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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 FFmpeg.

  6.  *

  7.  * FFmpeg 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.  * FFmpeg 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 FFmpeg; 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 libavcodec/cavsdec.c

  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 {

  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.         }

  140.         level_buf[i] = level;

  141.         run_buf[i] = run;

  142.     }

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

  144.                ff_cavs_dequant_shift[qp], i))

  145.         return -1;

  146.     h->s.dsp.cavs_idct8_add(dst,block,stride);

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

  148.     return 0;

  149. }

  150. 

  151. 

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

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

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

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

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

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

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

  159. }

  160. 

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

  162.     int block;

  163. 

  164.     /* get coded block pattern */

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

  166.     if(cbp > 63){

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

  168.         return -1;

  169.     }

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

  171. 

  172.     /* get quantizer */

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

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

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

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

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

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

  179.     decode_residual_chroma(h);

  180. 

  181.     return 0;

  182. }

  183. 

  184. /*****************************************************************************

  185.  *

  186.  * macroblock level

  187.  *

  188.  ****************************************************************************/

  189. 

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

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

  192.     int block, pred_mode_uv;

  193.     uint8_t top[18];

  194.     uint8_t *left = NULL;

  195.     uint8_t *d;

  196. 

  197.     ff_cavs_init_mb(h);

  198. 

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

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

  201.         int nA,nB,predpred;

  202.         int pos = ff_cavs_scan3x3[block];

  203. 

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

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

  206.         predpred = FFMIN(nA,nB);

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

  208.             predpred = INTRA_L_LP;

  209.         if(!get_bits1(gb)){

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

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

  212.         }

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

  214.     }

  215.     pred_mode_uv = get_ue_golomb(gb);

  216.     if(pred_mode_uv > 6) {

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

  218.         return -1;

  219.     }

  220.     ff_cavs_modify_mb_i(h, &pred_mode_uv);

  221. 

  222.     /* get coded block pattern */

  223.     if(h->pic_type == FF_I_TYPE)

  224.         cbp_code = get_ue_golomb(gb);

  225.     if(cbp_code > 63){

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

  227.         return -1;

  228.     }

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

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

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

  232. 

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

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

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

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

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

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

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

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

  241.     }

  242. 

  243.     /* chroma intra prediction */

  244.     ff_cavs_load_intra_pred_chroma(h);

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

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

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

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

  249. 

  250.     decode_residual_chroma(h);

  251.     ff_cavs_filter(h,I_8X8);

  252.     set_mv_intra(h);

  253.     return 0;

  254. }

  255. 

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

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

  258.     int ref[4];

  259. 

  260.     ff_cavs_init_mb(h);

  261.     switch(mb_type) {

  262.     case P_SKIP:

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

  264.         break;

  265.     case P_16X16:

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

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

  268.         break;

  269.     case P_16X8:

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

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

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

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

  274.         break;

  275.     case P_8X16:

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

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

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

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

  280.         break;

  281.     case P_8X8:

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

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

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

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

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

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

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

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

  290.     }

  291.     ff_cavs_inter(h, mb_type);

  292.     set_intra_mode_default(h);

  293.     store_mvs(h);

  294.     if(mb_type != P_SKIP)

  295.         decode_residual_inter(h);

  296.     ff_cavs_filter(h,mb_type);

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

  298. }

  299. 

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

  301.     int block;

  302.     enum cavs_sub_mb sub_type[4];

  303.     int flags;

  304. 

  305.     ff_cavs_init_mb(h);

  306. 

  307.     /* reset all MVs */

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

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

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

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

  312.     switch(mb_type) {

  313.     case B_SKIP:

  314.     case B_DIRECT:

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

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

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

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

  319.         } else

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

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

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

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

  324.         break;

  325.     case B_FWD_16X16:

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

  327.         break;

  328.     case B_SYM_16X16:

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

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

  331.         break;

  332.     case B_BWD_16X16:

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

  334.         break;

  335.     case B_8X8:

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

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

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

  339.             switch(sub_type[block]) {

  340.             case B_SUB_DIRECT:

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

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

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

  344.                             MV_PRED_BSKIP, BLK_8X8, 1);

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

  346.                             mv_scan[block]-3+MV_BWD_OFFS,

  347.                             MV_PRED_BSKIP, BLK_8X8, 0);

  348.                 } else

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

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

  351.                 break;

  352.             case B_SUB_FWD:

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

  354.                         MV_PRED_MEDIAN, BLK_8X8, 1);

  355.                 break;

  356.             case B_SUB_SYM:

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

  358.                         MV_PRED_MEDIAN, BLK_8X8, 1);

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

  360.                 break;

  361.             }

  362.         }

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

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

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

  366.                         mv_scan[block]+MV_BWD_OFFS-3,

  367.                         MV_PRED_MEDIAN, BLK_8X8, 0);

  368.         }

  369.         break;

  370.     default:

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

  372.         flags = ff_cavs_partition_flags[mb_type];

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

  374.             if(flags & FWD0)

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

  376.             if(flags & SYM0)

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

  378.             if(flags & FWD1)

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

  380.             if(flags & SYM1)

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

  382.             if(flags & BWD0)

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

  384.             if(flags & BWD1)

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

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

  387.             if(flags & FWD0)

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

  389.             if(flags & SYM0)

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

  391.             if(flags & FWD1)

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

  393.             if(flags & SYM1)

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

  395.             if(flags & BWD0)

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

  397.             if(flags & BWD1)

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

  399.         }

  400.     }

  401.     ff_cavs_inter(h, mb_type);

  402.     set_intra_mode_default(h);

  403.     if(mb_type != B_SKIP)

  404.         decode_residual_inter(h);

  405.     ff_cavs_filter(h,mb_type);

  406. }

  407. 

  408. /*****************************************************************************

  409.  *

  410.  * slice level

  411.  *

  412.  ****************************************************************************/

  413. 

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

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

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

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

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

  419. 

  420.     /* mark top macroblocks as unavailable */

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

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

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

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

  425.     }

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

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

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

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

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

  431.         }

  432.     return 0;

  433. }

  434. 

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

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

  437.     int align;

  438. 

  439.     if(h->mbx)

  440.         return 0;

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

  442.     /* check for stuffing byte */

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

  444.         align = 8;

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

  446.         skip_bits_long(gb,24+align);

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

  448.         decode_slice_header(h,gb);

  449.         return 1;

  450.     }

  451.     return 0;

  452. }

  453. 

  454. /*****************************************************************************

  455.  *

  456.  * frame level

  457.  *

  458.  ****************************************************************************/

  459. 

  460. static int decode_pic(AVSContext *h) {

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

  462.     int skip_count = -1;

  463.     enum cavs_mb mb_type;

  464. 

  465.     if (!s->context_initialized) {

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

  467.         if (MPV_common_init(s) < 0)

  468.             return -1;

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

  470.     }

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

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

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

  474.         if(h->pic_type > FF_B_TYPE) {

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

  476.             return -1;

  477.         }

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

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

  480.           (!h->DPB[1].data[0] && h->pic_type == FF_B_TYPE))

  481.             return -1;

  482.     } else {

  483.         h->pic_type = FF_I_TYPE;

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

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

  486.     }

  487.     /* release last B frame */

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

  489.         s->avctx->release_buffer(s->avctx, (AVFrame *)&h->picture);

  490. 

  491.     s->avctx->get_buffer(s->avctx, (AVFrame *)&h->picture);

  492.     ff_cavs_init_pic(h);

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

  494. 

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

  496.     if(h->pic_type != FF_B_TYPE) {

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

  498.     } else {

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

  500.     }

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

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

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

  504.     if(h->pic_type == FF_B_TYPE) {

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

  506.     } else {

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

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

  509.     }

  510. 

  511.     if(s->low_delay)

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

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

  514.     h->pic_structure = 1;

  515.     if(!h->progressive)

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

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

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

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

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

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

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

  523.     if(h->pic_type == FF_I_TYPE) {

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

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

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

  527.     } else {

  528.         if(!(h->pic_type == FF_B_TYPE && h->pic_structure == 1))

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

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

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

  532.     }

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

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

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

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

  537.     } else {

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

  539.     }

  540.     if(h->pic_type == FF_I_TYPE) {

  541.         do {

  542.             check_for_slice(h);

  543.             decode_mb_i(h, 0);

  544.         } while(ff_cavs_next_mb(h));

  545.     } else if(h->pic_type == FF_P_TYPE) {

  546.         do {

  547.             if(check_for_slice(h))

  548.                 skip_count = -1;

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

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

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

  552.                 decode_mb_p(h,P_SKIP);

  553.             } else {

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

  555.                 if(mb_type > P_8X8)

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

  557.                 else

  558.                     decode_mb_p(h,mb_type);

  559.             }

  560.         } while(ff_cavs_next_mb(h));

  561.     } else { /* FF_B_TYPE */

  562.         do {

  563.             if(check_for_slice(h))

  564.                 skip_count = -1;

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

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

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

  568.                 decode_mb_b(h,B_SKIP);

  569.             } else {

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

  571.                 if(mb_type > B_8X8)

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

  573.                 else

  574.                     decode_mb_b(h,mb_type);

  575.             }

  576.         } while(ff_cavs_next_mb(h));

  577.     }

  578.     if(h->pic_type != FF_B_TYPE) {

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

  580.             s->avctx->release_buffer(s->avctx, (AVFrame *)&h->DPB[1]);

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

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

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

  584.     }

  585.     return 0;

  586. }

  587. 

  588. /*****************************************************************************

  589.  *

  590.  * headers and interface

  591.  *

  592.  ****************************************************************************/

  593. 

  594. static int decode_seq_header(AVSContext *h) {

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

  596.     int frame_rate_code;

  597. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  613.     h->s.avctx->time_base.den = ff_frame_rate_tab[frame_rate_code].num;

  614.     h->s.avctx->time_base.num = ff_frame_rate_tab[frame_rate_code].den;

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

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

  617.     if(!h->top_qp)

  618.         ff_cavs_init_top_lines(h);

  619.     return 0;

  620. }

  621. 

  622. static void cavs_flush(AVCodecContext * avctx) {

  623.     AVSContext *h = avctx->priv_data;

  624.     h->got_keyframe = 0;

  625. }

  626. 

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

  628.                              AVPacket *avpkt) {

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

  630.     int buf_size = avpkt->size;

  631.     AVSContext *h = avctx->priv_data;

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

  633.     int input_size;

  634.     const uint8_t *buf_end;

  635.     const uint8_t *buf_ptr;

  636.     AVFrame *picture = data;

  637.     uint32_t stc = -1;

  638. 

  639.     s->avctx = avctx;

  640. 

  641.     if (buf_size == 0) {

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

  643.             *data_size = sizeof(AVPicture);

  644.             *picture = *(AVFrame *) &h->DPB[0];

  645.         }

  646.         return 0;

  647.     }

  648. 

  649.     buf_ptr = buf;

  650.     buf_end = buf + buf_size;

  651.     for(;;) {

  652.         buf_ptr = ff_find_start_code(buf_ptr,buf_end, &stc);

  653.         if(stc & 0xFFFFFE00)

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

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

  656.         switch(stc) {

  657.         case CAVS_START_CODE:

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

  659.             decode_seq_header(h);

  660.             break;

  661.         case PIC_I_START_CODE:

  662.             if(!h->got_keyframe) {

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

  664.                     avctx->release_buffer(avctx, (AVFrame *)&h->DPB[0]);

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

  666.                     avctx->release_buffer(avctx, (AVFrame *)&h->DPB[1]);

  667.                 h->got_keyframe = 1;

  668.             }

  669.         case PIC_PB_START_CODE:

  670.             *data_size = 0;

  671.             if(!h->got_keyframe)

  672.                 break;

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

  674.             h->stc = stc;

  675.             if(decode_pic(h))

  676.                 break;

  677.             *data_size = sizeof(AVPicture);

  678.             if(h->pic_type != FF_B_TYPE) {

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

  680.                     *picture = *(AVFrame *) &h->DPB[1];

  681.                 } else {

  682.                     *data_size = 0;

  683.                 }

  684.             } else

  685.                 *picture = *(AVFrame *) &h->picture;

  686.             break;

  687.         case EXT_START_CODE:

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

  689.             break;

  690.         case USER_START_CODE:

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

  692.             break;

  693.         default:

  694.             if (stc <= SLICE_MAX_START_CODE) {

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

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

  697.             }

  698.             break;

  699.         }

  700.     }

  701. }

  702. 

  703. AVCodec cavs_decoder = {

  704.     "cavs",

  705.     CODEC_TYPE_VIDEO,

  706.     CODEC_ID_CAVS,

  707.     sizeof(AVSContext),

  708.     ff_cavs_init,

  709.     NULL,

  710.     ff_cavs_end,

  711.     cavs_decode_frame,

  712.     CODEC_CAP_DR1 | CODEC_CAP_DELAY,

  713.     .flush= cavs_flush,

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

  715. };