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FFmpeg/libavcodec/cavsdec.c

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  1. /*

  2.  * Chinese AVS video (AVS1-P2, JiZhun profile) decoder.

  3.  * Copyright (c) 2006  Stefan Gehrer <stefan.gehrer@gmx.de>

  4.  *

  5.  * This file is part of Libav.

  6.  *

  7.  * Libav is free software; you can redistribute it and/or

  8.  * modify it under the terms of the GNU Lesser General Public

  9.  * License as published by the Free Software Foundation; either

  10.  * version 2.1 of the License, or (at your option) any later version.

  11.  *

  12.  * Libav is distributed in the hope that it will be useful,

  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  15.  * Lesser General Public License for more details.

  16.  *

  17.  * You should have received a copy of the GNU Lesser General Public

  18.  * License along with Libav; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. /**

  23.  * @file

  24.  * Chinese AVS video (AVS1-P2, JiZhun profile) decoder

  25.  * @author Stefan Gehrer <stefan.gehrer@gmx.de>

  26.  */

  27. 

  28. #include "avcodec.h"

  29. #include "get_bits.h"

  30. #include "golomb.h"

  31. #include "cavs.h"

  32. 

  33. static const uint8_t mv_scan[4] = {

  34.     MV_FWD_X0,MV_FWD_X1,

  35.     MV_FWD_X2,MV_FWD_X3

  36. };

  37. 

  38. static const uint8_t cbp_tab[64][2] = {

  39.   {63, 0},{15,15},{31,63},{47,31},{ 0,16},{14,32},{13,47},{11,13},

  40.   { 7,14},{ 5,11},{10,12},{ 8, 5},{12,10},{61, 7},{ 4,48},{55, 3},

  41.   { 1, 2},{ 2, 8},{59, 4},{ 3, 1},{62,61},{ 9,55},{ 6,59},{29,62},

  42.   {45,29},{51,27},{23,23},{39,19},{27,30},{46,28},{53, 9},{30, 6},

  43.   {43,60},{37,21},{60,44},{16,26},{21,51},{28,35},{19,18},{35,20},

  44.   {42,24},{26,53},{44,17},{32,37},{58,39},{24,45},{20,58},{17,43},

  45.   {18,42},{48,46},{22,36},{33,33},{25,34},{49,40},{40,52},{36,49},

  46.   {34,50},{50,56},{52,25},{54,22},{41,54},{56,57},{38,41},{57,38}

  47. };

  48. 

  49. /*****************************************************************************

  50.  *

  51.  * motion vector prediction

  52.  *

  53.  ****************************************************************************/

  54. 

  55. static inline void store_mvs(AVSContext *h) {

  56.     h->col_mv[h->mbidx*4 + 0] = h->mv[MV_FWD_X0];

  57.     h->col_mv[h->mbidx*4 + 1] = h->mv[MV_FWD_X1];

  58.     h->col_mv[h->mbidx*4 + 2] = h->mv[MV_FWD_X2];

  59.     h->col_mv[h->mbidx*4 + 3] = h->mv[MV_FWD_X3];

  60. }

  61. 

  62. static inline void mv_pred_direct(AVSContext *h, cavs_vector *pmv_fw,

  63.                                   cavs_vector *col_mv) {

  64.     cavs_vector *pmv_bw = pmv_fw + MV_BWD_OFFS;

  65.     int den = h->direct_den[col_mv->ref];

  66.     int m = col_mv->x >> 31;

  67. 

  68.     pmv_fw->dist = h->dist[1];

  69.     pmv_bw->dist = h->dist[0];

  70.     pmv_fw->ref = 1;

  71.     pmv_bw->ref = 0;

  72.     /* scale the co-located motion vector according to its temporal span */

  73.     pmv_fw->x = (((den+(den*col_mv->x*pmv_fw->dist^m)-m-1)>>14)^m)-m;

  74.     pmv_bw->x = m-(((den+(den*col_mv->x*pmv_bw->dist^m)-m-1)>>14)^m);

  75.     m = col_mv->y >> 31;

  76.     pmv_fw->y = (((den+(den*col_mv->y*pmv_fw->dist^m)-m-1)>>14)^m)-m;

  77.     pmv_bw->y = m-(((den+(den*col_mv->y*pmv_bw->dist^m)-m-1)>>14)^m);

  78. }

  79. 

  80. static inline void mv_pred_sym(AVSContext *h, cavs_vector *src, enum cavs_block size) {

  81.     cavs_vector *dst = src + MV_BWD_OFFS;

  82. 

  83.     /* backward mv is the scaled and negated forward mv */

  84.     dst->x = -((src->x * h->sym_factor + 256) >> 9);

  85.     dst->y = -((src->y * h->sym_factor + 256) >> 9);

  86.     dst->ref = 0;

  87.     dst->dist = h->dist[0];

  88.     set_mvs(dst, size);

  89. }

  90. 

  91. /*****************************************************************************

  92.  *

  93.  * residual data decoding

  94.  *

  95.  ****************************************************************************/

  96. 

  97. /** kth-order exponential golomb code */

  98. static inline int get_ue_code(GetBitContext *gb, int order) {

  99.     if(order) {

  100.         int ret = get_ue_golomb(gb) << order;

  101.         return ret + get_bits(gb,order);

  102.     }

  103.     return get_ue_golomb(gb);

  104. }

  105. 

  106. /**

  107.  * decode coefficients from one 8x8 block, dequantize, inverse transform

  108.  *  and add them to sample block

  109.  * @param r pointer to 2D VLC table

  110.  * @param esc_golomb_order escape codes are k-golomb with this order k

  111.  * @param qp quantizer

  112.  * @param dst location of sample block

  113.  * @param stride line stride in frame buffer

  114.  */

  115. static int decode_residual_block(AVSContext *h, GetBitContext *gb,

  116.                                  const struct dec_2dvlc *r, int esc_golomb_order,

  117.                                  int qp, uint8_t *dst, int stride) {

  118.     int i, level_code, esc_code, level, run, mask;

  119.     DCTELEM level_buf[65];

  120.     uint8_t run_buf[65];

  121.     DCTELEM *block = h->block;

  122. 

  123.     for(i=0;i<65;i++) {

  124.         level_code = get_ue_code(gb,r->golomb_order);

  125.         if(level_code >= ESCAPE_CODE) {

  126.             run = ((level_code - ESCAPE_CODE) >> 1) + 1;

  127.             esc_code = get_ue_code(gb,esc_golomb_order);

  128.             level = esc_code + (run > r->max_run ? 1 : r->level_add[run]);

  129.             while(level > r->inc_limit)

  130.                 r++;

  131.             mask = -(level_code & 1);

  132.             level = (level^mask) - mask;

  133.         } else if (level_code >= 0) {

  134.             level = r->rltab[level_code][0];

  135.             if(!level) //end of block signal

  136.                 break;

  137.             run   = r->rltab[level_code][1];

  138.             r += r->rltab[level_code][2];

  139.         } else {

  140.             break;

  141.         }

  142.         level_buf[i] = level;

  143.         run_buf[i] = run;

  144.     }

  145.     if(dequant(h,level_buf, run_buf, block, ff_cavs_dequant_mul[qp],

  146.                ff_cavs_dequant_shift[qp], i))

  147.         return -1;

  148.     h->cdsp.cavs_idct8_add(dst,block,stride);

  149.     h->s.dsp.clear_block(block);

  150.     return 0;

  151. }

  152. 

  153. 

  154. static inline void decode_residual_chroma(AVSContext *h) {

  155.     if(h->cbp & (1<<4))

  156.         decode_residual_block(h,&h->s.gb,ff_cavs_chroma_dec,0,

  157.                               ff_cavs_chroma_qp[h->qp],h->cu,h->c_stride);

  158.     if(h->cbp & (1<<5))

  159.         decode_residual_block(h,&h->s.gb,ff_cavs_chroma_dec,0,

  160.                               ff_cavs_chroma_qp[h->qp],h->cv,h->c_stride);

  161. }

  162. 

  163. static inline int decode_residual_inter(AVSContext *h) {

  164.     int block;

  165. 

  166.     /* get coded block pattern */

  167.     int cbp= get_ue_golomb(&h->s.gb);

  168.     if(cbp > 63){

  169.         av_log(h->s.avctx, AV_LOG_ERROR, "illegal inter cbp\n");

  170.         return -1;

  171.     }

  172.     h->cbp = cbp_tab[cbp][1];

  173. 

  174.     /* get quantizer */

  175.     if(h->cbp && !h->qp_fixed)

  176.         h->qp = (h->qp + get_se_golomb(&h->s.gb)) & 63;

  177.     for(block=0;block<4;block++)

  178.         if(h->cbp & (1<<block))

  179.             decode_residual_block(h,&h->s.gb,ff_cavs_inter_dec,0,h->qp,

  180.                                   h->cy + h->luma_scan[block], h->l_stride);

  181.     decode_residual_chroma(h);

  182. 

  183.     return 0;

  184. }

  185. 

  186. /*****************************************************************************

  187.  *

  188.  * macroblock level

  189.  *

  190.  ****************************************************************************/

  191. 

  192. static int decode_mb_i(AVSContext *h, int cbp_code) {

  193.     GetBitContext *gb = &h->s.gb;

  194.     unsigned pred_mode_uv;

  195.     int block;

  196.     uint8_t top[18];

  197.     uint8_t *left = NULL;

  198.     uint8_t *d;

  199. 

  200.     ff_cavs_init_mb(h);

  201. 

  202.     /* get intra prediction modes from stream */

  203.     for(block=0;block<4;block++) {

  204.         int nA,nB,predpred;

  205.         int pos = ff_cavs_scan3x3[block];

  206. 

  207.         nA = h->pred_mode_Y[pos-1];

  208.         nB = h->pred_mode_Y[pos-3];

  209.         predpred = FFMIN(nA,nB);

  210.         if(predpred == NOT_AVAIL) // if either is not available

  211.             predpred = INTRA_L_LP;

  212.         if(!get_bits1(gb)){

  213.             int rem_mode= get_bits(gb, 2);

  214.             predpred = rem_mode + (rem_mode >= predpred);

  215.         }

  216.         h->pred_mode_Y[pos] = predpred;

  217.     }

  218.     pred_mode_uv = get_ue_golomb(gb);

  219.     if(pred_mode_uv > 6) {

  220.         av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra chroma pred mode\n");

  221.         return -1;

  222.     }

  223.     ff_cavs_modify_mb_i(h, &pred_mode_uv);

  224. 

  225.     /* get coded block pattern */

  226.     if(h->pic_type == AV_PICTURE_TYPE_I)

  227.         cbp_code = get_ue_golomb(gb);

  228.     if(cbp_code > 63){

  229.         av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra cbp\n");

  230.         return -1;

  231.     }

  232.     h->cbp = cbp_tab[cbp_code][0];

  233.     if(h->cbp && !h->qp_fixed)

  234.         h->qp = (h->qp + get_se_golomb(gb)) & 63; //qp_delta

  235. 

  236.     /* luma intra prediction interleaved with residual decode/transform/add */

  237.     for(block=0;block<4;block++) {

  238.         d = h->cy + h->luma_scan[block];

  239.         ff_cavs_load_intra_pred_luma(h, top, &left, block);

  240.         h->intra_pred_l[h->pred_mode_Y[ff_cavs_scan3x3[block]]]

  241.             (d, top, left, h->l_stride);

  242.         if(h->cbp & (1<<block))

  243.             decode_residual_block(h,gb,ff_cavs_intra_dec,1,h->qp,d,h->l_stride);

  244.     }

  245. 

  246.     /* chroma intra prediction */

  247.     ff_cavs_load_intra_pred_chroma(h);

  248.     h->intra_pred_c[pred_mode_uv](h->cu, &h->top_border_u[h->mbx*10],

  249.                                   h->left_border_u, h->c_stride);

  250.     h->intra_pred_c[pred_mode_uv](h->cv, &h->top_border_v[h->mbx*10],

  251.                                   h->left_border_v, h->c_stride);

  252. 

  253.     decode_residual_chroma(h);

  254.     ff_cavs_filter(h,I_8X8);

  255.     set_mv_intra(h);

  256.     return 0;

  257. }

  258. 

  259. static void decode_mb_p(AVSContext *h, enum cavs_mb mb_type) {

  260.     GetBitContext *gb = &h->s.gb;

  261.     int ref[4];

  262. 

  263.     ff_cavs_init_mb(h);

  264.     switch(mb_type) {

  265.     case P_SKIP:

  266.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_PSKIP,  BLK_16X16, 0);

  267.         break;

  268.     case P_16X16:

  269.         ref[0] = h->ref_flag ? 0 : get_bits1(gb);

  270.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16,ref[0]);

  271.         break;

  272.     case P_16X8:

  273.         ref[0] = h->ref_flag ? 0 : get_bits1(gb);

  274.         ref[2] = h->ref_flag ? 0 : get_bits1(gb);

  275.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_TOP,    BLK_16X8, ref[0]);

  276.         ff_cavs_mv(h, MV_FWD_X2, MV_FWD_A1, MV_PRED_LEFT,   BLK_16X8, ref[2]);

  277.         break;

  278.     case P_8X16:

  279.         ref[0] = h->ref_flag ? 0 : get_bits1(gb);

  280.         ref[1] = h->ref_flag ? 0 : get_bits1(gb);

  281.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_LEFT,   BLK_8X16, ref[0]);

  282.         ff_cavs_mv(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_TOPRIGHT,BLK_8X16, ref[1]);

  283.         break;

  284.     case P_8X8:

  285.         ref[0] = h->ref_flag ? 0 : get_bits1(gb);

  286.         ref[1] = h->ref_flag ? 0 : get_bits1(gb);

  287.         ref[2] = h->ref_flag ? 0 : get_bits1(gb);

  288.         ref[3] = h->ref_flag ? 0 : get_bits1(gb);

  289.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_MEDIAN,   BLK_8X8, ref[0]);

  290.         ff_cavs_mv(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_MEDIAN,   BLK_8X8, ref[1]);

  291.         ff_cavs_mv(h, MV_FWD_X2, MV_FWD_X1, MV_PRED_MEDIAN,   BLK_8X8, ref[2]);

  292.         ff_cavs_mv(h, MV_FWD_X3, MV_FWD_X0, MV_PRED_MEDIAN,   BLK_8X8, ref[3]);

  293.     }

  294.     ff_cavs_inter(h, mb_type);

  295.     set_intra_mode_default(h);

  296.     store_mvs(h);

  297.     if(mb_type != P_SKIP)

  298.         decode_residual_inter(h);

  299.     ff_cavs_filter(h,mb_type);

  300.     h->col_type_base[h->mbidx] = mb_type;

  301. }

  302. 

  303. static void decode_mb_b(AVSContext *h, enum cavs_mb mb_type) {

  304.     int block;

  305.     enum cavs_sub_mb sub_type[4];

  306.     int flags;

  307. 

  308.     ff_cavs_init_mb(h);

  309. 

  310.     /* reset all MVs */

  311.     h->mv[MV_FWD_X0] = ff_cavs_dir_mv;

  312.     set_mvs(&h->mv[MV_FWD_X0], BLK_16X16);

  313.     h->mv[MV_BWD_X0] = ff_cavs_dir_mv;

  314.     set_mvs(&h->mv[MV_BWD_X0], BLK_16X16);

  315.     switch(mb_type) {

  316.     case B_SKIP:

  317.     case B_DIRECT:

  318.         if(!h->col_type_base[h->mbidx]) {

  319.             /* intra MB at co-location, do in-plane prediction */

  320.             ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_BSKIP, BLK_16X16, 1);

  321.             ff_cavs_mv(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_BSKIP, BLK_16X16, 0);

  322.         } else

  323.             /* direct prediction from co-located P MB, block-wise */

  324.             for(block=0;block<4;block++)

  325.                 mv_pred_direct(h,&h->mv[mv_scan[block]],

  326.                                  &h->col_mv[h->mbidx*4 + block]);

  327.         break;

  328.     case B_FWD_16X16:

  329.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16, 1);

  330.         break;

  331.     case B_SYM_16X16:

  332.         ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16, 1);

  333.         mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_16X16);

  334.         break;

  335.     case B_BWD_16X16:

  336.         ff_cavs_mv(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_MEDIAN, BLK_16X16, 0);

  337.         break;

  338.     case B_8X8:

  339.         for(block=0;block<4;block++)

  340.             sub_type[block] = get_bits(&h->s.gb,2);

  341.         for(block=0;block<4;block++) {

  342.             switch(sub_type[block]) {

  343.             case B_SUB_DIRECT:

  344.                 if(!h->col_type_base[h->mbidx]) {

  345.                     /* intra MB at co-location, do in-plane prediction */

  346.                     ff_cavs_mv(h, mv_scan[block], mv_scan[block]-3,

  347.                             MV_PRED_BSKIP, BLK_8X8, 1);

  348.                     ff_cavs_mv(h, mv_scan[block]+MV_BWD_OFFS,

  349.                             mv_scan[block]-3+MV_BWD_OFFS,

  350.                             MV_PRED_BSKIP, BLK_8X8, 0);

  351.                 } else

  352.                     mv_pred_direct(h,&h->mv[mv_scan[block]],

  353.                                    &h->col_mv[h->mbidx*4 + block]);

  354.                 break;

  355.             case B_SUB_FWD:

  356.                 ff_cavs_mv(h, mv_scan[block], mv_scan[block]-3,

  357.                         MV_PRED_MEDIAN, BLK_8X8, 1);

  358.                 break;

  359.             case B_SUB_SYM:

  360.                 ff_cavs_mv(h, mv_scan[block], mv_scan[block]-3,

  361.                         MV_PRED_MEDIAN, BLK_8X8, 1);

  362.                 mv_pred_sym(h, &h->mv[mv_scan[block]], BLK_8X8);

  363.                 break;

  364.             }

  365.         }

  366.         for(block=0;block<4;block++) {

  367.             if(sub_type[block] == B_SUB_BWD)

  368.                 ff_cavs_mv(h, mv_scan[block]+MV_BWD_OFFS,

  369.                         mv_scan[block]+MV_BWD_OFFS-3,

  370.                         MV_PRED_MEDIAN, BLK_8X8, 0);

  371.         }

  372.         break;

  373.     default:

  374.         assert((mb_type > B_SYM_16X16) && (mb_type < B_8X8));

  375.         flags = ff_cavs_partition_flags[mb_type];

  376.         if(mb_type & 1) { /* 16x8 macroblock types */

  377.             if(flags & FWD0)

  378.                 ff_cavs_mv(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_TOP,  BLK_16X8, 1);

  379.             if(flags & SYM0)

  380.                 mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_16X8);

  381.             if(flags & FWD1)

  382.                 ff_cavs_mv(h, MV_FWD_X2, MV_FWD_A1, MV_PRED_LEFT, BLK_16X8, 1);

  383.             if(flags & SYM1)

  384.                 mv_pred_sym(h, &h->mv[MV_FWD_X2], BLK_16X8);

  385.             if(flags & BWD0)

  386.                 ff_cavs_mv(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_TOP,  BLK_16X8, 0);

  387.             if(flags & BWD1)

  388.                 ff_cavs_mv(h, MV_BWD_X2, MV_BWD_A1, MV_PRED_LEFT, BLK_16X8, 0);

  389.         } else {          /* 8x16 macroblock types */

  390.             if(flags & FWD0)

  391.                 ff_cavs_mv(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_LEFT, BLK_8X16, 1);

  392.             if(flags & SYM0)

  393.                 mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_8X16);

  394.             if(flags & FWD1)

  395.                 ff_cavs_mv(h,MV_FWD_X1,MV_FWD_C2,MV_PRED_TOPRIGHT,BLK_8X16,1);

  396.             if(flags & SYM1)

  397.                 mv_pred_sym(h, &h->mv[MV_FWD_X1], BLK_8X16);

  398.             if(flags & BWD0)

  399.                 ff_cavs_mv(h, MV_BWD_X0, MV_BWD_B3, MV_PRED_LEFT, BLK_8X16, 0);

  400.             if(flags & BWD1)

  401.                 ff_cavs_mv(h,MV_BWD_X1,MV_BWD_C2,MV_PRED_TOPRIGHT,BLK_8X16,0);

  402.         }

  403.     }

  404.     ff_cavs_inter(h, mb_type);

  405.     set_intra_mode_default(h);

  406.     if(mb_type != B_SKIP)

  407.         decode_residual_inter(h);

  408.     ff_cavs_filter(h,mb_type);

  409. }

  410. 

  411. /*****************************************************************************

  412.  *

  413.  * slice level

  414.  *

  415.  ****************************************************************************/

  416. 

  417. static inline int decode_slice_header(AVSContext *h, GetBitContext *gb) {

  418.     if(h->stc > 0xAF)

  419.         av_log(h->s.avctx, AV_LOG_ERROR, "unexpected start code 0x%02x\n", h->stc);

  420.     h->mby = h->stc;

  421.     h->mbidx = h->mby*h->mb_width;

  422. 

  423.     /* mark top macroblocks as unavailable */

  424.     h->flags &= ~(B_AVAIL|C_AVAIL);

  425.     if((h->mby == 0) && (!h->qp_fixed)){

  426.         h->qp_fixed = get_bits1(gb);

  427.         h->qp = get_bits(gb,6);

  428.     }

  429.     /* inter frame or second slice can have weighting params */

  430.     if((h->pic_type != AV_PICTURE_TYPE_I) || (!h->pic_structure && h->mby >= h->mb_width/2))

  431.         if(get_bits1(gb)) { //slice_weighting_flag

  432.             av_log(h->s.avctx, AV_LOG_ERROR,

  433.                    "weighted prediction not yet supported\n");

  434.         }

  435.     return 0;

  436. }

  437. 

  438. static inline int check_for_slice(AVSContext *h) {

  439.     GetBitContext *gb = &h->s.gb;

  440.     int align;

  441. 

  442.     if(h->mbx)

  443.         return 0;

  444.     align = (-get_bits_count(gb)) & 7;

  445.     /* check for stuffing byte */

  446.     if(!align && (show_bits(gb,8) == 0x80))

  447.         align = 8;

  448.     if((show_bits_long(gb,24+align) & 0xFFFFFF) == 0x000001) {

  449.         skip_bits_long(gb,24+align);

  450.         h->stc = get_bits(gb,8);

  451.         if (h->stc >= h->mb_height)

  452.             return 0;

  453.         decode_slice_header(h,gb);

  454.         return 1;

  455.     }

  456.     return 0;

  457. }

  458. 

  459. /*****************************************************************************

  460.  *

  461.  * frame level

  462.  *

  463.  ****************************************************************************/

  464. 

  465. static int decode_pic(AVSContext *h) {

  466.     MpegEncContext *s = &h->s;

  467.     int skip_count = -1;

  468.     enum cavs_mb mb_type;

  469. 

  470.     if (!s->context_initialized) {

  471.         s->avctx->idct_algo = FF_IDCT_CAVS;

  472.         if (ff_MPV_common_init(s) < 0)

  473.             return -1;

  474.         ff_init_scantable(s->dsp.idct_permutation,&h->scantable,ff_zigzag_direct);

  475.     }

  476.     skip_bits(&s->gb,16);//bbv_dwlay

  477.     if(h->stc == PIC_PB_START_CODE) {

  478.         h->pic_type = get_bits(&s->gb,2) + AV_PICTURE_TYPE_I;

  479.         if(h->pic_type > AV_PICTURE_TYPE_B) {

  480.             av_log(s->avctx, AV_LOG_ERROR, "illegal picture type\n");

  481.             return -1;

  482.         }

  483.         /* make sure we have the reference frames we need */

  484.         if(!h->DPB[0].f.data[0] ||

  485.           (!h->DPB[1].f.data[0] && h->pic_type == AV_PICTURE_TYPE_B))

  486.             return -1;

  487.     } else {

  488.         h->pic_type = AV_PICTURE_TYPE_I;

  489.         if(get_bits1(&s->gb))

  490.             skip_bits(&s->gb,24);//time_code

  491.         /* old sample clips were all progressive and no low_delay,

  492.            bump stream revision if detected otherwise */

  493.         if (s->low_delay || !(show_bits(&s->gb,9) & 1))

  494.             h->stream_revision = 1;

  495.         /* similarly test top_field_first and repeat_first_field */

  496.         else if(show_bits(&s->gb,11) & 3)

  497.             h->stream_revision = 1;

  498.         if(h->stream_revision > 0)

  499.             skip_bits(&s->gb,1); //marker_bit

  500.     }

  501.     /* release last B frame */

  502.     if(h->picture.f.data[0])

  503.         s->avctx->release_buffer(s->avctx, &h->picture.f);

  504. 

  505.     s->avctx->get_buffer(s->avctx, &h->picture.f);

  506.     ff_cavs_init_pic(h);

  507.     h->picture.poc = get_bits(&s->gb,8)*2;

  508. 

  509.     /* get temporal distances and MV scaling factors */

  510.     if(h->pic_type != AV_PICTURE_TYPE_B) {

  511.         h->dist[0] = (h->picture.poc - h->DPB[0].poc  + 512) % 512;

  512.     } else {

  513.         h->dist[0] = (h->DPB[0].poc  - h->picture.poc + 512) % 512;

  514.     }

  515.     h->dist[1] = (h->picture.poc - h->DPB[1].poc  + 512) % 512;

  516.     h->scale_den[0] = h->dist[0] ? 512/h->dist[0] : 0;

  517.     h->scale_den[1] = h->dist[1] ? 512/h->dist[1] : 0;

  518.     if(h->pic_type == AV_PICTURE_TYPE_B) {

  519.         h->sym_factor = h->dist[0]*h->scale_den[1];

  520.     } else {

  521.         h->direct_den[0] = h->dist[0] ? 16384/h->dist[0] : 0;

  522.         h->direct_den[1] = h->dist[1] ? 16384/h->dist[1] : 0;

  523.     }

  524. 

  525.     if(s->low_delay)

  526.         get_ue_golomb(&s->gb); //bbv_check_times

  527.     h->progressive             = get_bits1(&s->gb);

  528.     h->pic_structure = 1;

  529.     if(!h->progressive)

  530.         h->pic_structure = get_bits1(&s->gb);

  531.     if(!h->pic_structure && h->stc == PIC_PB_START_CODE)

  532.         skip_bits1(&s->gb);     //advanced_pred_mode_disable

  533.     skip_bits1(&s->gb);        //top_field_first

  534.     skip_bits1(&s->gb);        //repeat_first_field

  535.     h->qp_fixed                = get_bits1(&s->gb);

  536.     h->qp                      = get_bits(&s->gb,6);

  537.     if(h->pic_type == AV_PICTURE_TYPE_I) {

  538.         if(!h->progressive && !h->pic_structure)

  539.             skip_bits1(&s->gb);//what is this?

  540.         skip_bits(&s->gb,4);   //reserved bits

  541.     } else {

  542.         if(!(h->pic_type == AV_PICTURE_TYPE_B && h->pic_structure == 1))

  543.             h->ref_flag        = get_bits1(&s->gb);

  544.         skip_bits(&s->gb,4);   //reserved bits

  545.         h->skip_mode_flag      = get_bits1(&s->gb);

  546.     }

  547.     h->loop_filter_disable     = get_bits1(&s->gb);

  548.     if(!h->loop_filter_disable && get_bits1(&s->gb)) {

  549.         h->alpha_offset        = get_se_golomb(&s->gb);

  550.         h->beta_offset         = get_se_golomb(&s->gb);

  551.     } else {

  552.         h->alpha_offset = h->beta_offset  = 0;

  553.     }

  554.     if(h->pic_type == AV_PICTURE_TYPE_I) {

  555.         do {

  556.             check_for_slice(h);

  557.             decode_mb_i(h, 0);

  558.         } while(ff_cavs_next_mb(h));

  559.     } else if(h->pic_type == AV_PICTURE_TYPE_P) {

  560.         do {

  561.             if(check_for_slice(h))

  562.                 skip_count = -1;

  563.             if(h->skip_mode_flag && (skip_count < 0))

  564.                 skip_count = get_ue_golomb(&s->gb);

  565.             if(h->skip_mode_flag && skip_count--) {

  566.                 decode_mb_p(h,P_SKIP);

  567.             } else {

  568.                 mb_type = get_ue_golomb(&s->gb) + P_SKIP + h->skip_mode_flag;

  569.                 if(mb_type > P_8X8)

  570.                     decode_mb_i(h, mb_type - P_8X8 - 1);

  571.                 else

  572.                     decode_mb_p(h,mb_type);

  573.             }

  574.         } while(ff_cavs_next_mb(h));

  575.     } else { /* AV_PICTURE_TYPE_B */

  576.         do {

  577.             if(check_for_slice(h))

  578.                 skip_count = -1;

  579.             if(h->skip_mode_flag && (skip_count < 0))

  580.                 skip_count = get_ue_golomb(&s->gb);

  581.             if(h->skip_mode_flag && skip_count--) {

  582.                 decode_mb_b(h,B_SKIP);

  583.             } else {

  584.                 mb_type = get_ue_golomb(&s->gb) + B_SKIP + h->skip_mode_flag;

  585.                 if(mb_type > B_8X8)

  586.                     decode_mb_i(h, mb_type - B_8X8 - 1);

  587.                 else

  588.                     decode_mb_b(h,mb_type);

  589.             }

  590.         } while(ff_cavs_next_mb(h));

  591.     }

  592.     if(h->pic_type != AV_PICTURE_TYPE_B) {

  593.         if(h->DPB[1].f.data[0])

  594.             s->avctx->release_buffer(s->avctx, &h->DPB[1].f);

  595.         h->DPB[1] = h->DPB[0];

  596.         h->DPB[0] = h->picture;

  597.         memset(&h->picture,0,sizeof(Picture));

  598.     }

  599.     return 0;

  600. }

  601. 

  602. /*****************************************************************************

  603.  *

  604.  * headers and interface

  605.  *

  606.  ****************************************************************************/

  607. 

  608. static int decode_seq_header(AVSContext *h) {

  609.     MpegEncContext *s = &h->s;

  610.     int frame_rate_code;

  611. 

  612.     h->profile =         get_bits(&s->gb,8);

  613.     h->level =           get_bits(&s->gb,8);

  614.     skip_bits1(&s->gb); //progressive sequence

  615.     s->width =           get_bits(&s->gb,14);

  616.     s->height =          get_bits(&s->gb,14);

  617.     skip_bits(&s->gb,2); //chroma format

  618.     skip_bits(&s->gb,3); //sample_precision

  619.     h->aspect_ratio =    get_bits(&s->gb,4);

  620.     frame_rate_code =    get_bits(&s->gb,4);

  621.     skip_bits(&s->gb,18);//bit_rate_lower

  622.     skip_bits1(&s->gb);  //marker_bit

  623.     skip_bits(&s->gb,12);//bit_rate_upper

  624.     s->low_delay =       get_bits1(&s->gb);

  625.     h->mb_width  = (s->width  + 15) >> 4;

  626.     h->mb_height = (s->height + 15) >> 4;

  627.     h->s.avctx->time_base.den = avpriv_frame_rate_tab[frame_rate_code].num;

  628.     h->s.avctx->time_base.num = avpriv_frame_rate_tab[frame_rate_code].den;

  629.     h->s.avctx->width  = s->width;

  630.     h->s.avctx->height = s->height;

  631.     if(!h->top_qp)

  632.         ff_cavs_init_top_lines(h);

  633.     return 0;

  634. }

  635. 

  636. static void cavs_flush(AVCodecContext * avctx) {

  637.     AVSContext *h = avctx->priv_data;

  638.     h->got_keyframe = 0;

  639. }

  640. 

  641. static int cavs_decode_frame(AVCodecContext * avctx,void *data, int *data_size,

  642.                              AVPacket *avpkt) {

  643.     const uint8_t *buf = avpkt->data;

  644.     int buf_size = avpkt->size;

  645.     AVSContext *h = avctx->priv_data;

  646.     MpegEncContext *s = &h->s;

  647.     int input_size;

  648.     const uint8_t *buf_end;

  649.     const uint8_t *buf_ptr;

  650.     AVFrame *picture = data;

  651.     uint32_t stc = -1;

  652. 

  653.     s->avctx = avctx;

  654. 

  655.     if (buf_size == 0) {

  656.         if (!s->low_delay && h->DPB[0].f.data[0]) {

  657.             *data_size = sizeof(AVPicture);

  658.             *picture = h->DPB[0].f;

  659.             memset(&h->DPB[0], 0, sizeof(h->DPB[0]));

  660.         }

  661.         return 0;

  662.     }

  663. 

  664.     buf_ptr = buf;

  665.     buf_end = buf + buf_size;

  666.     for(;;) {

  667.         buf_ptr = avpriv_mpv_find_start_code(buf_ptr,buf_end, &stc);

  668.         if((stc & 0xFFFFFE00) || buf_ptr == buf_end)

  669.             return FFMAX(0, buf_ptr - buf - s->parse_context.last_index);

  670.         input_size = (buf_end - buf_ptr)*8;

  671.         switch(stc) {

  672.         case CAVS_START_CODE:

  673.             init_get_bits(&s->gb, buf_ptr, input_size);

  674.             decode_seq_header(h);

  675.             break;

  676.         case PIC_I_START_CODE:

  677.             if(!h->got_keyframe) {

  678.                 if(h->DPB[0].f.data[0])

  679.                     avctx->release_buffer(avctx, &h->DPB[0].f);

  680.                 if(h->DPB[1].f.data[0])

  681.                     avctx->release_buffer(avctx, &h->DPB[1].f);

  682.                 h->got_keyframe = 1;

  683.             }

  684.         case PIC_PB_START_CODE:

  685.             *data_size = 0;

  686.             if(!h->got_keyframe)

  687.                 break;

  688.             init_get_bits(&s->gb, buf_ptr, input_size);

  689.             h->stc = stc;

  690.             if(decode_pic(h))

  691.                 break;

  692.             *data_size = sizeof(AVPicture);

  693.             if(h->pic_type != AV_PICTURE_TYPE_B) {

  694.                 if(h->DPB[1].f.data[0]) {

  695.                     *picture = h->DPB[1].f;

  696.                 } else {

  697.                     *data_size = 0;

  698.                 }

  699.             } else

  700.                 *picture = h->picture.f;

  701.             break;

  702.         case EXT_START_CODE:

  703.             //mpeg_decode_extension(avctx,buf_ptr, input_size);

  704.             break;

  705.         case USER_START_CODE:

  706.             //mpeg_decode_user_data(avctx,buf_ptr, input_size);

  707.             break;

  708.         default:

  709.             if (stc <= SLICE_MAX_START_CODE) {

  710.                 init_get_bits(&s->gb, buf_ptr, input_size);

  711.                 decode_slice_header(h, &s->gb);

  712.             }

  713.             break;

  714.         }

  715.     }

  716. }

  717. 

  718. AVCodec ff_cavs_decoder = {

  719.     .name           = "cavs",

  720.     .type           = AVMEDIA_TYPE_VIDEO,

  721.     .id             = CODEC_ID_CAVS,

  722.     .priv_data_size = sizeof(AVSContext),

  723.     .init           = ff_cavs_init,

  724.     .close          = ff_cavs_end,

  725.     .decode         = cavs_decode_frame,

  726.     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_DELAY,

  727.     .flush          = cavs_flush,

  728.     .long_name      = NULL_IF_CONFIG_SMALL("Chinese AVS video (AVS1-P2, JiZhun profile)"),

  729. };