falkTX
/
FFmpeg
mirror of https://github.com/falkTX/FFmpeg.git
1
0
Fork 0
Code Issues 0 Releases 338 Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
43714 Commits
32 Branches
940MB
Tree: 6c180b35c4
Branches Tags
${ item.name }
Create branch ${ searchTerm }
from '6c180b35c4'
${ noResults }
FFmpeg/libavcodec/cavsdec.c

749 lines
26KB
Raw Blame History 

  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

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

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

  26.  */

  27. 

  28. #include "libavutil/avassert.h"

  29. #include "avcodec.h"

  30. #include "get_bits.h"

  31. #include "golomb.h"

  32. #include "cavs.h"

  33. 

  34. static const uint8_t mv_scan[4] = {

  35.     MV_FWD_X0,MV_FWD_X1,

  36.     MV_FWD_X2,MV_FWD_X3

  37. };

  38. 

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

  40.   {63, 0},{15,15},{31,63},{47,31},{ 0,16},{14,32},{13,47},{11,13},

  41.   { 7,14},{ 5,11},{10,12},{ 8, 5},{12,10},{61, 7},{ 4,48},{55, 3},

  42.   { 1, 2},{ 2, 8},{59, 4},{ 3, 1},{62,61},{ 9,55},{ 6,59},{29,62},

  43.   {45,29},{51,27},{23,23},{39,19},{27,30},{46,28},{53, 9},{30, 6},

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

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

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

  47.   {34,50},{50,56},{52,25},{54,22},{41,54},{56,57},{38,41},{57,38}

  48. };

  49. 

  50. /*****************************************************************************

  51.  *

  52.  * motion vector prediction

  53.  *

  54.  ****************************************************************************/

  55. 

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

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

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

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

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

  61. }

  62. 

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

  64.                                   cavs_vector *col_mv) {

  65.     cavs_vector *pmv_bw = pmv_fw + MV_BWD_OFFS;

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

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

  68. 

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

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

  71.     pmv_fw->ref = 1;

  72.     pmv_bw->ref = 0;

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

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

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

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

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

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

  79. }

  80. 

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

  82.     cavs_vector *dst = src + MV_BWD_OFFS;

  83. 

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

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

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

  87.     dst->ref = 0;

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

  89.     set_mvs(dst, size);

  90. }

  91. 

  92. /*****************************************************************************

  93.  *

  94.  * residual data decoding

  95.  *

  96.  ****************************************************************************/

  97. 

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

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

  100.     if(order) {

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

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

  103.     }

  104.     return get_ue_golomb(gb);

  105. }

  106. 

  107. /**

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

  109.  *  and add them to sample block

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

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

  112.  * @param qp quantizer

  113.  * @param dst location of sample block

  114.  * @param stride line stride in frame buffer

  115.  */

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

  117.                                  const struct dec_2dvlc *r, int esc_golomb_order,

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

  119.     int i, esc_code, level, mask;

  120.     unsigned int level_code, run;

  121.     DCTELEM level_buf[65];

  122.     uint8_t run_buf[65];

  123.     DCTELEM *block = h->block;

  124. 

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

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

  127.         if(level_code >= ESCAPE_CODE) {

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

  129.             if(run > 64)

  130.                 return -1;

  131.             esc_code = get_ue_code(gb,esc_golomb_order);

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

  133.             while(level > r->inc_limit)

  134.                 r++;

  135.             mask = -(level_code & 1);

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

  137.         } else {

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

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

  140.                 break;

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

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

  143.         }

  144.         level_buf[i] = level;

  145.         run_buf[i] = run;

  146.     }

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

  148.                ff_cavs_dequant_shift[qp], i))

  149.         return -1;

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

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

  152.     return 0;

  153. }

  154. 

  155. 

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

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

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

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

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

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

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

  163. }

  164. 

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

  166.     int block;

  167. 

  168.     /* get coded block pattern */

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

  170.     if(cbp > 63U){

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

  172.         return -1;

  173.     }

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

  175. 

  176.     /* get quantizer */

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

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

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

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

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

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

  183.     decode_residual_chroma(h);

  184. 

  185.     return 0;

  186. }

  187. 

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

  189.  *

  190.  * macroblock level

  191.  *

  192.  ****************************************************************************/

  193. 

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

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

  196.     unsigned pred_mode_uv;

  197.     int block;

  198.     uint8_t top[18];

  199.     uint8_t *left = NULL;

  200.     uint8_t *d;

  201. 

  202.     ff_cavs_init_mb(h);

  203. 

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

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

  206.         int nA,nB,predpred;

  207.         int pos = ff_cavs_scan3x3[block];

  208. 

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

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

  211.         predpred = FFMIN(nA,nB);

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

  213.             predpred = INTRA_L_LP;

  214.         if(!get_bits1(gb)){

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

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

  217.         }

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

  219.     }

  220.     pred_mode_uv = get_ue_golomb(gb);

  221.     if(pred_mode_uv > 6) {

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

  223.         return -1;

  224.     }

  225.     ff_cavs_modify_mb_i(h, &pred_mode_uv);

  226. 

  227.     /* get coded block pattern */

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

  229.         cbp_code = get_ue_golomb(gb);

  230.     if(cbp_code > 63U){

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

  232.         return -1;

  233.     }

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

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

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

  237. 

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

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

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

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

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

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

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

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

  246.     }

  247. 

  248.     /* chroma intra prediction */

  249.     ff_cavs_load_intra_pred_chroma(h);

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

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

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

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

  254. 

  255.     decode_residual_chroma(h);

  256.     ff_cavs_filter(h,I_8X8);

  257.     set_mv_intra(h);

  258.     return 0;

  259. }

  260. 

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

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

  263.     int ref[4];

  264. 

  265.     ff_cavs_init_mb(h);

  266.     switch(mb_type) {

  267.     case P_SKIP:

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

  269.         break;

  270.     case P_16X16:

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

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

  273.         break;

  274.     case P_16X8:

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

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

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

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

  279.         break;

  280.     case P_8X16:

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

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

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

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

  285.         break;

  286.     case P_8X8:

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

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

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

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

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

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

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

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

  295.     }

  296.     ff_cavs_inter(h, mb_type);

  297.     set_intra_mode_default(h);

  298.     store_mvs(h);

  299.     if(mb_type != P_SKIP)

  300.         decode_residual_inter(h);

  301.     ff_cavs_filter(h,mb_type);

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

  303. }

  304. 

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

  306.     int block;

  307.     enum cavs_sub_mb sub_type[4];

  308.     int flags;

  309. 

  310.     ff_cavs_init_mb(h);

  311. 

  312.     /* reset all MVs */

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

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

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

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

  317.     switch(mb_type) {

  318.     case B_SKIP:

  319.     case B_DIRECT:

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

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

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

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

  324.         } else

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

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

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

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

  329.         break;

  330.     case B_FWD_16X16:

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

  332.         break;

  333.     case B_SYM_16X16:

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

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

  336.         break;

  337.     case B_BWD_16X16:

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

  339.         break;

  340.     case B_8X8:

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

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

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

  344.             switch(sub_type[block]) {

  345.             case B_SUB_DIRECT:

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

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

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

  349.                             MV_PRED_BSKIP, BLK_8X8, 1);

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

  351.                             mv_scan[block]-3+MV_BWD_OFFS,

  352.                             MV_PRED_BSKIP, BLK_8X8, 0);

  353.                 } else

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

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

  356.                 break;

  357.             case B_SUB_FWD:

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

  359.                         MV_PRED_MEDIAN, BLK_8X8, 1);

  360.                 break;

  361.             case B_SUB_SYM:

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

  363.                         MV_PRED_MEDIAN, BLK_8X8, 1);

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

  365.                 break;

  366.             }

  367.         }

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

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

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

  371.                         mv_scan[block]+MV_BWD_OFFS-3,

  372.                         MV_PRED_MEDIAN, BLK_8X8, 0);

  373.         }

  374.         break;

  375.     default:

  376.         av_assert2((mb_type > B_SYM_16X16) && (mb_type < B_8X8));

  377.         flags = ff_cavs_partition_flags[mb_type];

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

  379.             if(flags & FWD0)

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

  381.             if(flags & SYM0)

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

  383.             if(flags & FWD1)

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

  385.             if(flags & SYM1)

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

  387.             if(flags & BWD0)

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

  389.             if(flags & BWD1)

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

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

  392.             if(flags & FWD0)

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

  394.             if(flags & SYM0)

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

  396.             if(flags & FWD1)

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

  398.             if(flags & SYM1)

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

  400.             if(flags & BWD0)

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

  402.             if(flags & BWD1)

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

  404.         }

  405.     }

  406.     ff_cavs_inter(h, mb_type);

  407.     set_intra_mode_default(h);

  408.     if(mb_type != B_SKIP)

  409.         decode_residual_inter(h);

  410.     ff_cavs_filter(h,mb_type);

  411. }

  412. 

  413. /*****************************************************************************

  414.  *

  415.  * slice level

  416.  *

  417.  ****************************************************************************/

  418. 

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

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

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

  422. 

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

  424.         return -1;

  425. 

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

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

  428. 

  429.     /* mark top macroblocks as unavailable */

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

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

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

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

  434.     }

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

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

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

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

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

  440.         }

  441.     return 0;

  442. }

  443. 

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

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

  446.     int align;

  447. 

  448.     if(h->mbx)

  449.         return 0;

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

  451.     /* check for stuffing byte */

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

  453.         align = 8;

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

  455.         skip_bits_long(gb,24+align);

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

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

  458.             return 0;

  459.         decode_slice_header(h,gb);

  460.         return 1;

  461.     }

  462.     return 0;

  463. }

  464. 

  465. /*****************************************************************************

  466.  *

  467.  * frame level

  468.  *

  469.  ****************************************************************************/

  470. 

  471. static int decode_pic(AVSContext *h) {

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

  473.     int skip_count = -1;

  474.     enum cavs_mb mb_type;

  475. 

  476.     if (!s->context_initialized) {

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

  478.         if (ff_MPV_common_init(s) < 0)

  479.             return -1;

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

  481.     }

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

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

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

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

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

  487.             return -1;

  488.         }

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

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

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

  492.             return -1;

  493.     } else {

  494.         h->pic_type = AV_PICTURE_TYPE_I;

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

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

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

  498.            bump stream revision if detected otherwise */

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

  500.             h->stream_revision = 1;

  501.         /* similarly test top_field_first and repeat_first_field */

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

  503.             h->stream_revision = 1;

  504.         if(h->stream_revision > 0)

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

  506.     }

  507.     /* release last B frame */

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

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

  510. 

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

  512.     ff_cavs_init_pic(h);

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

  514. 

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

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

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

  518.     } else {

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

  520.     }

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

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

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

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

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

  526.     } else {

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

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

  529.     }

  530. 

  531.     if(s->low_delay)

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

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

  534.     h->pic_structure = 1;

  535.     if(!h->progressive)

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

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

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

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

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

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

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

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

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

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

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

  547.     } else {

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

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

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

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

  552.     }

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

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

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

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

  557.     } else {

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

  559.     }

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

  561.         do {

  562.             check_for_slice(h);

  563.             decode_mb_i(h, 0);

  564.         } while(ff_cavs_next_mb(h));

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

  566.         do {

  567.             if(check_for_slice(h))

  568.                 skip_count = -1;

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

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

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

  572.                 decode_mb_p(h,P_SKIP);

  573.             } else {

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

  575.                 if(mb_type > P_8X8)

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

  577.                 else

  578.                     decode_mb_p(h,mb_type);

  579.             }

  580.         } while(ff_cavs_next_mb(h));

  581.     } else { /* AV_PICTURE_TYPE_B */

  582.         do {

  583.             if(check_for_slice(h))

  584.                 skip_count = -1;

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

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

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

  588.                 decode_mb_b(h,B_SKIP);

  589.             } else {

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

  591.                 if(mb_type > B_8X8)

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

  593.                 else

  594.                     decode_mb_b(h,mb_type);

  595.             }

  596.         } while(ff_cavs_next_mb(h));

  597.     }

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

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

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

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

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

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

  604.     }

  605.     return 0;

  606. }

  607. 

  608. /*****************************************************************************

  609.  *

  610.  * headers and interface

  611.  *

  612.  ****************************************************************************/

  613. 

  614. static int decode_seq_header(AVSContext *h) {

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

  616.     int frame_rate_code;

  617.     int width, height;

  618. 

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

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

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

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

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

  624.     if ((s->width || s->height) && (s->width != width || s->height != height)) {

  625.         av_log_missing_feature(s, "Width/height changing in CAVS is", 0);

  626.         return -1;

  627.     }

  628.     if (width <= 0 || height <= 0) {

  629.         av_log(s, AV_LOG_ERROR, "Dimensions invalid\n");

  630.         return AVERROR_INVALIDDATA;

  631.     }

  632.     s->width  = width;

  633.     s->height = height;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  648.     if(!h->top_qp)

  649.         ff_cavs_init_top_lines(h);

  650.     return 0;

  651. }

  652. 

  653. static void cavs_flush(AVCodecContext * avctx) {

  654.     AVSContext *h = avctx->priv_data;

  655.     h->got_keyframe = 0;

  656. }

  657. 

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

  659.                              AVPacket *avpkt) {

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

  661.     int buf_size = avpkt->size;

  662.     AVSContext *h = avctx->priv_data;

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

  664.     int input_size;

  665.     const uint8_t *buf_end;

  666.     const uint8_t *buf_ptr;

  667.     AVFrame *picture = data;

  668.     uint32_t stc = -1;

  669. 

  670.     s->avctx = avctx;

  671. 

  672.     if (buf_size == 0) {

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

  674.             *data_size = sizeof(AVPicture);

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

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

  677.         }

  678.         return 0;

  679.     }

  680. 

  681.     buf_ptr = buf;

  682.     buf_end = buf + buf_size;

  683.     for(;;) {

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

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

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

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

  688.         switch(stc) {

  689.         case CAVS_START_CODE:

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

  691.             decode_seq_header(h);

  692.             break;

  693.         case PIC_I_START_CODE:

  694.             if(!h->got_keyframe) {

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

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

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

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

  699.                 h->got_keyframe = 1;

  700.             }

  701.         case PIC_PB_START_CODE:

  702.             *data_size = 0;

  703.             if(!h->got_keyframe)

  704.                 break;

  705.             if(!h->top_qp)

  706.                 break;

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

  708.             h->stc = stc;

  709.             if(decode_pic(h))

  710.                 break;

  711.             *data_size = sizeof(AVPicture);

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

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

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

  715.                 } else {

  716.                     *data_size = 0;

  717.                 }

  718.             } else

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

  720.             break;

  721.         case EXT_START_CODE:

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

  723.             break;

  724.         case USER_START_CODE:

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

  726.             break;

  727.         default:

  728.             if (stc <= SLICE_MAX_START_CODE) {

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

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

  731.             }

  732.             break;

  733.         }

  734.     }

  735. }

  736. 

  737. AVCodec ff_cavs_decoder = {

  738.     .name           = "cavs",

  739.     .type           = AVMEDIA_TYPE_VIDEO,

  740.     .id             = AV_CODEC_ID_CAVS,

  741.     .priv_data_size = sizeof(AVSContext),

  742.     .init           = ff_cavs_init,

  743.     .close          = ff_cavs_end,

  744.     .decode         = cavs_decode_frame,

  745.     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_DELAY,

  746.     .flush          = cavs_flush,

  747.     .long_name      = NULL_IF_CONFIG_SMALL("Chinese AVS (Audio Video Standard) (AVS1-P2, JiZhun profile)"),

  748. };