LCOV - code coverage report
Current view: top level - libavcodec - bmvvideo.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 115 158 72.8 %
Date: 2017-12-13 18:07:29 Functions: 3 3 100.0 %

          Line data    Source code
       1             : /*
       2             :  * Discworld II BMV video decoder
       3             :  * Copyright (c) 2011 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             : #include "libavutil/avassert.h"
      23             : #include "libavutil/common.h"
      24             : 
      25             : #include "avcodec.h"
      26             : #include "bytestream.h"
      27             : #include "internal.h"
      28             : 
      29             : enum BMVFlags{
      30             :     BMV_NOP = 0,
      31             :     BMV_END,
      32             :     BMV_DELTA,
      33             :     BMV_INTRA,
      34             : 
      35             :     BMV_SCROLL  = 0x04,
      36             :     BMV_PALETTE = 0x08,
      37             :     BMV_COMMAND = 0x10,
      38             :     BMV_AUDIO   = 0x20,
      39             :     BMV_EXT     = 0x40,
      40             :     BMV_PRINT   = 0x80
      41             : };
      42             : 
      43             : #define SCREEN_WIDE 640
      44             : #define SCREEN_HIGH 429
      45             : 
      46             : typedef struct BMVDecContext {
      47             :     AVCodecContext *avctx;
      48             : 
      49             :     uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
      50             :     uint32_t pal[256];
      51             :     const uint8_t *stream;
      52             : } BMVDecContext;
      53             : 
      54             : #define NEXT_BYTE(v) (v) = forward ? (v) + 1 : (v) - 1;
      55             : 
      56          21 : static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
      57             : {
      58          21 :     unsigned val, saved_val = 0;
      59          21 :     int tmplen = src_len;
      60          21 :     const uint8_t *src, *source_end = source + src_len;
      61          21 :     uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
      62             :     uint8_t *dst, *dst_end;
      63             :     int len, mask;
      64          21 :     int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
      65             :     int read_two_nibbles, flag;
      66             :     int advance_mode;
      67          21 :     int mode = 0;
      68             :     int i;
      69             : 
      70          21 :     if (src_len <= 0)
      71           0 :         return AVERROR_INVALIDDATA;
      72             : 
      73          21 :     if (forward) {
      74          21 :         src = source;
      75          21 :         dst = frame;
      76          21 :         dst_end = frame_end;
      77             :     } else {
      78           0 :         src = source + src_len - 1;
      79           0 :         dst = frame_end - 1;
      80           0 :         dst_end = frame - 1;
      81             :     }
      82      783652 :     for (;;) {
      83      783673 :         int shift = 0;
      84      783673 :         flag = 0;
      85             : 
      86             :         /* The mode/len decoding is a bit strange:
      87             :          * values are coded as variable-length codes with nibble units,
      88             :          * code end is signalled by two top bits in the nibble being nonzero.
      89             :          * And since data is bytepacked and we read two nibbles at a time,
      90             :          * we may get a nibble belonging to the next code.
      91             :          * Hence this convoluted loop.
      92             :          */
      93      783673 :         if (!mode || (tmplen == 4)) {
      94      391887 :             if (src < source || src >= source_end)
      95           0 :                 return AVERROR_INVALIDDATA;
      96      391887 :             val = *src;
      97      391887 :             read_two_nibbles = 1;
      98             :         } else {
      99      391786 :             val = saved_val;
     100      391786 :             read_two_nibbles = 0;
     101             :         }
     102      783673 :         if (!(val & 0xC)) {
     103             :             for (;;) {
     104       76713 :                 if(shift>22)
     105           0 :                     return -1;
     106       73874 :                 if (!read_two_nibbles) {
     107       38323 :                     if (src < source || src >= source_end)
     108           0 :                         return AVERROR_INVALIDDATA;
     109       38323 :                     shift += 2;
     110       38323 :                     val |= (unsigned)*src << shift;
     111       38323 :                     if (*src & 0xC)
     112       35465 :                         break;
     113             :                 }
     114             :                 // two upper bits of the nibble is zero,
     115             :                 // so shift top nibble value down into their place
     116       38409 :                 read_two_nibbles = 0;
     117       38409 :                 shift += 2;
     118       38409 :                 mask = (1 << shift) - 1;
     119       38409 :                 val = ((val >> 2) & ~mask) | (val & mask);
     120       38409 :                 NEXT_BYTE(src);
     121       38409 :                 if ((val & (0xC << shift))) {
     122       35570 :                     flag = 1;
     123       35570 :                     break;
     124             :                 }
     125             :             }
     126      712638 :         } else if (mode) {
     127      712627 :             flag = tmplen != 4;
     128             :         }
     129      783673 :         if (flag) {
     130      391872 :             tmplen = 4;
     131             :         } else {
     132      391801 :             saved_val = val >> (4 + shift);
     133      391801 :             tmplen = 0;
     134      391801 :             val &= (1 << (shift + 4)) - 1;
     135      391801 :             NEXT_BYTE(src);
     136             :         }
     137      783673 :         advance_mode = val & 1;
     138      783673 :         len = (val >> 1) - 1;
     139      783673 :         av_assert0(len>0);
     140      783673 :         mode += 1 + advance_mode;
     141      783673 :         if (mode >= 4)
     142      380507 :             mode -= 3;
     143      783673 :         if (len <= 0 || FFABS(dst_end - dst) < len)
     144           0 :             return AVERROR_INVALIDDATA;
     145      783673 :         switch (mode) {
     146      207200 :         case 1:
     147      207200 :             if (forward) {
     148      414400 :                 if (dst - frame + SCREEN_WIDE < frame_off ||
     149      414400 :                         dst - frame + SCREEN_WIDE + frame_off < 0 ||
     150      414400 :                         frame_end - dst < frame_off + len ||
     151      207200 :                         frame_end - dst < len)
     152           0 :                     return AVERROR_INVALIDDATA;
     153     4179410 :                 for (i = 0; i < len; i++)
     154     3972210 :                     dst[i] = dst[frame_off + i];
     155      207200 :                 dst += len;
     156             :             } else {
     157           0 :                 dst -= len;
     158           0 :                 if (dst - frame + SCREEN_WIDE < frame_off ||
     159           0 :                         dst - frame + SCREEN_WIDE + frame_off < 0 ||
     160           0 :                         frame_end - dst < frame_off + len ||
     161           0 :                         frame_end - dst < len)
     162           0 :                     return AVERROR_INVALIDDATA;
     163           0 :                 for (i = len - 1; i >= 0; i--)
     164           0 :                     dst[i] = dst[frame_off + i];
     165             :             }
     166      207200 :             break;
     167      312625 :         case 2:
     168      312625 :             if (forward) {
     169      312625 :                 if (source + src_len - src < len)
     170           0 :                     return AVERROR_INVALIDDATA;
     171      312625 :                 memcpy(dst, src, len);
     172      312625 :                 dst += len;
     173      312625 :                 src += len;
     174             :             } else {
     175           0 :                 if (src - source < len)
     176           0 :                     return AVERROR_INVALIDDATA;
     177           0 :                 dst -= len;
     178           0 :                 src -= len;
     179           0 :                 memcpy(dst, src, len);
     180             :             }
     181      312625 :             break;
     182      263848 :         case 3:
     183      263848 :             val = forward ? dst[-1] : dst[1];
     184      263848 :             if (forward) {
     185      263848 :                 memset(dst, val, len);
     186      263848 :                 dst += len;
     187             :             } else {
     188           0 :                 dst -= len;
     189           0 :                 memset(dst, val, len);
     190             :             }
     191      263848 :             break;
     192             :         }
     193      783673 :         if (dst == dst_end)
     194          21 :             return 0;
     195             :     }
     196             : }
     197             : 
     198          21 : static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     199             :                         AVPacket *pkt)
     200             : {
     201          21 :     BMVDecContext * const c = avctx->priv_data;
     202          21 :     AVFrame *frame = data;
     203             :     int type, scr_off;
     204             :     int i, ret;
     205             :     uint8_t *srcptr, *outptr;
     206             : 
     207          21 :     c->stream = pkt->data;
     208          21 :     type = bytestream_get_byte(&c->stream);
     209          21 :     if (type & BMV_AUDIO) {
     210          21 :         int blobs = bytestream_get_byte(&c->stream);
     211          21 :         if (pkt->size < blobs * 65 + 2) {
     212           0 :             av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
     213           0 :             return AVERROR_INVALIDDATA;
     214             :         }
     215          21 :         c->stream += blobs * 65;
     216             :     }
     217          21 :     if (type & BMV_COMMAND) {
     218           0 :         int command_size = (type & BMV_PRINT) ? 8 : 10;
     219           0 :         if (c->stream - pkt->data + command_size > pkt->size) {
     220           0 :             av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
     221           0 :             return AVERROR_INVALIDDATA;
     222             :         }
     223           0 :         c->stream += command_size;
     224             :     }
     225          21 :     if (type & BMV_PALETTE) {
     226           1 :         if (c->stream - pkt->data > pkt->size - 768) {
     227           0 :             av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
     228           0 :             return AVERROR_INVALIDDATA;
     229             :         }
     230         257 :         for (i = 0; i < 256; i++)
     231         256 :             c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream);
     232             :     }
     233          21 :     if (type & BMV_SCROLL) {
     234           0 :         if (c->stream - pkt->data > pkt->size - 2) {
     235           0 :             av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
     236           0 :             return AVERROR_INVALIDDATA;
     237             :         }
     238           0 :         scr_off = (int16_t)bytestream_get_le16(&c->stream);
     239          21 :     } else if ((type & BMV_INTRA) == BMV_INTRA) {
     240          11 :         scr_off = -640;
     241             :     } else {
     242          10 :         scr_off = 0;
     243             :     }
     244             : 
     245          21 :     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
     246           0 :         return ret;
     247             : 
     248          21 :     if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
     249           0 :         av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
     250           0 :         return AVERROR_INVALIDDATA;
     251             :     }
     252             : 
     253          21 :     memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
     254          21 :     frame->palette_has_changed = type & BMV_PALETTE;
     255             : 
     256          21 :     outptr = frame->data[0];
     257          21 :     srcptr = c->frame;
     258             : 
     259        9030 :     for (i = 0; i < avctx->height; i++) {
     260        9009 :         memcpy(outptr, srcptr, avctx->width);
     261        9009 :         srcptr += avctx->width;
     262        9009 :         outptr += frame->linesize[0];
     263             :     }
     264             : 
     265          21 :     *got_frame = 1;
     266             : 
     267             :     /* always report that the buffer was completely consumed */
     268          21 :     return pkt->size;
     269             : }
     270             : 
     271           3 : static av_cold int decode_init(AVCodecContext *avctx)
     272             : {
     273           3 :     BMVDecContext * const c = avctx->priv_data;
     274             : 
     275           3 :     c->avctx = avctx;
     276           3 :     avctx->pix_fmt = AV_PIX_FMT_PAL8;
     277             : 
     278           3 :     if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) {
     279           0 :         av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height);
     280           0 :         return AVERROR_INVALIDDATA;
     281             :     }
     282             : 
     283           3 :     c->frame = c->frame_base + 640;
     284             : 
     285           3 :     return 0;
     286             : }
     287             : 
     288             : AVCodec ff_bmv_video_decoder = {
     289             :     .name           = "bmv_video",
     290             :     .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
     291             :     .type           = AVMEDIA_TYPE_VIDEO,
     292             :     .id             = AV_CODEC_ID_BMV_VIDEO,
     293             :     .priv_data_size = sizeof(BMVDecContext),
     294             :     .init           = decode_init,
     295             :     .decode         = decode_frame,
     296             :     .capabilities   = AV_CODEC_CAP_DR1,
     297             :     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
     298             : };

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