2 * CD Graphics Video Decoder
3 * Copyright (c) 2009 Michael Tison
5 * This file is part of FFmpeg.
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.
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.
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
23 #include "bytestream.h"
27 * @brief CD Graphics Video Decoder
28 * @author Michael Tison
29 * @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
30 * @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
33 /// default screen sizes
34 #define CDG_FULL_WIDTH 300
35 #define CDG_FULL_HEIGHT 216
36 #define CDG_DISPLAY_WIDTH 294
37 #define CDG_DISPLAY_HEIGHT 204
38 #define CDG_BORDER_WIDTH 6
39 #define CDG_BORDER_HEIGHT 12
42 #define CDG_COMMAND 0x09
46 #define CDG_INST_MEMORY_PRESET 1
47 #define CDG_INST_BORDER_PRESET 2
48 #define CDG_INST_TILE_BLOCK 6
49 #define CDG_INST_SCROLL_PRESET 20
50 #define CDG_INST_SCROLL_COPY 24
51 #define CDG_INST_LOAD_PAL_LO 30
52 #define CDG_INST_LOAD_PAL_HIGH 31
53 #define CDG_INST_TILE_BLOCK_XOR 38
56 #define CDG_PACKET_SIZE 24
57 #define CDG_DATA_SIZE 16
58 #define CDG_TILE_HEIGHT 12
59 #define CDG_TILE_WIDTH 6
60 #define CDG_MINIMUM_PKT_SIZE 6
61 #define CDG_MINIMUM_SCROLL_SIZE 3
62 #define CDG_HEADER_SIZE 8
63 #define CDG_PALETTE_SIZE 16
65 typedef struct CDGraphicsContext {
71 static void cdg_init_frame(AVFrame *frame)
73 avcodec_get_frame_defaults(frame);
75 frame->buffer_hints = FF_BUFFER_HINTS_VALID |
76 FF_BUFFER_HINTS_READABLE |
77 FF_BUFFER_HINTS_PRESERVE |
78 FF_BUFFER_HINTS_REUSABLE;
81 static av_cold int cdg_decode_init(AVCodecContext *avctx)
83 CDGraphicsContext *cc = avctx->priv_data;
85 cdg_init_frame(&cc->frame);
87 avctx->width = CDG_FULL_WIDTH;
88 avctx->height = CDG_FULL_HEIGHT;
89 avctx->pix_fmt = PIX_FMT_PAL8;
94 static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
97 int lsize = cc->frame.linesize[0];
98 uint8_t *buf = cc->frame.data[0];
99 int color = data[0] & 0x0F;
101 if (!(data[1] & 0x0F)) {
102 /// fill the top and bottom borders
103 memset(buf, color, CDG_BORDER_HEIGHT * lsize);
104 memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
105 color, CDG_BORDER_HEIGHT * lsize);
107 /// fill the side borders
108 for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
109 memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
110 memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
111 color, CDG_BORDER_WIDTH);
116 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
121 int array_offset = low ? 0 : 8;
122 uint32_t *palette = (uint32_t *) cc->frame.data[1];
124 for (i = 0; i < 8; i++) {
125 color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
126 r = ((color >> 8) & 0x000F) * 17;
127 g = ((color >> 4) & 0x000F) * 17;
128 b = ((color ) & 0x000F) * 17;
129 palette[i + array_offset] = 0xFF << 24 | r << 16 | g << 8 | b;
131 cc->frame.palette_has_changed = 1;
134 static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
140 int stride = cc->frame.linesize[0];
141 uint8_t *buf = cc->frame.data[0];
143 ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
144 ci = (data[3] & 0x3F) * CDG_TILE_WIDTH + cc->hscroll;
146 if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
147 return AVERROR(EINVAL);
148 if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
149 return AVERROR(EINVAL);
151 for (y = 0; y < CDG_TILE_HEIGHT; y++) {
152 for (x = 0; x < CDG_TILE_WIDTH; x++) {
153 if (!((data[4 + y] >> (5 - x)) & 0x01))
154 color = data[0] & 0x0F;
156 color = data[1] & 0x0F;
158 ai = ci + x + (stride * (ri + y));
173 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
174 int in_tl_x, int in_tl_y, uint8_t *in,
175 int w, int h, int stride)
179 in += in_tl_x + in_tl_y * stride;
180 out += out_tl_x + out_tl_y * stride;
181 for (y = 0; y < h; y++)
182 memcpy(out + y * stride, in + y * stride, w);
185 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
186 int color, int w, int h, int stride)
190 for (y = tl_y; y < tl_y + h; y++)
191 memset(out + tl_x + y * stride, color, w);
194 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
195 int in_tl_x, int in_tl_y, uint8_t *in,
196 int color, int w, int h, int stride, int roll)
199 cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
202 cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
206 static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
207 AVFrame *new_frame, int roll_over)
210 int hscmd, h_off, hinc, vscmd, v_off, vinc;
212 int stride = cc->frame.linesize[0];
213 uint8_t *in = cc->frame.data[0];
214 uint8_t *out = new_frame->data[0];
216 color = data[0] & 0x0F;
217 hscmd = (data[1] & 0x30) >> 4;
218 vscmd = (data[2] & 0x30) >> 4;
220 h_off = FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH - 1);
221 v_off = FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);
223 /// find the difference and save the offset for cdg_tile_block usage
224 hinc = h_off - cc->hscroll;
225 vinc = v_off - cc->vscroll;
241 memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);
243 for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
244 memcpy(out + FFMAX(0, hinc) + stride * y,
245 in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
246 FFMIN(stride + hinc, stride));
249 cdg_fill_wrapper(0, 0, out,
250 0, CDG_FULL_HEIGHT - vinc, in, color,
251 stride, vinc, stride, roll_over);
253 cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
255 stride, -1 * vinc, stride, roll_over);
258 cdg_fill_wrapper(0, 0, out,
259 CDG_FULL_WIDTH - hinc, 0, in, color,
260 hinc, CDG_FULL_HEIGHT, stride, roll_over);
262 cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
264 -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
268 static int cdg_decode_frame(AVCodecContext *avctx,
269 void *data, int *data_size, AVPacket *avpkt)
271 const uint8_t *buf = avpkt->data;
272 int buf_size = avpkt->size;
274 uint8_t command, inst;
275 uint8_t cdg_data[CDG_DATA_SIZE];
277 CDGraphicsContext *cc = avctx->priv_data;
279 if (buf_size < CDG_MINIMUM_PKT_SIZE) {
280 av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
281 return AVERROR(EINVAL);
283 if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
284 av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
285 return AVERROR(EINVAL);
288 ret = avctx->reget_buffer(avctx, &cc->frame);
290 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
294 command = bytestream_get_byte(&buf);
295 inst = bytestream_get_byte(&buf);
297 buf += 2; /// skipping 2 unneeded bytes
298 bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
300 if ((command & CDG_MASK) == CDG_COMMAND) {
302 case CDG_INST_MEMORY_PRESET:
303 if (!(cdg_data[1] & 0x0F))
304 memset(cc->frame.data[0], cdg_data[0] & 0x0F,
305 cc->frame.linesize[0] * CDG_FULL_HEIGHT);
307 case CDG_INST_LOAD_PAL_LO:
308 case CDG_INST_LOAD_PAL_HIGH:
309 if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
310 av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
311 return AVERROR(EINVAL);
314 cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
316 case CDG_INST_BORDER_PRESET:
317 cdg_border_preset(cc, cdg_data);
319 case CDG_INST_TILE_BLOCK_XOR:
320 case CDG_INST_TILE_BLOCK:
321 if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
322 av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
323 return AVERROR(EINVAL);
326 ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
328 av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
332 case CDG_INST_SCROLL_PRESET:
333 case CDG_INST_SCROLL_COPY:
334 if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
335 av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
336 return AVERROR(EINVAL);
339 cdg_init_frame(&new_frame);
340 ret = avctx->get_buffer(avctx, &new_frame);
342 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
346 cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
347 avctx->release_buffer(avctx, &cc->frame);
348 cc->frame = new_frame;
354 *data_size = sizeof(AVFrame);
360 *(AVFrame *) data = cc->frame;
364 static av_cold int cdg_decode_end(AVCodecContext *avctx)
366 CDGraphicsContext *cc = avctx->priv_data;
368 if (cc->frame.data[0])
369 avctx->release_buffer(avctx, &cc->frame);
374 AVCodec ff_cdgraphics_decoder = {
375 .name = "cdgraphics",
376 .type = AVMEDIA_TYPE_VIDEO,
377 .id = AV_CODEC_ID_CDGRAPHICS,
378 .priv_data_size = sizeof(CDGraphicsContext),
379 .init = cdg_decode_init,
380 .close = cdg_decode_end,
381 .decode = cdg_decode_frame,
382 .capabilities = CODEC_CAP_DR1,
383 .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),