1/* 2 * CD Graphics Video Decoder 3 * Copyright (c) 2009 Michael Tison 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 "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 66typedef struct CDGraphicsContext { 67 AVFrame *frame; 68 int hscroll; 69 int vscroll; 70} CDGraphicsContext; 71 72static av_cold int cdg_decode_init(AVCodecContext *avctx) 73{ 74 CDGraphicsContext *cc = avctx->priv_data; 75 76 cc->frame = av_frame_alloc(); 77 if (!cc->frame) 78 return AVERROR(ENOMEM); 79 80 avctx->width = CDG_FULL_WIDTH; 81 avctx->height = CDG_FULL_HEIGHT; 82 avctx->pix_fmt = AV_PIX_FMT_PAL8; 83 84 return 0; 85} 86 87static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data) 88{ 89 int y; 90 int lsize = cc->frame->linesize[0]; 91 uint8_t *buf = cc->frame->data[0]; 92 int color = data[0] & 0x0F; 93 94 if (!(data[1] & 0x0F)) { 95 /// fill the top and bottom borders 96 memset(buf, color, CDG_BORDER_HEIGHT * lsize); 97 memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize, 98 color, CDG_BORDER_HEIGHT * lsize); 99 100 /// fill the side borders 101 for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) { 102 memset(buf + y * lsize, color, CDG_BORDER_WIDTH); 103 memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize, 104 color, CDG_BORDER_WIDTH); 105 } 106 } 107} 108 109static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low) 110{ 111 uint8_t r, g, b; 112 uint16_t color; 113 int i; 114 int array_offset = low ? 0 : 8; 115 uint32_t *palette = (uint32_t *) cc->frame->data[1]; 116 117 for (i = 0; i < 8; i++) { 118 color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F); 119 r = ((color >> 8) & 0x000F) * 17; 120 g = ((color >> 4) & 0x000F) * 17; 121 b = ((color ) & 0x000F) * 17; 122 palette[i + array_offset] = 0xFFU << 24 | r << 16 | g << 8 | b; 123 } 124 cc->frame->palette_has_changed = 1; 125} 126 127static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b) 128{ 129 unsigned ci, ri; 130 int color; 131 int x, y; 132 int ai; 133 int stride = cc->frame->linesize[0]; 134 uint8_t *buf = cc->frame->data[0]; 135 136 ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll; 137 ci = (data[3] & 0x3F) * CDG_TILE_WIDTH + cc->hscroll; 138 139 if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT)) 140 return AVERROR(EINVAL); 141 if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH)) 142 return AVERROR(EINVAL); 143 144 for (y = 0; y < CDG_TILE_HEIGHT; y++) { 145 for (x = 0; x < CDG_TILE_WIDTH; x++) { 146 if (!((data[4 + y] >> (5 - x)) & 0x01)) 147 color = data[0] & 0x0F; 148 else 149 color = data[1] & 0x0F; 150 151 ai = ci + x + (stride * (ri + y)); 152 if (b) 153 color ^= buf[ai]; 154 buf[ai] = color; 155 } 156 } 157 158 return 0; 159} 160 161#define UP 2 162#define DOWN 1 163#define LEFT 2 164#define RIGHT 1 165 166static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out, 167 int in_tl_x, int in_tl_y, uint8_t *in, 168 int w, int h, int stride) 169{ 170 int y; 171 172 in += in_tl_x + in_tl_y * stride; 173 out += out_tl_x + out_tl_y * stride; 174 for (y = 0; y < h; y++) 175 memcpy(out + y * stride, in + y * stride, w); 176} 177 178static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out, 179 int color, int w, int h, int stride) 180{ 181 int y; 182 183 for (y = tl_y; y < tl_y + h; y++) 184 memset(out + tl_x + y * stride, color, w); 185} 186 187static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out, 188 int in_tl_x, int in_tl_y, uint8_t *in, 189 int color, int w, int h, int stride, int roll) 190{ 191 if (roll) { 192 cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y, 193 in, w, h, stride); 194 } else { 195 cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride); 196 } 197} 198 199static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data, 200 AVFrame *new_frame, int roll_over) 201{ 202 int color; 203 int hscmd, h_off, hinc, vscmd, v_off, vinc; 204 int y; 205 int stride = cc->frame->linesize[0]; 206 uint8_t *in = cc->frame->data[0]; 207 uint8_t *out = new_frame->data[0]; 208 209 color = data[0] & 0x0F; 210 hscmd = (data[1] & 0x30) >> 4; 211 vscmd = (data[2] & 0x30) >> 4; 212 213 h_off = FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH - 1); 214 v_off = FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1); 215 216 /// find the difference and save the offset for cdg_tile_block usage 217 hinc = h_off - cc->hscroll; 218 vinc = v_off - cc->vscroll; 219 cc->hscroll = h_off; 220 cc->vscroll = v_off; 221 222 if (vscmd == UP) 223 vinc -= 12; 224 if (vscmd == DOWN) 225 vinc += 12; 226 if (hscmd == LEFT) 227 hinc -= 6; 228 if (hscmd == RIGHT) 229 hinc += 6; 230 231 if (!hinc && !vinc) 232 return; 233 234 memcpy(new_frame->data[1], cc->frame->data[1], CDG_PALETTE_SIZE * 4); 235 236 for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++) 237 memcpy(out + FFMAX(0, hinc) + stride * y, 238 in + FFMAX(0, hinc) - hinc + (y - vinc) * stride, 239 FFMIN(stride + hinc, stride)); 240 241 if (vinc > 0) 242 cdg_fill_wrapper(0, 0, out, 243 0, CDG_FULL_HEIGHT - vinc, in, color, 244 stride, vinc, stride, roll_over); 245 else if (vinc < 0) 246 cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out, 247 0, 0, in, color, 248 stride, -1 * vinc, stride, roll_over); 249 250 if (hinc > 0) 251 cdg_fill_wrapper(0, 0, out, 252 CDG_FULL_WIDTH - hinc, 0, in, color, 253 hinc, CDG_FULL_HEIGHT, stride, roll_over); 254 else if (hinc < 0) 255 cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out, 256 0, 0, in, color, 257 -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over); 258 259} 260 261static int cdg_decode_frame(AVCodecContext *avctx, 262 void *data, int *got_frame, AVPacket *avpkt) 263{ 264 const uint8_t *buf = avpkt->data; 265 int buf_size = avpkt->size; 266 int ret; 267 uint8_t command, inst; 268 uint8_t cdg_data[CDG_DATA_SIZE] = {0}; 269 AVFrame *frame = data; 270 CDGraphicsContext *cc = avctx->priv_data; 271 272 if (buf_size < CDG_MINIMUM_PKT_SIZE) { 273 av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n"); 274 return AVERROR(EINVAL); 275 } 276 if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) { 277 av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n"); 278 return AVERROR(EINVAL); 279 } 280 281 if ((ret = ff_reget_buffer(avctx, cc->frame)) < 0) 282 return ret; 283 if (!avctx->frame_number) { 284 memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height); 285 memset(cc->frame->data[1], 0, AVPALETTE_SIZE); 286 } 287 288 command = bytestream_get_byte(&buf); 289 inst = bytestream_get_byte(&buf); 290 inst &= CDG_MASK; 291 buf += 2; /// skipping 2 unneeded bytes 292 293 if (buf_size > CDG_HEADER_SIZE) 294 bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE); 295 296 if ((command & CDG_MASK) == CDG_COMMAND) { 297 switch (inst) { 298 case CDG_INST_MEMORY_PRESET: 299 if (!(cdg_data[1] & 0x0F)) 300 memset(cc->frame->data[0], cdg_data[0] & 0x0F, 301 cc->frame->linesize[0] * CDG_FULL_HEIGHT); 302 break; 303 case CDG_INST_LOAD_PAL_LO: 304 case CDG_INST_LOAD_PAL_HIGH: 305 if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) { 306 av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n"); 307 return AVERROR(EINVAL); 308 } 309 310 cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO); 311 break; 312 case CDG_INST_BORDER_PRESET: 313 cdg_border_preset(cc, cdg_data); 314 break; 315 case CDG_INST_TILE_BLOCK_XOR: 316 case CDG_INST_TILE_BLOCK: 317 if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) { 318 av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n"); 319 return AVERROR(EINVAL); 320 } 321 322 ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR); 323 if (ret) { 324 av_log(avctx, AV_LOG_ERROR, "tile is out of range\n"); 325 return ret; 326 } 327 break; 328 case CDG_INST_SCROLL_PRESET: 329 case CDG_INST_SCROLL_COPY: 330 if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) { 331 av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n"); 332 return AVERROR(EINVAL); 333 } 334 335 if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0) 336 return ret; 337 338 cdg_scroll(cc, cdg_data, frame, inst == CDG_INST_SCROLL_COPY); 339 av_frame_unref(cc->frame); 340 ret = av_frame_ref(cc->frame, frame); 341 if (ret < 0) 342 return ret; 343 break; 344 default: 345 break; 346 } 347 348 if (!frame->data[0]) { 349 ret = av_frame_ref(frame, cc->frame); 350 if (ret < 0) 351 return ret; 352 } 353 *got_frame = 1; 354 } else { 355 *got_frame = 0; 356 } 357 358 return avpkt->size; 359} 360 361static av_cold int cdg_decode_end(AVCodecContext *avctx) 362{ 363 CDGraphicsContext *cc = avctx->priv_data; 364 365 av_frame_free(&cc->frame); 366 367 return 0; 368} 369 370AVCodec ff_cdgraphics_decoder = { 371 .name = "cdgraphics", 372 .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"), 373 .type = AVMEDIA_TYPE_VIDEO, 374 .id = AV_CODEC_ID_CDGRAPHICS, 375 .priv_data_size = sizeof(CDGraphicsContext), 376 .init = cdg_decode_init, 377 .close = cdg_decode_end, 378 .decode = cdg_decode_frame, 379 .capabilities = CODEC_CAP_DR1, 380}; 381