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  1. /*
  2.  * This file is part of FFmpeg.
  3.  *
  4.  * FFmpeg is free software; you can redistribute it and/or
  5.  * modify it under the terms of the GNU Lesser General Public
  6.  * License as published by the Free Software Foundation; either
  7.  * version 2.1 of the License, or (at your option) any later version.
  8.  *
  9.  * FFmpeg is distributed in the hope that it will be useful,
  10.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12.  * Lesser General Public License for more details.
  13.  *
  14.  * You should have received a copy of the GNU Lesser General Public
  15.  * License along with FFmpeg; if not, write to the Free Software
  16.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17.  */
  18.  
  19. /**
  20.  * @file
  21.  * @brief IntraX8 (J-Frame) subdecoder, used by WMV2 and VC-1
  22.  */
  23.  
  24. #include "libavutil/avassert.h"
  25. #include "avcodec.h"
  26. #include "error_resilience.h"
  27. #include "get_bits.h"
  28. #include "idctdsp.h"
  29. #include "mpegvideo.h"
  30. #include "msmpeg4data.h"
  31. #include "intrax8huf.h"
  32. #include "intrax8.h"
  33. #include "intrax8dsp.h"
  34.  
  35. #define MAX_TABLE_DEPTH(table_bits, max_bits) ((max_bits+table_bits-1)/table_bits)
  36.  
  37. #define DC_VLC_BITS 9
  38. #define AC_VLC_BITS 9
  39. #define OR_VLC_BITS 7
  40.  
  41. #define DC_VLC_MTD MAX_TABLE_DEPTH(DC_VLC_BITS, MAX_DC_VLC_BITS)
  42. #define AC_VLC_MTD MAX_TABLE_DEPTH(AC_VLC_BITS, MAX_AC_VLC_BITS)
  43. #define OR_VLC_MTD MAX_TABLE_DEPTH(OR_VLC_BITS, MAX_OR_VLC_BITS)
  44.  
  45. static VLC j_ac_vlc[2][2][8];  //[quant<13],[intra/inter],[select]
  46. static VLC j_dc_vlc[2][8];     //[quant], [select]
  47. static VLC j_orient_vlc[2][4]; //[quant], [select]
  48.  
  49. static av_cold void x8_vlc_init(void){
  50.     int i;
  51.     int offset = 0;
  52.     int sizeidx = 0;
  53.     static const uint16_t sizes[8*4 + 8*2 + 2 + 4] = {
  54.         576, 548, 582, 618, 546, 616, 560, 642,
  55.         584, 582, 704, 664, 512, 544, 656, 640,
  56.         512, 648, 582, 566, 532, 614, 596, 648,
  57.         586, 552, 584, 590, 544, 578, 584, 624,
  58.  
  59.         528, 528, 526, 528, 536, 528, 526, 544,
  60.         544, 512, 512, 528, 528, 544, 512, 544,
  61.  
  62.         128, 128, 128, 128, 128, 128};
  63.  
  64.     static VLC_TYPE table[28150][2];
  65.  
  66. #define  init_ac_vlc(dst,src) \
  67.     dst.table = &table[offset]; \
  68.     dst.table_allocated = sizes[sizeidx]; \
  69.     offset += sizes[sizeidx++]; \
  70.        init_vlc(&dst, \
  71.               AC_VLC_BITS,77, \
  72.               &src[1],4,2, \
  73.               &src[0],4,2, \
  74.               INIT_VLC_USE_NEW_STATIC)
  75. //set ac tables
  76.     for(i=0;i<8;i++){
  77.         init_ac_vlc( j_ac_vlc[0][0][i], x8_ac0_highquant_table[i][0] );
  78.         init_ac_vlc( j_ac_vlc[0][1][i], x8_ac1_highquant_table[i][0] );
  79.         init_ac_vlc( j_ac_vlc[1][0][i], x8_ac0_lowquant_table [i][0] );
  80.         init_ac_vlc( j_ac_vlc[1][1][i], x8_ac1_lowquant_table [i][0] );
  81.     }
  82. #undef init_ac_vlc
  83.  
  84. //set dc tables
  85. #define init_dc_vlc(dst,src) \
  86.     dst.table = &table[offset]; \
  87.     dst.table_allocated = sizes[sizeidx]; \
  88.     offset += sizes[sizeidx++]; \
  89.         init_vlc(&dst, \
  90.         DC_VLC_BITS,34, \
  91.         &src[1],4,2, \
  92.         &src[0],4,2, \
  93.         INIT_VLC_USE_NEW_STATIC);
  94.     for(i=0;i<8;i++){
  95.         init_dc_vlc( j_dc_vlc[0][i], x8_dc_highquant_table[i][0]);
  96.         init_dc_vlc( j_dc_vlc[1][i], x8_dc_lowquant_table [i][0]);
  97.     }
  98. #undef init_dc_vlc
  99.  
  100. //set orient tables
  101. #define init_or_vlc(dst,src) \
  102.     dst.table = &table[offset]; \
  103.     dst.table_allocated = sizes[sizeidx]; \
  104.     offset += sizes[sizeidx++]; \
  105.     init_vlc(&dst, \
  106.     OR_VLC_BITS,12, \
  107.     &src[1],4,2, \
  108.     &src[0],4,2, \
  109.     INIT_VLC_USE_NEW_STATIC);
  110.     for(i=0;i<2;i++){
  111.         init_or_vlc( j_orient_vlc[0][i], x8_orient_highquant_table[i][0]);
  112.     }
  113.     for(i=0;i<4;i++){
  114.         init_or_vlc( j_orient_vlc[1][i], x8_orient_lowquant_table [i][0])
  115.     }
  116.     if (offset != sizeof(table)/sizeof(VLC_TYPE)/2)
  117.         av_log(NULL, AV_LOG_ERROR, "table size %i does not match needed %i\n", (int)(sizeof(table)/sizeof(VLC_TYPE)/2), offset);
  118. }
  119. #undef init_or_vlc
  120.  
  121. static void x8_reset_vlc_tables(IntraX8Context * w){
  122.     memset(w->j_dc_vlc,0,sizeof(w->j_dc_vlc));
  123.     memset(w->j_ac_vlc,0,sizeof(w->j_ac_vlc));
  124.     w->j_orient_vlc=NULL;
  125. }
  126.  
  127. static inline void x8_select_ac_table(IntraX8Context * const w , int mode){
  128.     MpegEncContext * const s= w->s;
  129.     int table_index;
  130.  
  131.     av_assert2(mode<4);
  132.  
  133.     if( w->j_ac_vlc[mode] ) return;
  134.  
  135.     table_index = get_bits(&s->gb, 3);
  136.     w->j_ac_vlc[mode] = &j_ac_vlc[w->quant<13][mode>>1][table_index];//2 modes use same tables
  137.     av_assert2(w->j_ac_vlc[mode]);
  138. }
  139.  
  140. static inline int x8_get_orient_vlc(IntraX8Context * w){
  141.     MpegEncContext * const s= w->s;
  142.     int table_index;
  143.  
  144.     if(!w->j_orient_vlc ){
  145.         table_index = get_bits(&s->gb, 1+(w->quant<13) );
  146.         w->j_orient_vlc = &j_orient_vlc[w->quant<13][table_index];
  147.     }
  148.  
  149.     return get_vlc2(&s->gb, w->j_orient_vlc->table, OR_VLC_BITS, OR_VLC_MTD);
  150. }
  151.  
  152. #define extra_bits(eb) (eb)
  153. #define extra_run   (0xFF<<8)
  154. #define extra_level (0x00<<8)
  155. #define   run_offset(r)    ((r)<<16)
  156. #define level_offset(l)    ((l)<<24)
  157. static const uint32_t ac_decode_table[]={
  158.     /*46*/ extra_bits(3) |  extra_run  | run_offset(16) | level_offset( 0),
  159.     /*47*/ extra_bits(3) |  extra_run  | run_offset(24) | level_offset( 0),
  160.     /*48*/ extra_bits(2) |  extra_run  | run_offset( 4) | level_offset( 1),
  161.     /*49*/ extra_bits(3) |  extra_run  | run_offset( 8) | level_offset( 1),
  162.  
  163.     /*50*/ extra_bits(5) |  extra_run  | run_offset(32) | level_offset( 0),
  164.     /*51*/ extra_bits(4) |  extra_run  | run_offset(16) | level_offset( 1),
  165.  
  166.     /*52*/ extra_bits(2) | extra_level | run_offset( 0) | level_offset( 4),
  167.     /*53*/ extra_bits(2) | extra_level | run_offset( 0) | level_offset( 8),
  168.     /*54*/ extra_bits(2) | extra_level | run_offset( 0) | level_offset(12),
  169.     /*55*/ extra_bits(3) | extra_level | run_offset( 0) | level_offset(16),
  170.     /*56*/ extra_bits(3) | extra_level | run_offset( 0) | level_offset(24),
  171.  
  172.     /*57*/ extra_bits(2) | extra_level | run_offset( 1) | level_offset( 3),
  173.     /*58*/ extra_bits(3) | extra_level | run_offset( 1) | level_offset( 7),
  174.  
  175.     /*59*/ extra_bits(2) |  extra_run  | run_offset(16) | level_offset( 0),
  176.     /*60*/ extra_bits(2) |  extra_run  | run_offset(20) | level_offset( 0),
  177.     /*61*/ extra_bits(2) |  extra_run  | run_offset(24) | level_offset( 0),
  178.     /*62*/ extra_bits(2) |  extra_run  | run_offset(28) | level_offset( 0),
  179.     /*63*/ extra_bits(4) |  extra_run  | run_offset(32) | level_offset( 0),
  180.     /*64*/ extra_bits(4) |  extra_run  | run_offset(48) | level_offset( 0),
  181.  
  182.     /*65*/ extra_bits(2) |  extra_run  | run_offset( 4) | level_offset( 1),
  183.     /*66*/ extra_bits(3) |  extra_run  | run_offset( 8) | level_offset( 1),
  184.     /*67*/ extra_bits(4) |  extra_run  | run_offset(16) | level_offset( 1),
  185.  
  186.     /*68*/ extra_bits(2) | extra_level | run_offset( 0) | level_offset( 4),
  187.     /*69*/ extra_bits(3) | extra_level | run_offset( 0) | level_offset( 8),
  188.     /*70*/ extra_bits(4) | extra_level | run_offset( 0) | level_offset(16),
  189.  
  190.     /*71*/ extra_bits(2) | extra_level | run_offset( 1) | level_offset( 3),
  191.     /*72*/ extra_bits(3) | extra_level | run_offset( 1) | level_offset( 7),
  192. };
  193. //extra_bits = 3bits; extra_run/level = 1 bit; run_offset = 6bits; level_offset = 5 bits;
  194. #undef extra_bits
  195. #undef extra_run
  196. #undef extra_level
  197. #undef run_offset
  198. #undef level_offset
  199.  
  200. static void x8_get_ac_rlf(IntraX8Context * const w, const int mode,
  201.                      int * const run, int * const level, int * const final){
  202.     MpegEncContext *  const s= w->s;
  203.     int i,e;
  204.  
  205. //    x8_select_ac_table(w,mode);
  206.     i = get_vlc2(&s->gb, w->j_ac_vlc[mode]->table, AC_VLC_BITS, AC_VLC_MTD);
  207.  
  208.     if(i<46){ //[0-45]
  209.         int t,l;
  210.         if(i<0){
  211.             (*level)=(*final)=//prevent 'may be used unilitialized'
  212.             (*run)=64;//this would cause error exit in the ac loop
  213.             return;
  214.         }
  215.  
  216.         (*final) = t = (i>22);
  217.         i-=23*t;
  218. /*
  219.   i== 0-15 r=0-15 l=0 ;r=i& %01111
  220.   i==16-19 r=0-3  l=1 ;r=i& %00011
  221.   i==20-21 r=0-1  l=2 ;r=i& %00001
  222.   i==22    r=0    l=3 ;r=i& %00000
  223. l=lut_l[i/2]={0,0,0,0,0,0,0,0,1,1,2,3}[i>>1];// 11 10'01 01'00 00'00 00'00 00'00 00 => 0xE50000
  224. t=lut_mask[l]={0x0f,0x03,0x01,0x00}[l]; as i<256 the higher bits do not matter */
  225.         l=(0xE50000>>(i&(0x1E)))&3;/*0x1E or (~1) or ((i>>1)<<1)*/
  226.         t=(0x01030F>>(l<<3));
  227.  
  228.         (*run)   = i&t;
  229.         (*level) = l;
  230.     }else if(i<73){//[46-72]
  231.         uint32_t sm;
  232.         uint32_t mask;
  233.  
  234.         i-=46;
  235.         sm=ac_decode_table[i];
  236.  
  237.         e=get_bits(&s->gb,sm&0xF);sm>>=8;//3bits
  238.         mask=sm&0xff;sm>>=8;             //1bit
  239.  
  240.         (*run)  =(sm&0xff) + (e&( mask));//6bits
  241.         (*level)=(sm>>8)   + (e&(~mask));//5bits
  242.         (*final)=i>(58-46);
  243.     }else if(i<75){//[73-74]
  244.         static const uint8_t crazy_mix_runlevel[32]={
  245.         0x22,0x32,0x33,0x53,0x23,0x42,0x43,0x63,
  246.         0x24,0x52,0x34,0x73,0x25,0x62,0x44,0x83,
  247.         0x26,0x72,0x35,0x54,0x27,0x82,0x45,0x64,
  248.         0x28,0x92,0x36,0x74,0x29,0xa2,0x46,0x84};
  249.  
  250.         (*final)=!(i&1);
  251.         e=get_bits(&s->gb,5);//get the extra bits
  252.         (*run)  =crazy_mix_runlevel[e]>>4;
  253.         (*level)=crazy_mix_runlevel[e]&0x0F;
  254.     }else{
  255.         (*level)=get_bits( &s->gb, 7-3*(i&1));
  256.         (*run)  =get_bits( &s->gb, 6);
  257.         (*final)=get_bits1(&s->gb);
  258.     }
  259.     return;
  260. }
  261.  
  262. //static const uint8_t dc_extra_sbits[]   ={0, 1,1, 1,1, 2,2, 3,3,   4,4,   5,5,   6,6,    7,7    };
  263. static const uint8_t dc_index_offset[]  ={ 0, 1,2, 3,4, 5,7, 9,13, 17,25, 33,49, 65,97, 129,193};
  264.  
  265. static int x8_get_dc_rlf(IntraX8Context * const w,int const mode, int * const level, int * const final){
  266.     MpegEncContext * const s= w->s;
  267.     int i,e,c;
  268.  
  269.     av_assert2(mode<3);
  270.     if( !w->j_dc_vlc[mode] ) {
  271.         int table_index;
  272.         table_index = get_bits(&s->gb, 3);
  273.         //4 modes, same table
  274.         w->j_dc_vlc[mode]= &j_dc_vlc[w->quant<13][table_index];
  275.     }
  276.  
  277.     i=get_vlc2(&s->gb, w->j_dc_vlc[mode]->table, DC_VLC_BITS, DC_VLC_MTD);
  278.  
  279.     /*(i>=17) {i-=17;final=1;}*/
  280.     c= i>16;
  281.     (*final)=c;
  282.     i-=17*c;
  283.  
  284.     if(i<=0){
  285.         (*level)=0;
  286.         return -i;
  287.     }
  288.     c=(i+1)>>1;//hackish way to calculate dc_extra_sbits[]
  289.     c-=c>1;
  290.  
  291.     e=get_bits(&s->gb,c);//get the extra bits
  292.     i=dc_index_offset[i]+(e>>1);
  293.  
  294.     e= -(e & 1);//0,0xffffff
  295.     (*level)= (i ^ e) - e;// (i^0)-0 , (i^0xff)-(-1)
  296.     return 0;
  297. }
  298. //end of huffman
  299.  
  300. static int x8_setup_spatial_predictor(IntraX8Context * const w, const int chroma){
  301.     MpegEncContext * const s= w->s;
  302.     int range;
  303.     int sum;
  304.     int quant;
  305.  
  306.     w->dsp.setup_spatial_compensation(s->dest[chroma], s->sc.edge_emu_buffer,
  307.                                       s->current_picture.f->linesize[chroma>0],
  308.                                       &range, &sum, w->edges);
  309.     if(chroma){
  310.         w->orient=w->chroma_orient;
  311.         quant=w->quant_dc_chroma;
  312.     }else{
  313.         quant=w->quant;
  314.     }
  315.  
  316.     w->flat_dc=0;
  317.     if(range < quant || range < 3){
  318.         w->orient=0;
  319.         if(range < 3){//yep you read right, a +-1 idct error may break decoding!
  320.             w->flat_dc=1;
  321.             sum+=9;
  322.             w->predicted_dc = (sum*6899)>>17;//((1<<17)+9)/(8+8+1+2)=6899
  323.         }
  324.     }
  325.     if(chroma)
  326.         return 0;
  327.  
  328.     av_assert2(w->orient < 3);
  329.     if(range < 2*w->quant){
  330.         if( (w->edges&3) == 0){
  331.             if(w->orient==1) w->orient=11;
  332.             if(w->orient==2) w->orient=10;
  333.         }else{
  334.             w->orient=0;
  335.         }
  336.         w->raw_orient=0;
  337.     }else{
  338.         static const uint8_t prediction_table[3][12]={
  339.             {0,8,4, 10,11, 2,6,9,1,3,5,7},
  340.             {4,0,8, 11,10, 3,5,2,6,9,1,7},
  341.             {8,0,4, 10,11, 1,7,2,6,9,3,5}
  342.         };
  343.         w->raw_orient=x8_get_orient_vlc(w);
  344.         if(w->raw_orient<0) return -1;
  345.         av_assert2(w->raw_orient < 12 );
  346.         av_assert2(w->orient<3);
  347.         w->orient=prediction_table[w->orient][w->raw_orient];
  348.     }
  349.     return 0;
  350. }
  351.  
  352. static void x8_update_predictions(IntraX8Context * const w, const int orient, const int est_run ){
  353.     MpegEncContext * const s= w->s;
  354.  
  355.     w->prediction_table[s->mb_x*2+(s->mb_y&1)] = (est_run<<2) + 1*(orient==4) + 2*(orient==8);
  356. /*
  357.   y=2n+0 ->//0 2 4
  358.   y=2n+1 ->//1 3 5
  359. */
  360. }
  361. static void x8_get_prediction_chroma(IntraX8Context * const w){
  362.     MpegEncContext * const s= w->s;
  363.  
  364.     w->edges = 1*( !(s->mb_x>>1) );
  365.     w->edges|= 2*( !(s->mb_y>>1) );
  366.     w->edges|= 4*( s->mb_x >= (2*s->mb_width-1) );//mb_x for chroma would always be odd
  367.  
  368.     w->raw_orient=0;
  369.     if(w->edges&3){//lut_co[8]={inv,4,8,8, inv,4,8,8}<- =>{1,1,0,0;1,1,0,0} => 0xCC
  370.         w->chroma_orient=4<<((0xCC>>w->edges)&1);
  371.         return;
  372.     }
  373.     w->chroma_orient = (w->prediction_table[2*s->mb_x-2] & 0x03)<<2;//block[x-1][y|1-1)]
  374. }
  375.  
  376. static void x8_get_prediction(IntraX8Context * const w){
  377.     MpegEncContext * const s= w->s;
  378.     int a,b,c,i;
  379.  
  380.     w->edges = 1*( !s->mb_x );
  381.     w->edges|= 2*( !s->mb_y );
  382.     w->edges|= 4*( s->mb_x >= (2*s->mb_width-1) );
  383.  
  384.     switch(w->edges&3){
  385.         case 0:
  386.             break;
  387.         case 1:
  388.             //take the one from the above block[0][y-1]
  389.             w->est_run = w->prediction_table[!(s->mb_y&1)]>>2;
  390.             w->orient  = 1;
  391.             return;
  392.         case 2:
  393.             //take the one from the previous block[x-1][0]
  394.             w->est_run = w->prediction_table[2*s->mb_x-2]>>2;
  395.             w->orient  = 2;
  396.             return;
  397.         case 3:
  398.             w->est_run = 16;
  399.             w->orient  = 0;
  400.             return;
  401.     }
  402.     //no edge cases
  403.     b= w->prediction_table[2*s->mb_x   + !(s->mb_y&1) ];//block[x  ][y-1]
  404.     a= w->prediction_table[2*s->mb_x-2 +  (s->mb_y&1) ];//block[x-1][y  ]
  405.     c= w->prediction_table[2*s->mb_x-2 + !(s->mb_y&1) ];//block[x-1][y-1]
  406.  
  407.     w->est_run = FFMIN(b,a);
  408.     /* This condition has nothing to do with w->edges, even if it looks
  409.        similar it would trigger if e.g. x=3;y=2;
  410.        I guess somebody wrote something wrong and it became standard. */
  411.     if( (s->mb_x & s->mb_y) != 0 ) w->est_run=FFMIN(c,w->est_run);
  412.     w->est_run>>=2;
  413.  
  414.     a&=3;
  415.     b&=3;
  416.     c&=3;
  417.  
  418.     i=( 0xFFEAF4C4>>(2*b+8*a) )&3;
  419.     if(i!=3) w->orient=i;
  420.     else     w->orient=( 0xFFEAD8>>(2*c+8*(w->quant>12)) )&3;
  421. /*
  422. lut1[b][a]={
  423. ->{0, 1, 0, pad},
  424.   {0, 1, X, pad},
  425.   {2, 2, 2, pad}}
  426.    pad 2   2  2; pad X  1  0; pad 0  1  0 <-
  427. -> 11 10 '10 10 '11 11'01 00 '11 00'01 00=>0xEAF4C4
  428.  
  429. lut2[q>12][c]={
  430.   ->{0,2,1,pad},
  431.     {2,2,2,pad}}
  432.    pad 2  2  2; pad 1  2  0 <-
  433. -> 11 10'10 10 '11 01'10 00=>0xEAD8
  434. */
  435. }
  436.  
  437.  
  438. static void x8_ac_compensation(IntraX8Context * const w, int const direction, int const dc_level){
  439.     MpegEncContext * const s= w->s;
  440.     int t;
  441. #define B(x,y)  s->block[0][w->idct_permutation[(x)+(y)*8]]
  442. #define T(x)  ((x) * dc_level + 0x8000) >> 16;
  443.     switch(direction){
  444.     case 0:
  445.         t = T(3811);//h
  446.         B(1,0) -= t;
  447.         B(0,1) -= t;
  448.  
  449.         t = T(487);//e
  450.         B(2,0) -= t;
  451.         B(0,2) -= t;
  452.  
  453.         t = T(506);//f
  454.         B(3,0) -= t;
  455.         B(0,3) -= t;
  456.  
  457.         t = T(135);//c
  458.         B(4,0) -= t;
  459.         B(0,4) -= t;
  460.         B(2,1) += t;
  461.         B(1,2) += t;
  462.         B(3,1) += t;
  463.         B(1,3) += t;
  464.  
  465.         t = T(173);//d
  466.         B(5,0) -= t;
  467.         B(0,5) -= t;
  468.  
  469.         t = T(61);//b
  470.         B(6,0) -= t;
  471.         B(0,6) -= t;
  472.         B(5,1) += t;
  473.         B(1,5) += t;
  474.  
  475.         t = T(42); //a
  476.         B(7,0) -= t;
  477.         B(0,7) -= t;
  478.         B(4,1) += t;
  479.         B(1,4) += t;
  480.         B(4,4) += t;
  481.  
  482.         t = T(1084);//g
  483.         B(1,1) += t;
  484.  
  485.         s->block_last_index[0] = FFMAX(s->block_last_index[0], 7*8);
  486.         break;
  487.     case 1:
  488.         B(0,1) -= T(6269);
  489.         B(0,3) -= T( 708);
  490.         B(0,5) -= T( 172);
  491.         B(0,7) -= T(  73);
  492.  
  493.         s->block_last_index[0] = FFMAX(s->block_last_index[0], 7*8);
  494.         break;
  495.     case 2:
  496.         B(1,0) -= T(6269);
  497.         B(3,0) -= T( 708);
  498.         B(5,0) -= T( 172);
  499.         B(7,0) -= T(  73);
  500.  
  501.         s->block_last_index[0] = FFMAX(s->block_last_index[0], 7);
  502.         break;
  503.     }
  504. #undef B
  505. #undef T
  506. }
  507.  
  508. static void dsp_x8_put_solidcolor(uint8_t const pix, uint8_t * dst, int const linesize){
  509.     int k;
  510.     for(k=0;k<8;k++){
  511.         memset(dst,pix,8);
  512.         dst+=linesize;
  513.     }
  514. }
  515.  
  516. static const int16_t quant_table[64] = {
  517.     256, 256, 256, 256,  256, 256, 259, 262,
  518.     265, 269, 272, 275,  278, 282, 285, 288,
  519.     292, 295, 299, 303,  306, 310, 314, 317,
  520.     321, 325, 329, 333,  337, 341, 345, 349,
  521.     353, 358, 362, 366,  371, 375, 379, 384,
  522.     389, 393, 398, 403,  408, 413, 417, 422,
  523.     428, 433, 438, 443,  448, 454, 459, 465,
  524.     470, 476, 482, 488,  493, 499, 505, 511
  525. };
  526.  
  527. static int x8_decode_intra_mb(IntraX8Context* const w, const int chroma){
  528.     MpegEncContext * const s= w->s;
  529.  
  530.     uint8_t * scantable;
  531.     int final,run,level;
  532.     int ac_mode,dc_mode,est_run,dc_level;
  533.     int pos,n;
  534.     int zeros_only;
  535.     int use_quant_matrix;
  536.     int sign;
  537.  
  538.     av_assert2(w->orient<12);
  539.     s->bdsp.clear_block(s->block[0]);
  540.  
  541.     if(chroma){
  542.         dc_mode=2;
  543.     }else{
  544.         dc_mode=!!w->est_run;//0,1
  545.     }
  546.  
  547.     if(x8_get_dc_rlf(w, dc_mode, &dc_level, &final)) return -1;
  548.     n=0;
  549.     zeros_only=0;
  550.     if(!final){//decode ac
  551.         use_quant_matrix=w->use_quant_matrix;
  552.         if(chroma){
  553.             ac_mode = 1;
  554.             est_run = 64;//not used
  555.         }else{
  556.             if (w->raw_orient < 3){
  557.                 use_quant_matrix = 0;
  558.             }
  559.             if(w->raw_orient > 4){
  560.                 ac_mode = 0;
  561.                 est_run = 64;
  562.             }else{
  563.                 if(w->est_run > 1){
  564.                     ac_mode = 2;
  565.                     est_run=w->est_run;
  566.                 }else{
  567.                     ac_mode = 3;
  568.                     est_run = 64;
  569.                 }
  570.             }
  571.         }
  572.         x8_select_ac_table(w,ac_mode);
  573.         /*scantable_selector[12]={0,2,0,1,1,1,0,2,2,0,1,2};<-
  574.         -> 10'01' 00'10' 10'00' 01'01' 01'00' 10'00 =>0x928548 */
  575.         scantable = w->scantable[ (0x928548>>(2*w->orient))&3 ].permutated;
  576.         pos=0;
  577.         do {
  578.             n++;
  579.             if( n >= est_run ){
  580.                 ac_mode=3;
  581.                 x8_select_ac_table(w,3);
  582.             }
  583.  
  584.             x8_get_ac_rlf(w,ac_mode,&run,&level,&final);
  585.  
  586.             pos+=run+1;
  587.             if(pos>63){
  588.                 //this also handles vlc error in x8_get_ac_rlf
  589.                 return -1;
  590.             }
  591.             level= (level+1) * w->dquant;
  592.             level+= w->qsum;
  593.  
  594.             sign = - get_bits1(&s->gb);
  595.             level = (level ^ sign) - sign;
  596.  
  597.             if(use_quant_matrix){
  598.                 level = (level*quant_table[pos])>>8;
  599.             }
  600.             s->block[0][ scantable[pos] ]=level;
  601.         }while(!final);
  602.  
  603.         s->block_last_index[0]=pos;
  604.     }else{//DC only
  605.         s->block_last_index[0]=0;
  606.         if(w->flat_dc && ((unsigned)(dc_level+1)) < 3){//[-1;1]
  607.             int32_t divide_quant= !chroma ? w->divide_quant_dc_luma:
  608.                                             w->divide_quant_dc_chroma;
  609.             int32_t dc_quant    = !chroma ? w->quant:
  610.                                             w->quant_dc_chroma;
  611.  
  612.             //original intent dc_level+=predicted_dc/quant; but it got lost somewhere in the rounding
  613.             dc_level+= (w->predicted_dc*divide_quant + (1<<12) )>>13;
  614.  
  615.             dsp_x8_put_solidcolor( av_clip_uint8((dc_level*dc_quant+4)>>3),
  616.                                    s->dest[chroma], s->current_picture.f->linesize[!!chroma]);
  617.  
  618.             goto block_placed;
  619.         }
  620.         zeros_only = (dc_level == 0);
  621.     }
  622.     if(!chroma){
  623.         s->block[0][0] = dc_level*w->quant;
  624.     }else{
  625.         s->block[0][0] = dc_level*w->quant_dc_chroma;
  626.     }
  627.  
  628.     //there is !zero_only check in the original, but dc_level check is enough
  629.     if( (unsigned int)(dc_level+1) >= 3 && (w->edges&3) != 3 ){
  630.         int direction;
  631.         /*ac_comp_direction[orient] = { 0, 3, 3, 1, 1, 0, 0, 0, 2, 2, 2, 1 };<-
  632.         -> 01'10' 10'10' 00'00' 00'01' 01'11' 11'00 =>0x6A017C */
  633.         direction= (0x6A017C>>(w->orient*2))&3;
  634.         if (direction != 3){
  635.             x8_ac_compensation(w, direction, s->block[0][0]);//modify block_last[]
  636.         }
  637.     }
  638.  
  639.     if(w->flat_dc){
  640.         dsp_x8_put_solidcolor(w->predicted_dc, s->dest[chroma], s->current_picture.f->linesize[!!chroma]);
  641.     }else{
  642.         w->dsp.spatial_compensation[w->orient]( s->sc.edge_emu_buffer,
  643.                                             s->dest[chroma],
  644.                                             s->current_picture.f->linesize[!!chroma] );
  645.     }
  646.     if(!zeros_only)
  647.         w->wdsp.idct_add(s->dest[chroma],
  648.                          s->current_picture.f->linesize[!!chroma],
  649.                          s->block[0]);
  650.  
  651. block_placed:
  652.  
  653.     if(!chroma){
  654.         x8_update_predictions(w,w->orient,n);
  655.     }
  656.  
  657.     if(s->loop_filter){
  658.         uint8_t* ptr = s->dest[chroma];
  659.         int linesize = s->current_picture.f->linesize[!!chroma];
  660.  
  661.         if(!( (w->edges&2) || ( zeros_only && (w->orient|4)==4 ) )){
  662.             w->dsp.h_loop_filter(ptr, linesize, w->quant);
  663.         }
  664.         if(!( (w->edges&1) || ( zeros_only && (w->orient|8)==8 ) )){
  665.             w->dsp.v_loop_filter(ptr, linesize, w->quant);
  666.         }
  667.     }
  668.     return 0;
  669. }
  670.  
  671. static void x8_init_block_index(MpegEncContext *s){ //FIXME maybe merge with ff_*
  672. //not s->linesize as this would be wrong for field pics
  673. //not that IntraX8 has interlacing support ;)
  674.     const int linesize   = s->current_picture.f->linesize[0];
  675.     const int uvlinesize = s->current_picture.f->linesize[1];
  676.  
  677.     s->dest[0] = s->current_picture.f->data[0];
  678.     s->dest[1] = s->current_picture.f->data[1];
  679.     s->dest[2] = s->current_picture.f->data[2];
  680.  
  681.     s->dest[0] +=   s->mb_y        *   linesize << 3;
  682.     s->dest[1] += ( s->mb_y&(~1) ) * uvlinesize << 2;//chroma blocks are on add rows
  683.     s->dest[2] += ( s->mb_y&(~1) ) * uvlinesize << 2;
  684. }
  685.  
  686. /**
  687.  * Initialize IntraX8 frame decoder.
  688.  * Requires valid MpegEncContext with valid s->mb_width before calling.
  689.  * @param w pointer to IntraX8Context
  690.  * @param s pointer to MpegEncContext of the parent codec
  691.  */
  692. av_cold void ff_intrax8_common_init(IntraX8Context * w, MpegEncContext * const s){
  693.  
  694.     w->s=s;
  695.     x8_vlc_init();
  696.     av_assert0(s->mb_width>0);
  697.     w->prediction_table=av_mallocz(s->mb_width*2*2);//two rows, 2 blocks per cannon mb
  698.  
  699.     ff_wmv2dsp_init(&w->wdsp);
  700.     ff_init_scantable_permutation(w->idct_permutation,
  701.                                   w->wdsp.idct_perm);
  702.  
  703.     ff_init_scantable(w->idct_permutation, &w->scantable[0], ff_wmv1_scantable[0]);
  704.     ff_init_scantable(w->idct_permutation, &w->scantable[1], ff_wmv1_scantable[2]);
  705.     ff_init_scantable(w->idct_permutation, &w->scantable[2], ff_wmv1_scantable[3]);
  706.  
  707.     ff_intrax8dsp_init(&w->dsp);
  708. }
  709.  
  710. /**
  711.  * Destroy IntraX8 frame structure.
  712.  * @param w pointer to IntraX8Context
  713.  */
  714. av_cold void ff_intrax8_common_end(IntraX8Context * w)
  715. {
  716.     av_freep(&w->prediction_table);
  717. }
  718.  
  719. /**
  720.  * Decode single IntraX8 frame.
  721.  * The parent codec must fill s->loopfilter and s->gb (bitstream).
  722.  * The parent codec must call ff_mpv_frame_start(), ff_er_frame_start() before calling this function.
  723.  * The parent codec must call ff_er_frame_end(), ff_mpv_frame_end() after calling this function.
  724.  * This function does not use ff_mpv_decode_mb().
  725.  * lowres decoding is theoretically impossible.
  726.  * @param w pointer to IntraX8Context
  727.  * @param dquant doubled quantizer, it would be odd in case of VC-1 halfpq==1.
  728.  * @param quant_offset offset away from zero
  729.  */
  730. int ff_intrax8_decode_picture(IntraX8Context * const w, int dquant, int quant_offset){
  731.     MpegEncContext * const s= w->s;
  732.     int mb_xy;
  733.     w->use_quant_matrix = get_bits1(&s->gb);
  734.  
  735.     w->dquant = dquant;
  736.     w->quant  = dquant >> 1;
  737.     w->qsum   = quant_offset;
  738.  
  739.     w->divide_quant_dc_luma = ((1<<16) + (w->quant>>1)) / w->quant;
  740.     if(w->quant < 5){
  741.         w->quant_dc_chroma =  w->quant;
  742.         w->divide_quant_dc_chroma = w->divide_quant_dc_luma;
  743.     }else{
  744.         w->quant_dc_chroma =  w->quant+((w->quant+3)>>3);
  745.         w->divide_quant_dc_chroma = ((1<<16) + (w->quant_dc_chroma>>1)) / w->quant_dc_chroma;
  746.     }
  747.     x8_reset_vlc_tables(w);
  748.  
  749.     s->resync_mb_x=0;
  750.     s->resync_mb_y=0;
  751.  
  752.     for(s->mb_y=0; s->mb_y < s->mb_height*2; s->mb_y++){
  753.         x8_init_block_index(s);
  754.         mb_xy=(s->mb_y>>1)*s->mb_stride;
  755.  
  756.         for(s->mb_x=0; s->mb_x < s->mb_width*2; s->mb_x++){
  757.             x8_get_prediction(w);
  758.             if(x8_setup_spatial_predictor(w,0)) goto error;
  759.             if(x8_decode_intra_mb(w,0)) goto error;
  760.  
  761.             if( s->mb_x & s->mb_y & 1 ){
  762.                 x8_get_prediction_chroma(w);
  763.  
  764.                 /*when setting up chroma, no vlc is read,
  765.                 so no error condition can be reached*/
  766.                 x8_setup_spatial_predictor(w,1);
  767.                 if(x8_decode_intra_mb(w,1)) goto error;
  768.  
  769.                 x8_setup_spatial_predictor(w,2);
  770.                 if(x8_decode_intra_mb(w,2)) goto error;
  771.  
  772.                 s->dest[1]+= 8;
  773.                 s->dest[2]+= 8;
  774.  
  775.                 /*emulate MB info in the relevant tables*/
  776.                 s->mbskip_table [mb_xy]=0;
  777.                 s->mbintra_table[mb_xy]=1;
  778.                 s->current_picture.qscale_table[mb_xy] = w->quant;
  779.                 mb_xy++;
  780.             }
  781.             s->dest[0]+= 8;
  782.         }
  783.         if(s->mb_y&1){
  784.             ff_mpeg_draw_horiz_band(s, (s->mb_y-1)*8, 16);
  785.         }
  786.     }
  787.  
  788. error:
  789.     ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y,
  790.                         (s->mb_x>>1)-1, (s->mb_y>>1)-1,
  791.                         ER_MB_END );
  792.     return 0;
  793. }
  794.