145 lines
2.7 KiB
C++
145 lines
2.7 KiB
C++
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#include "Decoder.h"
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#include "indices.h"
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#include "vlc_table.h"
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static unsigned char zig_zag_scan[64]={
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0,1,8,16,9,2,3,10,17,24,32,25,18,11,4,5,
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12,19,26,33,40,48,41,34,27,20,13,6,7,14,21,28,
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35,42,49,56,57,50,43,36,29,22,15,23,30,37,44,51,
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58,59,52,45,38,31,39,46,53,60,61,54,47,55,62,63
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};
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#define ESCAPE 7167
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// mode 1 = Inter (or Intra in advanced intra coding mode)
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// mode 0 = Intra
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void Decoder::getblock(int comp, int mode)
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{
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int val, i, j, sign;
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unsigned int code;
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VLCtab *tab;
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short *bp;
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int run, last, level, QP;
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short *qval;
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/* TODO: benski>
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i think this whole function can get replaced with
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ippiDecodeCoeffsIntra_H263_1u16s (mode==0)
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or
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ippiDecodeCoeffsInter_H263_1u16s (mode == 1)
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with pCoef = bp
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modQuantFlag = escapemode>=1
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scan = IPPVC_SCAN_ZIGZAG
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*/
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bp = block[comp];
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/* decode AC coefficients (or all coefficients in advanced intra coding
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* mode) */
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for (i = (mode == 0);; i++)
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{
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code = buffer.showbits(12);
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if (code >= 512)
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tab = &DCT3Dtab0[(code >> 5) - 16];
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else if (code >= 128)
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tab = &DCT3Dtab1[(code >> 2) - 32];
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else if (code >= 8)
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tab = &DCT3Dtab2[(code >> 0) - 8];
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else
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{
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fault = 1;
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return;
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}
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run = (tab->val >> 4) & 255;
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level = tab->val & 15;
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last = (tab->val >> 12) & 1;
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buffer.flushbits(tab->len);
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if (tab->val == ESCAPE)
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{
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/* escape */
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if (escapemode >= 1)
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{
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int is11 = buffer.getbits1();
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sign=0;
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last = buffer.getbits1();
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i+=run = buffer.getbits(6);
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if (is11)
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{
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level = buffer.getbits(11);
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if ((sign = (level>=1024)))
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val = 2048 - level;
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else
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val = level;
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}
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else
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{
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level = buffer.getbits(7);
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if ((sign = (level>=64)))
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val = 128 - level;
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else
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val = level;
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}
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}
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else
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{
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last = buffer.getbits1();
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i += run = buffer.getbits(6);
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level = buffer.getbits(8);
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if ((sign = (level >= 128)))
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val = 256 - level;
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else
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val = level;
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}
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}
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else
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{
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i += run;
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val = level;
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sign = buffer.getbits(1);
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}
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if (i >= 64)
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{
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fault = 1;
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return;
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}
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/* Descan in the proper order in advanced intra coding mode */
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j = zig_zag_scan[i];
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qval = &bp[j];
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QP = quant;
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/* TODO: benski>
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ippiQuantInvIntra_H263_16s_C1I
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or
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ippiQuantInvInter_H263_16s_C1I (mode == 1)
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but outside the loop
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pSrcDst = bp
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QP = quant
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modQuantFlag = escapemode >= 1
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*/
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/* TMN3 dequantization */
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if ((QP % 2) == 1)
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*qval = (sign ? -(QP * (2 * val + 1)) : QP * (2 * val + 1));
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else
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*qval = (sign ? -(QP * (2 * val + 1) - 1) : QP * (2 * val + 1) - 1);
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if (last)
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{
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/* That's it */
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return;
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}
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}}
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