libavcodec/cdgraphics.c

   1 /*
   2  * CD Graphics Video Decoder
   3  * Copyright (c) 2009 Michael Tison
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "avcodec.h"
  23 #include "bytestream.h"
  24 #include "internal.h"
  25
  26 /**
  27  * @file
  28  * @brief CD Graphics Video Decoder
  29  * @author Michael Tison
  30  * @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
  31  * @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
  32  */
  33
  34 /// default screen sizes
  35 #define CDG_FULL_WIDTH           300
  36 #define CDG_FULL_HEIGHT          216
  37 #define CDG_DISPLAY_WIDTH        294
  38 #define CDG_DISPLAY_HEIGHT       204
  39 #define CDG_BORDER_WIDTH           6
  40 #define CDG_BORDER_HEIGHT         12
  41
  42 /// masks
  43 #define CDG_COMMAND             0x09
  44 #define CDG_MASK                0x3F
  45
  46 /// instruction codes
  47 #define CDG_INST_MEMORY_PRESET     1
  48 #define CDG_INST_BORDER_PRESET     2
  49 #define CDG_INST_TILE_BLOCK        6
  50 #define CDG_INST_SCROLL_PRESET    20
  51 #define CDG_INST_SCROLL_COPY      24
  52 #define CDG_INST_LOAD_PAL_LO      30
  53 #define CDG_INST_LOAD_PAL_HIGH    31
  54 #define CDG_INST_TILE_BLOCK_XOR   38
  55
  56 /// data sizes
  57 #define CDG_PACKET_SIZE           24
  58 #define CDG_DATA_SIZE             16
  59 #define CDG_TILE_HEIGHT           12
  60 #define CDG_TILE_WIDTH             6
  61 #define CDG_MINIMUM_PKT_SIZE       6
  62 #define CDG_MINIMUM_SCROLL_SIZE    3
  63 #define CDG_HEADER_SIZE            8
  64 #define CDG_PALETTE_SIZE          16
  65
  66 typedef struct CDGraphicsContext {
  67     AVFrame frame;
  68     int hscroll;
  69     int vscroll;
  70 } CDGraphicsContext;
  71
  72 static void cdg_init_frame(AVFrame *frame)
  73 {
  74     avcodec_get_frame_defaults(frame);
  75     frame->reference = 3;
  76     frame->buffer_hints = FF_BUFFER_HINTS_VALID    |
  77                           FF_BUFFER_HINTS_READABLE |
  78                           FF_BUFFER_HINTS_PRESERVE |
  79                           FF_BUFFER_HINTS_REUSABLE;
  80 }
  81
  82 static av_cold int cdg_decode_init(AVCodecContext *avctx)
  83 {
  84     CDGraphicsContext *cc = avctx->priv_data;
  85
  86     cdg_init_frame(&cc->frame);
  87
  88     avctx->width   = CDG_FULL_WIDTH;
  89     avctx->height  = CDG_FULL_HEIGHT;
  90     avctx->pix_fmt = AV_PIX_FMT_PAL8;
  91
  92     return 0;
  93 }
  94
  95 static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
  96 {
  97     int y;
  98     int lsize    = cc->frame.linesize[0];
  99     uint8_t *buf = cc->frame.data[0];
 100     int color    = data[0] & 0x0F;
 101
 102     if (!(data[1] & 0x0F)) {
 103         /// fill the top and bottom borders
 104         memset(buf, color, CDG_BORDER_HEIGHT * lsize);
 105         memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
 106                color, CDG_BORDER_HEIGHT * lsize);
 107
 108         /// fill the side borders
 109         for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
 110             memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
 111             memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
 112                    color, CDG_BORDER_WIDTH);
 113         }
 114     }
 115 }
 116
 117 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
 118 {
 119     uint8_t r, g, b;
 120     uint16_t color;
 121     int i;
 122     int array_offset  = low ? 0 : 8;
 123     uint32_t *palette = (uint32_t *) cc->frame.data[1];
 124
 125     for (i = 0; i < 8; i++) {
 126         color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
 127         r = ((color >> 8) & 0x000F) * 17;
 128         g = ((color >> 4) & 0x000F) * 17;
 129         b = ((color     ) & 0x000F) * 17;
 130         palette[i + array_offset] = r << 16 | g << 8 | b;
 131     }
 132     cc->frame.palette_has_changed = 1;
 133 }
 134
 135 static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
 136 {
 137     unsigned ci, ri;
 138     int color;
 139     int x, y;
 140     int ai;
 141     int stride   = cc->frame.linesize[0];
 142     uint8_t *buf = cc->frame.data[0];
 143
 144     ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
 145     ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;
 146
 147     if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
 148         return AVERROR(EINVAL);
 149     if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
 150         return AVERROR(EINVAL);
 151
 152     for (y = 0; y < CDG_TILE_HEIGHT; y++) {
 153         for (x = 0; x < CDG_TILE_WIDTH; x++) {
 154             if (!((data[4 + y] >> (5 - x)) & 0x01))
 155                 color = data[0] & 0x0F;
 156             else
 157                 color = data[1] & 0x0F;
 158
 159             ai = ci + x + (stride * (ri + y));
 160             if (b)
 161                 color ^= buf[ai];
 162             buf[ai] = color;
 163         }
 164     }
 165
 166     return 0;
 167 }
 168
 169 #define UP    2
 170 #define DOWN  1
 171 #define LEFT  2
 172 #define RIGHT 1
 173
 174 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
 175                               int in_tl_x, int in_tl_y, uint8_t *in,
 176                               int w, int h, int stride)
 177 {
 178     int y;
 179
 180     in  += in_tl_x  + in_tl_y  * stride;
 181     out += out_tl_x + out_tl_y * stride;
 182     for (y = 0; y < h; y++)
 183         memcpy(out + y * stride, in + y * stride, w);
 184 }
 185
 186 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
 187                                  int color, int w, int h, int stride)
 188 {
 189     int y;
 190
 191     for (y = tl_y; y < tl_y + h; y++)
 192         memset(out + tl_x + y * stride, color, w);
 193 }
 194
 195 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
 196                              int in_tl_x, int in_tl_y, uint8_t *in,
 197                              int color, int w, int h, int stride, int roll)
 198 {
 199     if (roll) {
 200         cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
 201                           in, w, h, stride);
 202     } else {
 203         cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
 204     }
 205 }
 206
 207 static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
 208                        AVFrame *new_frame, int roll_over)
 209 {
 210     int color;
 211     int hscmd, h_off, hinc, vscmd, v_off, vinc;
 212     int y;
 213     int stride   = cc->frame.linesize[0];
 214     uint8_t *in  = cc->frame.data[0];
 215     uint8_t *out = new_frame->data[0];
 216
 217     color =  data[0] & 0x0F;
 218     hscmd = (data[1] & 0x30) >> 4;
 219     vscmd = (data[2] & 0x30) >> 4;
 220
 221     h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
 222     v_off =  FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
 223
 224     /// find the difference and save the offset for cdg_tile_block usage
 225     hinc = h_off - cc->hscroll;
 226     vinc = v_off - cc->vscroll;
 227     cc->hscroll = h_off;
 228     cc->vscroll = v_off;
 229
 230     if (vscmd == UP)
 231         vinc -= 12;
 232     if (vscmd == DOWN)
 233         vinc += 12;
 234     if (hscmd == LEFT)
 235         hinc -= 6;
 236     if (hscmd == RIGHT)
 237         hinc += 6;
 238
 239     if (!hinc && !vinc)
 240         return;
 241
 242     memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);
 243
 244     for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
 245         memcpy(out + FFMAX(0, hinc) + stride * y,
 246                in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
 247                FFMIN(stride + hinc, stride));
 248
 249     if (vinc > 0)
 250         cdg_fill_wrapper(0, 0, out,
 251                          0, CDG_FULL_HEIGHT - vinc, in, color,
 252                          stride, vinc, stride, roll_over);
 253     else if (vinc < 0)
 254         cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
 255                          0, 0, in, color,
 256                          stride, -1 * vinc, stride, roll_over);
 257
 258     if (hinc > 0)
 259         cdg_fill_wrapper(0, 0, out,
 260                          CDG_FULL_WIDTH - hinc, 0, in, color,
 261                          hinc, CDG_FULL_HEIGHT, stride, roll_over);
 262     else if (hinc < 0)
 263         cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
 264                          0, 0, in, color,
 265                          -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
 266
 267 }
 268
 269 static int cdg_decode_frame(AVCodecContext *avctx,
 270                             void *data, int *got_frame, AVPacket *avpkt)
 271 {
 272     const uint8_t *buf = avpkt->data;
 273     int buf_size       = avpkt->size;
 274     int ret;
 275     uint8_t command, inst;
 276     uint8_t cdg_data[CDG_DATA_SIZE];
 277     AVFrame new_frame;
 278     CDGraphicsContext *cc = avctx->priv_data;
 279
 280     if (buf_size < CDG_MINIMUM_PKT_SIZE) {
 281         av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
 282         return AVERROR(EINVAL);
 283     }
 284
 285     ret = avctx->reget_buffer(avctx, &cc->frame);
 286     if (ret) {
 287         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
 288         return ret;
 289     }
 290     if (!avctx->frame_number)
 291         memset(cc->frame.data[0], 0, cc->frame.linesize[0] * avctx->height);
 292
 293     command = bytestream_get_byte(&buf);
 294     inst    = bytestream_get_byte(&buf);
 295     inst    &= CDG_MASK;
 296     buf += 2;  /// skipping 2 unneeded bytes
 297     bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
 298
 299     if ((command & CDG_MASK) == CDG_COMMAND) {
 300         switch (inst) {
 301         case CDG_INST_MEMORY_PRESET:
 302             if (!(cdg_data[1] & 0x0F))
 303                 memset(cc->frame.data[0], cdg_data[0] & 0x0F,
 304                        cc->frame.linesize[0] * CDG_FULL_HEIGHT);
 305             break;
 306         case CDG_INST_LOAD_PAL_LO:
 307         case CDG_INST_LOAD_PAL_HIGH:
 308             if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
 309                 av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
 310                 return AVERROR(EINVAL);
 311             }
 312
 313             cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
 314             break;
 315         case CDG_INST_BORDER_PRESET:
 316             cdg_border_preset(cc, cdg_data);
 317             break;
 318         case CDG_INST_TILE_BLOCK_XOR:
 319         case CDG_INST_TILE_BLOCK:
 320             if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
 321                 av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
 322                 return AVERROR(EINVAL);
 323             }
 324
 325             ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
 326             if (ret) {
 327                 av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
 328                 return ret;
 329             }
 330             break;
 331         case CDG_INST_SCROLL_PRESET:
 332         case CDG_INST_SCROLL_COPY:
 333             if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
 334                 av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
 335                 return AVERROR(EINVAL);
 336             }
 337
 338             cdg_init_frame(&new_frame);
 339             ret = ff_get_buffer(avctx, &new_frame);
 340             if (ret) {
 341                 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 342                 return ret;
 343             }
 344
 345             cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
 346             avctx->release_buffer(avctx, &cc->frame);
 347             cc->frame = new_frame;
 348             break;
 349         default:
 350             break;
 351         }
 352
 353         *got_frame = 1;
 354     } else {
 355         *got_frame = 0;
 356         buf_size   = 0;
 357     }
 358
 359     *(AVFrame *) data = cc->frame;
 360     return buf_size;
 361 }
 362
 363 static av_cold int cdg_decode_end(AVCodecContext *avctx)
 364 {
 365     CDGraphicsContext *cc = avctx->priv_data;
 366
 367     if (cc->frame.data[0])
 368         avctx->release_buffer(avctx, &cc->frame);
 369
 370     return 0;
 371 }
 372
 373 AVCodec ff_cdgraphics_decoder = {
 374     .name           = "cdgraphics",
 375     .type           = AVMEDIA_TYPE_VIDEO,
 376     .id             = AV_CODEC_ID_CDGRAPHICS,
 377     .priv_data_size = sizeof(CDGraphicsContext),
 378     .init           = cdg_decode_init,
 379     .close          = cdg_decode_end,
 380     .decode         = cdg_decode_frame,
 381     .capabilities   = CODEC_CAP_DR1,
 382     .long_name      = NULL_IF_CONFIG_SMALL("CD Graphics video"),
 383 };