (Trace_Flag) printf("macroblock_type(I,spat) (");#endif /* TRACE */ code = Show_Bits(4); if (code==0) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; return 0; }#ifdef TRACE if (Trace_Flag) { Print_Bits(code,4,spIMBtab[code].len); printf("): %02x\n",spIMBtab[code].val); }#endif /* TRACE */ Flush_Buffer(spIMBtab[code].len); return spIMBtab[code].val;}static int Get_P_Spatial_macroblock_type(){ int code;#ifdef TRACE if (Trace_Flag) printf("macroblock_type(P,spat) (");#endif /* TRACE */ code = Show_Bits(7); if (code<2) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; return 0; } if (code>=16) { code >>= 3; Flush_Buffer(spPMBtab0[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,4,spPMBtab0[code].len); printf("): %02x\n",spPMBtab0[code].val); }#endif /* TRACE */ return spPMBtab0[code].val; } Flush_Buffer(spPMBtab1[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,7,spPMBtab1[code].len); printf("): %02x\n",spPMBtab1[code].val); }#endif /* TRACE */ return spPMBtab1[code].val;}static int Get_B_Spatial_macroblock_type(){ int code; VLCtab *p;#ifdef TRACE if (Trace_Flag) printf("macroblock_type(B,spat) (");#endif /* TRACE */ code = Show_Bits(9); if (code>=64) p = &spBMBtab0[(code>>5)-2]; else if (code>=16) p = &spBMBtab1[(code>>2)-4]; else if (code>=8) p = &spBMBtab2[code-8]; else { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; return 0; } Flush_Buffer(p->len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,9,p->len); printf("): %02x\n",p->val); }#endif /* TRACE */ return p->val;}static int Get_SNR_macroblock_type(){ int code;#ifdef TRACE /* *CH* */ if (Trace_Flag) printf("macroblock_type(SNR) (");#endif TRACE code = Show_Bits(3); if (code==0) { if (!Quiet_Flag) printf("Invalid macroblock_type code\n"); Fault_Flag = 1; return 0; } Flush_Buffer(SNRMBtab[code].len);#ifdef TRACE /* *CH* */ if (Trace_Flag) { Print_Bits(code,3,SNRMBtab[code].len); printf("): %s (%d)\n",MBdescr[(int)SNRMBtab[code].val],SNRMBtab[code].val); }#endif TRACE return SNRMBtab[code].val;}int Get_motion_code(){ int code;#ifdef TRACE if (Trace_Flag) printf("motion_code (");#endif /* TRACE */ if (Get_Bits1()) {#ifdef TRACE if (Trace_Flag) printf("0): 0\n");#endif /* TRACE */ return 0; } if ((code = Show_Bits(9))>=64) { code >>= 6; Flush_Buffer(MVtab0[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,3,MVtab0[code].len); printf("%d): %d\n", Show_Bits(1),Show_Bits(1)?-MVtab0[code].val:MVtab0[code].val); }#endif /* TRACE */ return Get_Bits1()?-MVtab0[code].val:MVtab0[code].val; } if (code>=24) { code >>= 3; Flush_Buffer(MVtab1[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,6,MVtab1[code].len); printf("%d): %d\n", Show_Bits(1),Show_Bits(1)?-MVtab1[code].val:MVtab1[code].val); }#endif /* TRACE */ return Get_Bits1()?-MVtab1[code].val:MVtab1[code].val; } if ((code-=12)<0) { if (!Quiet_Flag)/* HACK */ printf("Invalid motion_vector code (MBA %d, pic %d)\n", global_MBA, global_pic); Fault_Flag=1; return 0; } Flush_Buffer(MVtab2[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code+12,9,MVtab2[code].len); printf("%d): %d\n", Show_Bits(1),Show_Bits(1)?-MVtab2[code].val:MVtab2[code].val); }#endif /* TRACE */ return Get_Bits1() ? -MVtab2[code].val : MVtab2[code].val;}/* get differential motion vector (for dual prime prediction) */int Get_dmvector(){#ifdef TRACE if (Trace_Flag) printf("dmvector (");#endif /* TRACE */ if (Get_Bits(1)) {#ifdef TRACE if (Trace_Flag) printf(Show_Bits(1) ? "11): -1\n" : "10): 1\n");#endif /* TRACE */ return Get_Bits(1) ? -1 : 1; } else {#ifdef TRACE if (Trace_Flag) printf("0): 0\n");#endif /* TRACE */ return 0; }}int Get_coded_block_pattern(){ int code;#ifdef TRACE if (Trace_Flag) printf("coded_block_pattern_420 (");#endif /* TRACE */ if ((code = Show_Bits(9))>=128) { code >>= 4; Flush_Buffer(CBPtab0[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,5,CBPtab0[code].len); printf("): "); Print_Bits(CBPtab0[code].val,6,6); printf(" (%d)\n",CBPtab0[code].val); }#endif /* TRACE */ return CBPtab0[code].val; } if (code>=8) { code >>= 1; Flush_Buffer(CBPtab1[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,8,CBPtab1[code].len); printf("): "); Print_Bits(CBPtab1[code].val,6,6); printf(" (%d)\n",CBPtab1[code].val); }#endif /* TRACE */ return CBPtab1[code].val; } if (code<1) { if (!Quiet_Flag) printf("Invalid coded_block_pattern code\n"); Fault_Flag = 1; return 0; } Flush_Buffer(CBPtab2[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,9,CBPtab2[code].len); printf("): "); Print_Bits(CBPtab2[code].val,6,6); printf(" (%d)\n",CBPtab2[code].val); }#endif /* TRACE */ return CBPtab2[code].val;}int Get_macroblock_address_increment(){ int code, val;#ifdef TRACE if (Trace_Flag) printf("macroblock_address_increment (");#endif /* TRACE */ val = 0; while ((code = Show_Bits(11))<24) { if (code!=15) /* if not macroblock_stuffing */ { if (code==8) /* if macroblock_escape */ {#ifdef TRACE if (Trace_Flag) printf("00000001000 ");#endif /* TRACE */ val+= 33; } else { if (!Quiet_Flag) printf("Invalid macroblock_address_increment code\n"); Fault_Flag = 1; return 1; } } else /* macroblock suffing */ {#ifdef TRACE if (Trace_Flag) printf("00000001111 ");#endif /* TRACE */ } Flush_Buffer(11); } /* macroblock_address_increment == 1 */ /* ('1' is in the MSB position of the lookahead) */ if (code>=1024) { Flush_Buffer(1);#ifdef TRACE if (Trace_Flag) printf("1): %d\n",val+1);#endif /* TRACE */ return val + 1; } /* codes 00010 ... 011xx */ if (code>=128) { /* remove leading zeros */ code >>= 6; Flush_Buffer(MBAtab1[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code,5,MBAtab1[code].len); printf("): %d\n",val+MBAtab1[code].val); }#endif /* TRACE */ return val + MBAtab1[code].val; } /* codes 00000011000 ... 0000111xxxx */ code-= 24; /* remove common base */ Flush_Buffer(MBAtab2[code].len);#ifdef TRACE if (Trace_Flag) { Print_Bits(code+24,11,MBAtab2[code].len); printf("): %d\n",val+MBAtab2[code].val); }#endif /* TRACE */ return val + MBAtab2[code].val;}/* combined MPEG-1 and MPEG-2 stage. parse VLC and perform dct_diff arithmetic. MPEG-1: ISO/IEC 11172-2 section MPEG-2: ISO/IEC 13818-2 section 7.2.1 Note: the arithmetic here is presented more elegantly than the spec, yet the results, dct_diff, are the same.*/int Get_Luma_DC_dct_diff(){ int code, size, dct_diff;#ifdef TRACE/* if (Trace_Flag) printf("dct_dc_size_luminance: (");*/#endif /* TRACE */ /* decode length */ code = Show_Bits(5); if (code<31) { size = DClumtab0[code].val; Flush_Buffer(DClumtab0[code].len);#ifdef TRACE/* if (Trace_Flag) { Print_Bits(code,5,DClumtab0[code].len); printf("): %d",size); }*/#endif /* TRACE */ } else { code = Show_Bits(9) - 0x1f0; size = DClumtab1[code].val; Flush_Buffer(DClumtab1[code].len);#ifdef TRACE/* if (Trace_Flag) { Print_Bits(code+0x1f0,9,DClumtab1[code].len); printf("): %d",size); }*/#endif /* TRACE */ }#ifdef TRACE/* if (Trace_Flag) printf(", dct_dc_differential (");*/#endif /* TRACE */ if (size==0) dct_diff = 0; else { dct_diff = Get_Bits(size);#ifdef TRACE/* if (Trace_Flag) Print_Bits(dct_diff,size,size);*/#endif /* TRACE */ if ((dct_diff & (1<<(size-1)))==0) dct_diff-= (1<<size) - 1; }#ifdef TRACE/* if (Trace_Flag) printf("): %d\n",dct_diff);*/#endif /* TRACE */ return dct_diff;}int Get_Chroma_DC_dct_diff(){ int code, size, dct_diff;#ifdef TRACE/* if (Trace_Flag) printf("dct_dc_size_chrominance: (");*/#endif /* TRACE */ /* decode length */ code = Show_Bits(5); if (code<31) { size = DCchromtab0[code].val; Flush_Buffer(DCchromtab0[code].len);#ifdef TRACE/* if (Trace_Flag) { Print_Bits(code,5,DCchromtab0[code].len); printf("): %d",size); }*/#endif /* TRACE */ } else { code = Show_Bits(10) - 0x3e0; size = DCchromtab1[code].val; Flush_Buffer(DCchromtab1[code].len);#ifdef TRACE/* if (Trace_Flag) { Print_Bits(code+0x3e0,10,DCchromtab1[code].len); printf("): %d",size); }*/#endif /* TRACE */ }#ifdef TRACE/* if (Trace_Flag) printf(", dct_dc_differential (");*/#endif /* TRACE */ if (size==0) dct_diff = 0; else { dct_diff = Get_Bits(size);#ifdef TRACE/* if (Trace_Flag) Print_Bits(dct_diff,size,size);*/#endif /* TRACE */ if ((dct_diff & (1<<(size-1)))==0) dct_diff-= (1<<size) - 1; }#ifdef TRACE/* if (Trace_Flag) printf("): %d\n",dct_diff);*/#endif /* TRACE */ return dct_diff;}?? 快捷鍵說明
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