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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 cavs.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 "bitstream.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->mby*h->mb_width + h->mbx)*4 + 0] = h->mv[MV_FWD_X0];

  57.     h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 1] = h->mv[MV_FWD_X1];

  58.     h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 2] = h->mv[MV_FWD_X2];

  59.     h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 3] = h->mv[MV_FWD_X3];

  60. }

  61. 

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

  63.                                   vector_t *col_mv) {

  64.     vector_t *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, vector_t *src, enum block_t size) {

  81.     vector_t *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 dec_2dvlc_t *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[64];

  120.     uint8_t run_buf[64];

  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.     return 0;

  148. }

  149. 

  150. 

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

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

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

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

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

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

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

  158. }

  159. 

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

  161.     int block;

  162. 

  163.     /* get coded block pattern */

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

  165.     if(cbp > 63){

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

  167.         return -1;

  168.     }

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

  170. 

  171.     /* get quantizer */

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

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

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

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

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

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

  178.     decode_residual_chroma(h);

  179. 

  180.     return 0;

  181. }

  182. 

  183. /*****************************************************************************

  184.  *

  185.  * macroblock level

  186.  *

  187.  ****************************************************************************/

  188. 

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

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

  191.     int block, pred_mode_uv;

  192.     uint8_t top[18];

  193.     uint8_t *left = NULL;

  194.     uint8_t *d;

  195. 

  196.     ff_cavs_init_mb(h);

  197. 

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

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

  200.         int nA,nB,predpred;

  201.         int pos = ff_cavs_scan3x3[block];

  202. 

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

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

  205.         predpred = FFMIN(nA,nB);

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

  207.             predpred = INTRA_L_LP;

  208.         if(!get_bits1(gb)){

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

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

  211.         }

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

  213.     }

  214.     pred_mode_uv = get_ue_golomb(gb);

  215.     if(pred_mode_uv > 6) {

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

  217.         return -1;

  218.     }

  219.     ff_cavs_modify_mb_i(h, &pred_mode_uv);

  220. 

  221.     /* get coded block pattern */

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

  223.         cbp_code = get_ue_golomb(gb);

  224.     if(cbp_code > 63){

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

  226.         return -1;

  227.     }

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

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

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

  231. 

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

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

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

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

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

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

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

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

  240.     }

  241. 

  242.     /* chroma intra prediction */

  243.     ff_cavs_load_intra_pred_chroma(h);

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

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

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

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

  248. 

  249.     decode_residual_chroma(h);

  250.     ff_cavs_filter(h,I_8X8);

  251.     set_mv_intra(h);

  252.     return 0;

  253. }

  254. 

  255. static void decode_mb_p(AVSContext *h, enum mb_t mb_type) {

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

  257.     int ref[4];

  258. 

  259.     ff_cavs_init_mb(h);

  260.     switch(mb_type) {

  261.     case P_SKIP:

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

  263.         break;

  264.     case P_16X16:

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

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

  267.         break;

  268.     case P_16X8:

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

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

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

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

  273.         break;

  274.     case P_8X16:

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

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

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

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

  279.         break;

  280.     case P_8X8:

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

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

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

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

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

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

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

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

  289.     }

  290.     ff_cavs_inter(h, mb_type);

  291.     set_intra_mode_default(h);

  292.     store_mvs(h);

  293.     if(mb_type != P_SKIP)

  294.         decode_residual_inter(h);

  295.     ff_cavs_filter(h,mb_type);

  296.     *h->col_type = mb_type;

  297. }

  298. 

  299. static void decode_mb_b(AVSContext *h, enum mb_t mb_type) {

  300.     int block;

  301.     enum sub_mb_t sub_type[4];

  302.     int flags;

  303. 

  304.     ff_cavs_init_mb(h);

  305. 

  306.     /* reset all MVs */

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

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

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

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

  311.     switch(mb_type) {

  312.     case B_SKIP:

  313.     case B_DIRECT:

  314.         if(!(*h->col_type)) {

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

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

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

  318.         } else

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

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

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

  322.                             &h->col_mv[(h->mby*h->mb_width+h->mbx)*4 + block]);

  323.         break;

  324.     case B_FWD_16X16:

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

  326.         break;

  327.     case B_SYM_16X16:

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

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

  330.         break;

  331.     case B_BWD_16X16:

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

  333.         break;

  334.     case B_8X8:

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

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

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

  338.             switch(sub_type[block]) {

  339.             case B_SUB_DIRECT:

  340.                 if(!(*h->col_type)) {

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

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

  343.                             MV_PRED_BSKIP, BLK_8X8, 1);

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

  345.                             mv_scan[block]-3+MV_BWD_OFFS,

  346.                             MV_PRED_BSKIP, BLK_8X8, 0);

  347.                 } else

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

  349.                                    &h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + block]);

  350.                 break;

  351.             case B_SUB_FWD:

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

  353.                         MV_PRED_MEDIAN, BLK_8X8, 1);

  354.                 break;

  355.             case B_SUB_SYM:

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

  357.                         MV_PRED_MEDIAN, BLK_8X8, 1);

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

  359.                 break;

  360.             }

  361.         }

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

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

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

  365.                         mv_scan[block]+MV_BWD_OFFS-3,

  366.                         MV_PRED_MEDIAN, BLK_8X8, 0);

  367.         }

  368.         break;

  369.     default:

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

  371.         flags = ff_cavs_partition_flags[mb_type];

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

  373.             if(flags & FWD0)

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

  375.             if(flags & SYM0)

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

  377.             if(flags & FWD1)

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

  379.             if(flags & SYM1)

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

  381.             if(flags & BWD0)

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

  383.             if(flags & BWD1)

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

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

  386.             if(flags & FWD0)

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

  388.             if(flags & SYM0)

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

  390.             if(flags & FWD1)

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

  392.             if(flags & SYM1)

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

  394.             if(flags & BWD0)

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

  396.             if(flags & BWD1)

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

  398.         }

  399.     }

  400.     ff_cavs_inter(h, mb_type);

  401.     set_intra_mode_default(h);

  402.     if(mb_type != B_SKIP)

  403.         decode_residual_inter(h);

  404.     ff_cavs_filter(h,mb_type);

  405. }

  406. 

  407. /*****************************************************************************

  408.  *

  409.  * slice level

  410.  *

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

  412. 

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

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

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

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

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

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

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

  420.     }

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

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

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

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

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

  426.         }

  427.     return 0;

  428. }

  429. 

  430. static inline void check_for_slice(AVSContext *h) {

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

  432.     int align;

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

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

  435.         skip_bits_long(gb,24+align);

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

  437.         decode_slice_header(h,gb);

  438.     }

  439. }

  440. 

  441. /*****************************************************************************

  442.  *

  443.  * frame level

  444.  *

  445.  ****************************************************************************/

  446. 

  447. static int decode_pic(AVSContext *h) {

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

  449.     int skip_count;

  450.     enum mb_t mb_type;

  451. 

  452.     if (!s->context_initialized) {

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

  454.         if (MPV_common_init(s) < 0)

  455.             return -1;

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

  457.     }

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

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

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

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

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

  463.             return -1;

  464.         }

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

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

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

  468.             return -1;

  469.     } else {

  470.         h->pic_type = FF_I_TYPE;

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

  472.             skip_bits(&s->gb,16);//time_code

  473.     }

  474.     /* release last B frame */

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

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

  477. 

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

  479.     ff_cavs_init_pic(h);

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

  481. 

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

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

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

  485.     } else {

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

  487.     }

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

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

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

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

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

  493.     } else {

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

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

  496.     }

  497. 

  498.     if(s->low_delay)

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

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

  501.     if(h->progressive)

  502.         h->pic_structure = 1;

  503.     else if(!(h->pic_structure = get_bits1(&s->gb) && (h->stc == PIC_PB_START_CODE)) )

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

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

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

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

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

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

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

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

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

  513.     } else {

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

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

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

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

  518.     }

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

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

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

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

  523.     } else {

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

  525.     }

  526.     check_for_slice(h);

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

  528.         do {

  529.             decode_mb_i(h, 0);

  530.         } while(ff_cavs_next_mb(h));

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

  532.         do {

  533.             if(h->skip_mode_flag) {

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

  535.                 while(skip_count--) {

  536.                     decode_mb_p(h,P_SKIP);

  537.                     if(!ff_cavs_next_mb(h))

  538.                         goto done;

  539.                 }

  540.                 mb_type = get_ue_golomb(&s->gb) + P_16X16;

  541.             } else

  542.                 mb_type = get_ue_golomb(&s->gb) + P_SKIP;

  543.             if(mb_type > P_8X8) {

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

  545.             } else

  546.                 decode_mb_p(h,mb_type);

  547.         } while(ff_cavs_next_mb(h));

  548.     } else { /* FF_B_TYPE */

  549.         do {

  550.             if(h->skip_mode_flag) {

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

  552.                 while(skip_count--) {

  553.                     decode_mb_b(h,B_SKIP);

  554.                     if(!ff_cavs_next_mb(h))

  555.                         goto done;

  556.                 }

  557.                 mb_type = get_ue_golomb(&s->gb) + B_DIRECT;

  558.             } else

  559.                 mb_type = get_ue_golomb(&s->gb) + B_SKIP;

  560.             if(mb_type > B_8X8) {

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

  562.             } else

  563.                 decode_mb_b(h,mb_type);

  564.         } while(ff_cavs_next_mb(h));

  565.     }

  566.  done:

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

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

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

  570.         memcpy(&h->DPB[1], &h->DPB[0], sizeof(Picture));

  571.         memcpy(&h->DPB[0], &h->picture, sizeof(Picture));

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

  573.     }

  574.     return 0;

  575. }

  576. 

  577. /*****************************************************************************

  578.  *

  579.  * headers and interface

  580.  *

  581.  ****************************************************************************/

  582. 

  583. static int decode_seq_header(AVSContext *h) {

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

  585.     int frame_rate_code;

  586. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  606.     if(!h->top_qp)

  607.         ff_cavs_init_top_lines(h);

  608.     return 0;

  609. }

  610. 

  611. static void cavs_flush(AVCodecContext * avctx) {

  612.     AVSContext *h = avctx->priv_data;

  613.     h->got_keyframe = 0;

  614. }

  615. 

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

  617.                              uint8_t * buf, int buf_size) {

  618.     AVSContext *h = avctx->priv_data;

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

  620.     int input_size;

  621.     const uint8_t *buf_end;

  622.     const uint8_t *buf_ptr;

  623.     AVFrame *picture = data;

  624.     uint32_t stc = -1;

  625. 

  626.     s->avctx = avctx;

  627. 

  628.     if (buf_size == 0) {

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

  630.             *data_size = sizeof(AVPicture);

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

  632.         }

  633.         return 0;

  634.     }

  635. 

  636.     buf_ptr = buf;

  637.     buf_end = buf + buf_size;

  638.     for(;;) {

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

  640.         if(stc & 0xFFFFFE00)

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

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

  643.         switch(stc) {

  644.         case CAVS_START_CODE:

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

  646.             decode_seq_header(h);

  647.             break;

  648.         case PIC_I_START_CODE:

  649.             if(!h->got_keyframe) {

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

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

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

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

  654.                 h->got_keyframe = 1;

  655.             }

  656.         case PIC_PB_START_CODE:

  657.             *data_size = 0;

  658.             if(!h->got_keyframe)

  659.                 break;

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

  661.             h->stc = stc;

  662.             if(decode_pic(h))

  663.                 break;

  664.             *data_size = sizeof(AVPicture);

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

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

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

  668.                 } else {

  669.                     *data_size = 0;

  670.                 }

  671.             } else

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

  673.             break;

  674.         case EXT_START_CODE:

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

  676.             break;

  677.         case USER_START_CODE:

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

  679.             break;

  680.         default:

  681.             if (stc >= SLICE_MIN_START_CODE &&

  682.                 stc <= SLICE_MAX_START_CODE) {

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

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

  685.             }

  686.             break;

  687.         }

  688.     }

  689. }

  690. 

  691. AVCodec cavs_decoder = {

  692.     "cavs",

  693.     CODEC_TYPE_VIDEO,

  694.     CODEC_ID_CAVS,

  695.     sizeof(AVSContext),

  696.     ff_cavs_init,

  697.     NULL,

  698.     ff_cavs_end,

  699.     cavs_decode_frame,

  700.     CODEC_CAP_DR1 | CODEC_CAP_DELAY,

  701.     .flush= cavs_flush,

  702. };