LCOV - code coverage report
Current view: top level - libavcodec - mss4.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 279 314 88.9 %
Date: 2017-12-14 01:15:32 Functions: 14 14 100.0 %

          Line data    Source code
       1             : /*
       2             :  * Microsoft Screen 4 (aka Microsoft Expression Encoder Screen) decoder
       3             :  * Copyright (c) 2012 Konstantin Shishkov
       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             :  * Microsoft Screen 4 (aka Microsoft Titanium Screen 2,
      25             :  * aka Microsoft Expression Encoder Screen) decoder
      26             :  */
      27             : 
      28             : #include "avcodec.h"
      29             : #include "bytestream.h"
      30             : #include "get_bits.h"
      31             : #include "internal.h"
      32             : #include "mss34dsp.h"
      33             : #include "unary.h"
      34             : 
      35             : #define HEADER_SIZE 8
      36             : 
      37             : enum FrameType {
      38             :     INTRA_FRAME = 0,
      39             :     INTER_FRAME,
      40             :     SKIP_FRAME
      41             : };
      42             : 
      43             : enum BlockType {
      44             :     SKIP_BLOCK = 0,
      45             :     DCT_BLOCK,
      46             :     IMAGE_BLOCK,
      47             : };
      48             : 
      49             : enum CachePos {
      50             :     LEFT = 0,
      51             :     TOP_LEFT,
      52             :     TOP,
      53             : };
      54             : 
      55             : static const uint8_t mss4_dc_vlc_lens[2][16] = {
      56             :     { 0, 1, 5, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 },
      57             :     { 0, 3, 1, 1, 1, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0 }
      58             : };
      59             : 
      60             : static const uint8_t mss4_ac_vlc_lens[2][16] = {
      61             :     { 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 125 },
      62             :     { 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 119 }
      63             : };
      64             : 
      65             : static const uint8_t mss4_ac_vlc_syms[2][162] = {
      66             :   { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
      67             :     0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
      68             :     0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xA1, 0x08,
      69             :     0x23, 0x42, 0xB1, 0xC1, 0x15, 0x52, 0xD1, 0xF0,
      70             :     0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0A, 0x16,
      71             :     0x17, 0x18, 0x19, 0x1A, 0x25, 0x26, 0x27, 0x28,
      72             :     0x29, 0x2A, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
      73             :     0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
      74             :     0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
      75             :     0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
      76             :     0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
      77             :     0x7A, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
      78             :     0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
      79             :     0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7,
      80             :     0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6,
      81             :     0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5,
      82             :     0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4,
      83             :     0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xE1, 0xE2,
      84             :     0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
      85             :     0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
      86             :     0xF9, 0xFA  },
      87             :   { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
      88             :     0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
      89             :     0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
      90             :     0xA1, 0xB1, 0xC1, 0x09, 0x23, 0x33, 0x52, 0xF0,
      91             :     0x15, 0x62, 0x72, 0xD1, 0x0A, 0x16, 0x24, 0x34,
      92             :     0xE1, 0x25, 0xF1, 0x17, 0x18, 0x19, 0x1A, 0x26,
      93             :     0x27, 0x28, 0x29, 0x2A, 0x35, 0x36, 0x37, 0x38,
      94             :     0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
      95             :     0x49, 0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
      96             :     0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
      97             :     0x69, 0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
      98             :     0x79, 0x7A, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
      99             :     0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96,
     100             :     0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5,
     101             :     0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4,
     102             :     0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3,
     103             :     0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2,
     104             :     0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA,
     105             :     0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9,
     106             :     0xEA, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
     107             :     0xF9, 0xFA  }
     108             : };
     109             : 
     110             : static const uint8_t vec_len_syms[2][4] = {
     111             :     { 4, 2, 3, 1 },
     112             :     { 4, 1, 2, 3 }
     113             : };
     114             : 
     115             : static const uint8_t mss4_vec_entry_vlc_lens[2][16] = {
     116             :     { 0, 2, 2, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
     117             :     { 0, 1, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
     118             : };
     119             : 
     120             : static const uint8_t mss4_vec_entry_vlc_syms[2][9] = {
     121             :     { 0, 7, 6, 5, 8, 4, 3, 1, 2 },
     122             :     { 0, 2, 3, 4, 5, 6, 7, 1, 8 }
     123             : };
     124             : 
     125             : #define MAX_ENTRIES  162
     126             : 
     127             : typedef struct MSS4Context {
     128             :     AVFrame    *pic;
     129             : 
     130             :     VLC        dc_vlc[2], ac_vlc[2];
     131             :     VLC        vec_entry_vlc[2];
     132             :     int        block[64];
     133             :     uint8_t    imgbuf[3][16 * 16];
     134             : 
     135             :     int        quality;
     136             :     uint16_t   quant_mat[2][64];
     137             : 
     138             :     int        *prev_dc[3];
     139             :     ptrdiff_t  dc_stride[3];
     140             :     int        dc_cache[4][4];
     141             : 
     142             :     int        prev_vec[3][4];
     143             : } MSS4Context;
     144             : 
     145          24 : static av_cold int mss4_init_vlc(VLC *vlc, const uint8_t *lens,
     146             :                                  const uint8_t *syms, int num_syms)
     147             : {
     148             :     uint8_t  bits[MAX_ENTRIES];
     149             :     uint16_t codes[MAX_ENTRIES];
     150             :     int i, j;
     151          24 :     int prefix = 0, max_bits = 0, idx = 0;
     152             : 
     153         408 :     for (i = 0; i < 16; i++) {
     154        1848 :         for (j = 0; j < lens[i]; j++) {
     155        1464 :             bits[idx]  = i + 1;
     156        1464 :             codes[idx] = prefix++;
     157        1464 :             max_bits   = i + 1;
     158        1464 :             idx++;
     159             :         }
     160         384 :         prefix <<= 1;
     161             :     }
     162             : 
     163          24 :     return ff_init_vlc_sparse(vlc, FFMIN(max_bits, 9), num_syms, bits, 1, 1,
     164             :                               codes, 2, 2, syms, 1, 1, 0);
     165             : }
     166             : 
     167           4 : static av_cold int mss4_init_vlcs(MSS4Context *ctx)
     168             : {
     169             :     int ret, i;
     170             : 
     171          12 :     for (i = 0; i < 2; i++) {
     172           8 :         ret = mss4_init_vlc(&ctx->dc_vlc[i], mss4_dc_vlc_lens[i], NULL, 12);
     173           8 :         if (ret)
     174           0 :             return ret;
     175           8 :         ret = mss4_init_vlc(&ctx->ac_vlc[i], mss4_ac_vlc_lens[i],
     176           8 :                             mss4_ac_vlc_syms[i], 162);
     177           8 :         if (ret)
     178           0 :             return ret;
     179           8 :         ret = mss4_init_vlc(&ctx->vec_entry_vlc[i], mss4_vec_entry_vlc_lens[i],
     180           8 :                             mss4_vec_entry_vlc_syms[i], 9);
     181           8 :         if (ret)
     182           0 :             return ret;
     183             :     }
     184           4 :     return 0;
     185             : }
     186             : 
     187           4 : static av_cold void mss4_free_vlcs(MSS4Context *ctx)
     188             : {
     189             :     int i;
     190             : 
     191          12 :     for (i = 0; i < 2; i++) {
     192           8 :         ff_free_vlc(&ctx->dc_vlc[i]);
     193           8 :         ff_free_vlc(&ctx->ac_vlc[i]);
     194           8 :         ff_free_vlc(&ctx->vec_entry_vlc[i]);
     195             :     }
     196           4 : }
     197             : 
     198             : /* This function returns values in the range
     199             :  * (-range + 1; -range/2] U [range/2; range - 1)
     200             :  * i.e.
     201             :  * nbits = 0 -> 0
     202             :  * nbits = 1 -> -1, 1
     203             :  * nbits = 2 -> -3, -2, 2, 3
     204             :  */
     205      315916 : static av_always_inline int get_coeff_bits(GetBitContext *gb, int nbits)
     206             : {
     207             :     int val;
     208             : 
     209      315916 :     if (!nbits)
     210      133329 :         return 0;
     211             : 
     212      182587 :     val = get_bits(gb, nbits);
     213      182587 :     if (val < (1 << (nbits - 1)))
     214       98069 :         val -= (1 << nbits) - 1;
     215             : 
     216      182587 :     return val;
     217             : }
     218             : 
     219      180586 : static inline int get_coeff(GetBitContext *gb, VLC *vlc)
     220             : {
     221      180586 :     int val = get_vlc2(gb, vlc->table, vlc->bits, 2);
     222             : 
     223      180586 :     return get_coeff_bits(gb, val);
     224             : }
     225             : 
     226       85284 : static int mss4_decode_dct(GetBitContext *gb, VLC *dc_vlc, VLC *ac_vlc,
     227             :                            int *block, int *dc_cache,
     228             :                            int bx, int by, uint16_t *quant_mat)
     229             : {
     230       85284 :     int skip, val, pos = 1, zz_pos, dc;
     231             : 
     232       85284 :     memset(block, 0, sizeof(*block) * 64);
     233             : 
     234       85284 :     dc = get_coeff(gb, dc_vlc);
     235             :     // DC prediction is the same as in MSS3
     236       85284 :     if (by) {
     237       84904 :         if (bx) {
     238             :             int l, tl, t;
     239             : 
     240       83868 :             l  = dc_cache[LEFT];
     241       83868 :             tl = dc_cache[TOP_LEFT];
     242       83868 :             t  = dc_cache[TOP];
     243             : 
     244       83868 :             if (FFABS(t - tl) <= FFABS(l - tl))
     245       80876 :                 dc += l;
     246             :             else
     247        2992 :                 dc += t;
     248             :         } else {
     249        1036 :             dc += dc_cache[TOP];
     250             :         }
     251         380 :     } else if (bx) {
     252         380 :         dc += dc_cache[LEFT];
     253             :     }
     254       85284 :     dc_cache[LEFT] = dc;
     255       85284 :     block[0]       = dc * quant_mat[0];
     256             : 
     257      305966 :     while (pos < 64) {
     258      219785 :         val = get_vlc2(gb, ac_vlc->table, 9, 2);
     259      219785 :         if (!val)
     260       84387 :             return 0;
     261      135398 :         if (val == -1)
     262           0 :             return -1;
     263      135398 :         if (val == 0xF0) {
     264          68 :             pos += 16;
     265          68 :             continue;
     266             :         }
     267      135330 :         skip = val >> 4;
     268      135330 :         val  = get_coeff_bits(gb, val & 0xF);
     269      135330 :         pos += skip;
     270      135330 :         if (pos >= 64)
     271           0 :             return -1;
     272             : 
     273      135330 :         zz_pos = ff_zigzag_direct[pos];
     274      135330 :         block[zz_pos] = val * quant_mat[zz_pos];
     275      135330 :         pos++;
     276             :     }
     277             : 
     278         897 :     return pos == 64 ? 0 : -1;
     279             : }
     280             : 
     281       14214 : static int mss4_decode_dct_block(MSS4Context *c, GetBitContext *gb,
     282             :                                  uint8_t *dst[3], int mb_x, int mb_y)
     283             : {
     284             :     int i, j, k, ret;
     285       14214 :     uint8_t *out = dst[0];
     286             : 
     287       42642 :     for (j = 0; j < 2; j++) {
     288       85284 :         for (i = 0; i < 2; i++) {
     289       56856 :             int xpos = mb_x * 2 + i;
     290       56856 :             c->dc_cache[j][TOP_LEFT] = c->dc_cache[j][TOP];
     291       56856 :             c->dc_cache[j][TOP]      = c->prev_dc[0][mb_x * 2 + i];
     292      113712 :             ret = mss4_decode_dct(gb, c->dc_vlc, c->ac_vlc, c->block,
     293       56856 :                                   c->dc_cache[j],
     294       56856 :                                   xpos, mb_y * 2 + j, c->quant_mat[0]);
     295       56856 :             if (ret)
     296           0 :                 return ret;
     297       56856 :             c->prev_dc[0][mb_x * 2 + i] = c->dc_cache[j][LEFT];
     298             : 
     299       56856 :             ff_mss34_dct_put(out + xpos * 8, c->pic->linesize[0],
     300       56856 :                              c->block);
     301             :         }
     302       28428 :         out += 8 * c->pic->linesize[0];
     303             :     }
     304             : 
     305       42642 :     for (i = 1; i < 3; i++) {
     306       28428 :         c->dc_cache[i + 1][TOP_LEFT] = c->dc_cache[i + 1][TOP];
     307       28428 :         c->dc_cache[i + 1][TOP]      = c->prev_dc[i][mb_x];
     308       28428 :         ret = mss4_decode_dct(gb, c->dc_vlc + 1, c->ac_vlc + 1,
     309       28428 :                               c->block, c->dc_cache[i + 1], mb_x, mb_y,
     310       28428 :                               c->quant_mat[1]);
     311       28428 :         if (ret)
     312           0 :             return ret;
     313       28428 :         c->prev_dc[i][mb_x] = c->dc_cache[i + 1][LEFT];
     314             : 
     315       28428 :         ff_mss34_dct_put(c->imgbuf[i], 8, c->block);
     316       28428 :         out = dst[i] + mb_x * 16;
     317             :         // Since the DCT block is coded as YUV420 and the whole frame as YUV444,
     318             :         // we need to scale chroma.
     319      483276 :         for (j = 0; j < 16; j++) {
     320     4093632 :             for (k = 0; k < 8; k++)
     321     3638784 :                 AV_WN16A(out + k * 2, c->imgbuf[i][k + (j & ~1) * 4] * 0x101);
     322      454848 :             out += c->pic->linesize[i];
     323             :         }
     324             :     }
     325             : 
     326       14214 :     return 0;
     327             : }
     328             : 
     329      281245 : static void read_vec_pos(GetBitContext *gb, int *vec_pos, int *sel_flag,
     330             :                          int *sel_len, int *prev)
     331             : {
     332      281245 :     int i, y_flag = 0;
     333             : 
     334     1124980 :     for (i = 2; i >= 0; i--) {
     335      843735 :         if (!sel_flag[i]) {
     336      192630 :             vec_pos[i] = 0;
     337      192630 :             continue;
     338             :         }
     339      651105 :         if ((!i && !y_flag) || get_bits1(gb)) {
     340      554066 :             if (sel_len[i] > 0) {
     341      549560 :                 int pval = prev[i];
     342      549560 :                 vec_pos[i] = get_bits(gb, sel_len[i]);
     343      549560 :                 if (vec_pos[i] >= pval)
     344      297455 :                     vec_pos[i]++;
     345             :             } else {
     346        4506 :                 vec_pos[i] = !prev[i];
     347             :             }
     348      554066 :             y_flag = 1;
     349             :         } else {
     350       97039 :             vec_pos[i] = prev[i];
     351             :         }
     352             :     }
     353      281245 : }
     354             : 
     355     8739072 : static int get_value_cached(GetBitContext *gb, int vec_pos, uint8_t *vec,
     356             :                             int vec_size, int component, int shift, int *prev)
     357             : {
     358     8739072 :     if (vec_pos < vec_size)
     359     8442194 :         return vec[vec_pos];
     360      296878 :     if (!get_bits1(gb))
     361       46525 :         return prev[component];
     362      250353 :     prev[component] = get_bits(gb, 8 - shift) << shift;
     363      250353 :     return prev[component];
     364             : }
     365             : 
     366             : #define MKVAL(vals)  ((vals)[0] | ((vals)[1] << 3) | ((vals)[2] << 6))
     367             : 
     368             : /* Image mode - the hardest to comprehend MSS4 coding mode.
     369             :  *
     370             :  * In this mode all three 16x16 blocks are coded together with a method
     371             :  * remotely similar to the methods employed in MSS1-MSS3.
     372             :  * The idea is that every component has a vector of 1-4 most common symbols
     373             :  * and an escape mode for reading new value from the bitstream. Decoding
     374             :  * consists of retrieving pixel values from the vector or reading new ones
     375             :  * from the bitstream; depending on flags read from the bitstream, these vector
     376             :  * positions can be updated or reused from the state of the previous line
     377             :  * or previous pixel.
     378             :  */
     379       11379 : static int mss4_decode_image_block(MSS4Context *ctx, GetBitContext *gb,
     380             :                                    uint8_t *picdst[3], int mb_x, int mb_y)
     381             : {
     382             :     uint8_t vec[3][4];
     383             :     int     vec_len[3];
     384             :     int     sel_len[3], sel_flag[3];
     385             :     int     i, j, k, mode, split;
     386       11379 :     int     prev_vec1 = 0, prev_split = 0;
     387       11379 :     int     vals[3] = { 0 };
     388       11379 :     int     prev_pix[3] = { 0 };
     389       11379 :     int     prev_mode[16] = { 0 };
     390             :     uint8_t *dst[3];
     391             : 
     392       11379 :     const int val_shift = ctx->quality == 100 ? 0 : 2;
     393             : 
     394       45516 :     for (i = 0; i < 3; i++)
     395       34137 :         dst[i] = ctx->imgbuf[i];
     396             : 
     397       45516 :     for (i = 0; i < 3; i++) {
     398       34137 :         vec_len[i] = vec_len_syms[!!i][get_unary(gb, 0, 3)];
     399      129439 :         for (j = 0; j < vec_len[i]; j++) {
     400       95302 :             vec[i][j]  = get_coeff(gb, &ctx->vec_entry_vlc[!!i]);
     401       95302 :             vec[i][j] += ctx->prev_vec[i][j];
     402       95302 :             ctx->prev_vec[i][j] = vec[i][j];
     403             :         }
     404       34137 :         sel_flag[i] = vec_len[i] > 1;
     405       34137 :         sel_len[i]  = vec_len[i] > 2 ? vec_len[i] - 2 : 0;
     406             :     }
     407             : 
     408      193443 :     for (j = 0; j < 16; j++) {
     409      182064 :         if (get_bits1(gb)) {
     410       56004 :             split = 0;
     411       56004 :             if (get_bits1(gb)) {
     412       35860 :                 prev_mode[0] = 0;
     413       35860 :                 vals[0] = vals[1] = vals[2] = 0;
     414       35860 :                 mode = 2;
     415             :             } else {
     416       20144 :                 mode = get_bits1(gb);
     417       20144 :                 if (mode)
     418        3817 :                     split = get_bits(gb, 4);
     419             :             }
     420      952068 :             for (i = 0; i < 16; i++) {
     421      896064 :                 if (mode <= 1) {
     422      322304 :                     vals[0] =  prev_mode[i]       & 7;
     423      322304 :                     vals[1] = (prev_mode[i] >> 3) & 7;
     424      322304 :                     vals[2] =  prev_mode[i] >> 6;
     425      322304 :                     if (mode == 1 && i == split) {
     426        3817 :                         read_vec_pos(gb, vals, sel_flag, sel_len, vals);
     427             :                     }
     428      573760 :                 } else if (mode == 2) {
     429      573760 :                     if (get_bits1(gb))
     430      261389 :                         read_vec_pos(gb, vals, sel_flag, sel_len, vals);
     431             :                 }
     432     3584256 :                 for (k = 0; k < 3; k++)
     433     2688192 :                     *dst[k]++ = get_value_cached(gb, vals[k], vec[k],
     434             :                                                  vec_len[k], k,
     435             :                                                  val_shift, prev_pix);
     436      896064 :                 prev_mode[i] = MKVAL(vals);
     437             :             }
     438             :         } else {
     439      126060 :             if (get_bits1(gb)) {
     440       21425 :                 split = get_bits(gb, 4);
     441       21425 :                 if (split >= prev_split)
     442       15525 :                     split++;
     443       21425 :                 prev_split = split;
     444             :             } else {
     445      104635 :                 split = prev_split;
     446             :             }
     447      126060 :             if (split) {
     448      109261 :                 vals[0] =  prev_mode[0]       & 7;
     449      109261 :                 vals[1] = (prev_mode[0] >> 3) & 7;
     450      109261 :                 vals[2] =  prev_mode[0] >> 6;
     451      437044 :                 for (i = 0; i < 3; i++) {
     452     5442705 :                     for (k = 0; k < split; k++) {
     453     5114922 :                         *dst[i]++ = get_value_cached(gb, vals[i], vec[i],
     454             :                                                      vec_len[i], i, val_shift,
     455             :                                                      prev_pix);
     456     5114922 :                         prev_mode[k] = MKVAL(vals);
     457             :                     }
     458             :                 }
     459             :             }
     460             : 
     461      126060 :             if (split != 16) {
     462       22314 :                 vals[0] =  prev_vec1       & 7;
     463       22314 :                 vals[1] = (prev_vec1 >> 3) & 7;
     464       22314 :                 vals[2] =  prev_vec1 >> 6;
     465       22314 :                 if (get_bits1(gb)) {
     466       16039 :                     read_vec_pos(gb, vals, sel_flag, sel_len, vals);
     467       16039 :                     prev_vec1 = MKVAL(vals);
     468             :                 }
     469       89256 :                 for (i = 0; i < 3; i++) {
     470     1002900 :                     for (k = 0; k < 16 - split; k++) {
     471      935958 :                         *dst[i]++ = get_value_cached(gb, vals[i], vec[i],
     472             :                                                      vec_len[i], i, val_shift,
     473             :                                                      prev_pix);
     474      935958 :                         prev_mode[split + k] = MKVAL(vals);
     475             :                     }
     476             :                 }
     477             :             }
     478             :         }
     479             :     }
     480             : 
     481       45516 :     for (i = 0; i < 3; i++)
     482      580329 :         for (j = 0; j < 16; j++)
     483      546192 :             memcpy(picdst[i] + mb_x * 16 + j * ctx->pic->linesize[i],
     484      546192 :                    ctx->imgbuf[i] + j * 16, 16);
     485             : 
     486       11379 :     return 0;
     487             : }
     488             : 
     489      175050 : static inline void mss4_update_dc_cache(MSS4Context *c, int mb_x)
     490             : {
     491             :     int i;
     492             : 
     493      175050 :     c->dc_cache[0][TOP]  = c->prev_dc[0][mb_x * 2 + 1];
     494      175050 :     c->dc_cache[0][LEFT] = 0;
     495      175050 :     c->dc_cache[1][TOP]  = 0;
     496      175050 :     c->dc_cache[1][LEFT] = 0;
     497             : 
     498      525150 :     for (i = 0; i < 2; i++)
     499      350100 :         c->prev_dc[0][mb_x * 2 + i] = 0;
     500             : 
     501      525150 :     for (i = 1; i < 3; i++) {
     502      350100 :         c->dc_cache[i + 1][TOP]  = c->prev_dc[i][mb_x];
     503      350100 :         c->dc_cache[i + 1][LEFT] = 0;
     504      350100 :         c->prev_dc[i][mb_x]      = 0;
     505             :     }
     506      175050 : }
     507             : 
     508         145 : static int mss4_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     509             :                              AVPacket *avpkt)
     510             : {
     511         145 :     const uint8_t *buf = avpkt->data;
     512         145 :     int buf_size = avpkt->size;
     513         145 :     MSS4Context *c = avctx->priv_data;
     514             :     GetBitContext gb;
     515             :     GetByteContext bc;
     516             :     uint8_t *dst[3];
     517             :     int width, height, quality, frame_type;
     518             :     int x, y, i, mb_width, mb_height, blk_type;
     519             :     int ret;
     520             : 
     521         145 :     if (buf_size < HEADER_SIZE) {
     522           0 :         av_log(avctx, AV_LOG_ERROR,
     523             :                "Frame should have at least %d bytes, got %d instead\n",
     524             :                HEADER_SIZE, buf_size);
     525           0 :         return AVERROR_INVALIDDATA;
     526             :     }
     527             : 
     528         145 :     bytestream2_init(&bc, buf, buf_size);
     529         145 :     width      = bytestream2_get_be16(&bc);
     530         145 :     height     = bytestream2_get_be16(&bc);
     531         145 :     bytestream2_skip(&bc, 2);
     532         145 :     quality    = bytestream2_get_byte(&bc);
     533         145 :     frame_type = bytestream2_get_byte(&bc);
     534             : 
     535         290 :     if (width > avctx->width ||
     536         145 :         height != avctx->height) {
     537           0 :         av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d\n",
     538             :                width, height);
     539           0 :         return AVERROR_INVALIDDATA;
     540             :     }
     541         145 :     if (quality < 1 || quality > 100) {
     542           0 :         av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);
     543           0 :         return AVERROR_INVALIDDATA;
     544             :     }
     545         145 :     if ((frame_type & ~3) || frame_type == 3) {
     546           0 :         av_log(avctx, AV_LOG_ERROR, "Invalid frame type %d\n", frame_type);
     547           0 :         return AVERROR_INVALIDDATA;
     548             :     }
     549             : 
     550         145 :     if (frame_type != SKIP_FRAME && !bytestream2_get_bytes_left(&bc)) {
     551           0 :         av_log(avctx, AV_LOG_ERROR,
     552             :                "Empty frame found but it is not a skip frame.\n");
     553           0 :         return AVERROR_INVALIDDATA;
     554             :     }
     555             : 
     556         145 :     if ((ret = ff_reget_buffer(avctx, c->pic)) < 0)
     557           0 :         return ret;
     558         145 :     c->pic->key_frame = (frame_type == INTRA_FRAME);
     559         145 :     c->pic->pict_type = (frame_type == INTRA_FRAME) ? AV_PICTURE_TYPE_I
     560         145 :                                                    : AV_PICTURE_TYPE_P;
     561         145 :     if (frame_type == SKIP_FRAME) {
     562          98 :         *got_frame      = 1;
     563          98 :         if ((ret = av_frame_ref(data, c->pic)) < 0)
     564           0 :             return ret;
     565             : 
     566          98 :         return buf_size;
     567             :     }
     568             : 
     569          47 :     if (c->quality != quality) {
     570           2 :         c->quality = quality;
     571           6 :         for (i = 0; i < 2; i++)
     572           4 :             ff_mss34_gen_quant_mat(c->quant_mat[i], quality, !i);
     573             :     }
     574             : 
     575          47 :     if ((ret = init_get_bits8(&gb, buf + HEADER_SIZE, buf_size - HEADER_SIZE)) < 0)
     576           0 :         return ret;
     577             : 
     578          47 :     mb_width  = FFALIGN(width,  16) >> 4;
     579          47 :     mb_height = FFALIGN(height, 16) >> 4;
     580          47 :     dst[0] = c->pic->data[0];
     581          47 :     dst[1] = c->pic->data[1];
     582          47 :     dst[2] = c->pic->data[2];
     583             : 
     584          47 :     memset(c->prev_vec, 0, sizeof(c->prev_vec));
     585        2519 :     for (y = 0; y < mb_height; y++) {
     586        2472 :         memset(c->dc_cache, 0, sizeof(c->dc_cache));
     587      191736 :         for (x = 0; x < mb_width; x++) {
     588      189264 :             blk_type = decode012(&gb);
     589      189264 :             switch (blk_type) {
     590       14214 :             case DCT_BLOCK:
     591       14214 :                 if (mss4_decode_dct_block(c, &gb, dst, x, y) < 0) {
     592           0 :                     av_log(avctx, AV_LOG_ERROR,
     593             :                            "Error decoding DCT block %d,%d\n",
     594             :                            x, y);
     595           0 :                     return AVERROR_INVALIDDATA;
     596             :                 }
     597       14214 :                 break;
     598       11379 :             case IMAGE_BLOCK:
     599       11379 :                 if (mss4_decode_image_block(c, &gb, dst, x, y) < 0) {
     600           0 :                     av_log(avctx, AV_LOG_ERROR,
     601             :                            "Error decoding VQ block %d,%d\n",
     602             :                            x, y);
     603           0 :                     return AVERROR_INVALIDDATA;
     604             :                 }
     605       11379 :                 break;
     606      163671 :             case SKIP_BLOCK:
     607      163671 :                 if (frame_type == INTRA_FRAME) {
     608           0 :                     av_log(avctx, AV_LOG_ERROR, "Skip block in intra frame\n");
     609           0 :                     return AVERROR_INVALIDDATA;
     610             :                 }
     611      163671 :                 break;
     612             :             }
     613      189264 :             if (blk_type != DCT_BLOCK)
     614      175050 :                 mss4_update_dc_cache(c, x);
     615             :         }
     616        2472 :         dst[0] += c->pic->linesize[0] * 16;
     617        2472 :         dst[1] += c->pic->linesize[1] * 16;
     618        2472 :         dst[2] += c->pic->linesize[2] * 16;
     619             :     }
     620             : 
     621          47 :     if ((ret = av_frame_ref(data, c->pic)) < 0)
     622           0 :         return ret;
     623             : 
     624          47 :     *got_frame      = 1;
     625             : 
     626          47 :     return buf_size;
     627             : }
     628             : 
     629           4 : static av_cold int mss4_decode_end(AVCodecContext *avctx)
     630             : {
     631           4 :     MSS4Context * const c = avctx->priv_data;
     632             :     int i;
     633             : 
     634           4 :     av_frame_free(&c->pic);
     635          16 :     for (i = 0; i < 3; i++)
     636          12 :         av_freep(&c->prev_dc[i]);
     637           4 :     mss4_free_vlcs(c);
     638             : 
     639           4 :     return 0;
     640             : }
     641             : 
     642           4 : static av_cold int mss4_decode_init(AVCodecContext *avctx)
     643             : {
     644           4 :     MSS4Context * const c = avctx->priv_data;
     645             :     int i;
     646             : 
     647           4 :     if (mss4_init_vlcs(c)) {
     648           0 :         av_log(avctx, AV_LOG_ERROR, "Cannot initialise VLCs\n");
     649           0 :         mss4_free_vlcs(c);
     650           0 :         return AVERROR(ENOMEM);
     651             :     }
     652          16 :     for (i = 0; i < 3; i++) {
     653          12 :         c->dc_stride[i] = FFALIGN(avctx->width, 16) >> (2 + !!i);
     654          12 :         c->prev_dc[i]   = av_malloc_array(c->dc_stride[i], sizeof(**c->prev_dc));
     655          12 :         if (!c->prev_dc[i]) {
     656           0 :             av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
     657           0 :             mss4_free_vlcs(c);
     658           0 :             return AVERROR(ENOMEM);
     659             :         }
     660             :     }
     661             : 
     662           4 :     c->pic = av_frame_alloc();
     663           4 :     if (!c->pic) {
     664           0 :         mss4_decode_end(avctx);
     665           0 :         return AVERROR(ENOMEM);
     666             :     }
     667             : 
     668           4 :     avctx->pix_fmt     = AV_PIX_FMT_YUV444P;
     669             : 
     670           4 :     return 0;
     671             : }
     672             : 
     673             : AVCodec ff_mts2_decoder = {
     674             :     .name           = "mts2",
     675             :     .long_name      = NULL_IF_CONFIG_SMALL("MS Expression Encoder Screen"),
     676             :     .type           = AVMEDIA_TYPE_VIDEO,
     677             :     .id             = AV_CODEC_ID_MTS2,
     678             :     .priv_data_size = sizeof(MSS4Context),
     679             :     .init           = mss4_decode_init,
     680             :     .close          = mss4_decode_end,
     681             :     .decode         = mss4_decode_frame,
     682             :     .capabilities   = AV_CODEC_CAP_DR1,
     683             : };

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