FFmpeg: libavcodec/cdgraphics.c Source File

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libavcodec

cdgraphics.c

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1 /*

2 * CD Graphics Video Decoder

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 */

22 #include "avcodec.h"

23 #include "bytestream.h"

24 #include "internal.h"

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 */

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

42 /// masks

43 #define CDG_COMMAND 0x09

44 #define CDG_MASK 0x3F

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

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

66 typedef struct CDGraphicsContext {

67 AVFrame *frame;

68 int hscroll;

69 int vscroll;

70 } CDGraphicsContext;

72 static av_cold int cdg_decode_init(AVCodecContext *avctx)

73 {

74 CDGraphicsContext *cc = avctx->priv_data;

76 cc->frame = av_frame_alloc();

77 if (!cc->frame)

78 return AVERROR(ENOMEM);

80 avctx->width = CDG_FULL_WIDTH;

81 avctx->height = CDG_FULL_HEIGHT;

82 avctx->pix_fmt = AV_PIX_FMT_PAL8;

84 return 0;

85 }

87 static 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;

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);

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

109 static 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

127 static 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

166 static 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

178 static 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

187 static 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

199 static 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

261 static int cdg_decode_frame(AVCodecContext *avctx,

262 void *data, int *got_frame, AVPacket *avpkt)

263 {

264 GetByteContext gb;

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 bytestream2_init(&gb, avpkt->data, avpkt->size);

282

283 if ((ret = ff_reget_buffer(avctx, cc->frame)) < 0)

284 return ret;

285 if (!avctx->frame_number) {

286 memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);

287 memset(cc->frame->data[1], 0, AVPALETTE_SIZE);

288 }

289

290 command = bytestream2_get_byte(&gb);

291 inst = bytestream2_get_byte(&gb);

292 inst &= CDG_MASK;

293 bytestream2_skip(&gb, 2);

294 bytestream2_get_buffer(&gb, cdg_data, sizeof(cdg_data));

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

361 static 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

370 AVCodec 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 };

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