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"
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
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
43 #define CDG_COMMAND 0x09
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_TRANSPARENT_COL 28
53 #define CDG_INST_LOAD_PAL_LO 30
54 #define CDG_INST_LOAD_PAL_HIGH 31
55 #define CDG_INST_TILE_BLOCK_XOR 38
58 #define CDG_PACKET_SIZE 24
59 #define CDG_DATA_SIZE 16
60 #define CDG_TILE_HEIGHT 12
61 #define CDG_TILE_WIDTH 6
62 #define CDG_MINIMUM_PKT_SIZE 6
63 #define CDG_MINIMUM_SCROLL_SIZE 3
64 #define CDG_HEADER_SIZE 8
65 #define CDG_PALETTE_SIZE 16
67 typedef struct CDGraphicsContext {
75 static av_cold int cdg_decode_init(AVCodecContext *avctx)
77 CDGraphicsContext *cc = avctx->priv_data;
79 cc->frame = av_frame_alloc();
81 return AVERROR(ENOMEM);
82 cc->transparency = -1;
84 avctx->width = CDG_FULL_WIDTH;
85 avctx->height = CDG_FULL_HEIGHT;
86 avctx->pix_fmt = AV_PIX_FMT_PAL8;
91 static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
94 int lsize = cc->frame->linesize[0];
95 uint8_t *buf = cc->frame->data[0];
96 int color = data[0] & 0x0F;
98 if (!(data[1] & 0x0F)) {
99 /// fill the top and bottom borders
100 memset(buf, color, CDG_BORDER_HEIGHT * lsize);
101 memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
102 color, CDG_BORDER_HEIGHT * lsize);
104 /// fill the side borders
105 for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
106 memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
107 memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
108 color, CDG_BORDER_WIDTH);
113 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
118 int array_offset = low ? 0 : 8;
119 uint32_t *palette = (uint32_t *) cc->frame->data[1];
121 for (i = 0; i < 8; i++) {
122 color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
123 r = ((color >> 8) & 0x000F) * 17;
124 g = ((color >> 4) & 0x000F) * 17;
125 b = ((color ) & 0x000F) * 17;
126 palette[i + array_offset] = 0xFFU << 24 | r << 16 | g << 8 | b;
127 if (cc->transparency >= 0)
128 palette[cc->transparency] &= 0xFFFFFF;
130 cc->frame->palette_has_changed = 1;
133 static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
139 int stride = cc->frame->linesize[0];
140 uint8_t *buf = cc->frame->data[0];
142 ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
143 ci = (data[3] & 0x3F) * CDG_TILE_WIDTH + cc->hscroll;
145 if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
146 return AVERROR(EINVAL);
147 if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
148 return AVERROR(EINVAL);
150 for (y = 0; y < CDG_TILE_HEIGHT; y++) {
151 for (x = 0; x < CDG_TILE_WIDTH; x++) {
152 if (!((data[4 + y] >> (5 - x)) & 0x01))
153 color = data[0] & 0x0F;
155 color = data[1] & 0x0F;
157 ai = ci + x + (stride * (ri + y));
172 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
173 int in_tl_x, int in_tl_y, uint8_t *in,
174 int w, int h, int stride)
178 in += in_tl_x + in_tl_y * stride;
179 out += out_tl_x + out_tl_y * stride;
180 for (y = 0; y < h; y++)
181 memcpy(out + y * stride, in + y * stride, w);
184 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
185 int color, int w, int h, int stride)
189 for (y = tl_y; y < tl_y + h; y++)
190 memset(out + tl_x + y * stride, color, w);
193 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
194 int in_tl_x, int in_tl_y, uint8_t *in,
195 int color, int w, int h, int stride, int roll)
198 cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
201 cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
205 static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
206 AVFrame *new_frame, int roll_over)
209 int hscmd, h_off, hinc, vscmd, v_off, vinc;
211 int stride = cc->frame->linesize[0];
212 uint8_t *in = cc->frame->data[0];
213 uint8_t *out = new_frame->data[0];
215 color = data[0] & 0x0F;
216 hscmd = (data[1] & 0x30) >> 4;
217 vscmd = (data[2] & 0x30) >> 4;
219 h_off = FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH - 1);
220 v_off = FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
222 /// find the difference and save the offset for cdg_tile_block usage
223 hinc = h_off - cc->hscroll;
224 vinc = v_off - cc->vscroll;
240 memcpy(new_frame->data[1], cc->frame->data[1], CDG_PALETTE_SIZE * 4);
242 for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
243 memcpy(out + FFMAX(0, hinc) + stride * y,
244 in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
245 FFMIN(stride + hinc, stride));
248 cdg_fill_wrapper(0, 0, out,
249 0, CDG_FULL_HEIGHT - vinc, in, color,
250 stride, vinc, stride, roll_over);
252 cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
254 stride, -1 * vinc, stride, roll_over);
257 cdg_fill_wrapper(0, 0, out,
258 CDG_FULL_WIDTH - hinc, 0, in, color,
259 hinc, CDG_FULL_HEIGHT, stride, roll_over);
261 cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
263 -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
267 static int cdg_decode_frame(AVCodecContext *avctx,
268 void *data, int *got_frame, AVPacket *avpkt)
271 int buf_size = avpkt->size;
273 uint8_t command, inst;
274 uint8_t cdg_data[CDG_DATA_SIZE] = {0};
275 AVFrame *frame = data;
276 CDGraphicsContext *cc = avctx->priv_data;
278 if (buf_size < CDG_MINIMUM_PKT_SIZE) {
279 av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
280 return AVERROR(EINVAL);
282 if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
283 av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
284 return AVERROR(EINVAL);
287 bytestream2_init(&gb, avpkt->data, avpkt->size);
289 if ((ret = ff_reget_buffer(avctx, cc->frame)) < 0)
292 memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
293 memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
297 command = bytestream2_get_byte(&gb);
298 inst = bytestream2_get_byte(&gb);
300 bytestream2_skip(&gb, 2);
301 bytestream2_get_buffer(&gb, cdg_data, sizeof(cdg_data));
303 if ((command & CDG_MASK) == CDG_COMMAND) {
305 case CDG_INST_MEMORY_PRESET:
306 if (!(cdg_data[1] & 0x0F))
307 memset(cc->frame->data[0], cdg_data[0] & 0x0F,
308 cc->frame->linesize[0] * CDG_FULL_HEIGHT);
310 case CDG_INST_LOAD_PAL_LO:
311 case CDG_INST_LOAD_PAL_HIGH:
312 if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
313 av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
314 return AVERROR(EINVAL);
317 cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
319 case CDG_INST_BORDER_PRESET:
320 cdg_border_preset(cc, cdg_data);
322 case CDG_INST_TILE_BLOCK_XOR:
323 case CDG_INST_TILE_BLOCK:
324 if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
325 av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
326 return AVERROR(EINVAL);
329 ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
331 av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
335 case CDG_INST_SCROLL_PRESET:
336 case CDG_INST_SCROLL_COPY:
337 if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
338 av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
339 return AVERROR(EINVAL);
342 if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
345 cdg_scroll(cc, cdg_data, frame, inst == CDG_INST_SCROLL_COPY);
346 av_frame_unref(cc->frame);
347 ret = av_frame_ref(cc->frame, frame);
351 case CDG_INST_TRANSPARENT_COL:
352 cc->transparency = cdg_data[0] & 0xF;
358 if (!frame->data[0]) {
359 ret = av_frame_ref(frame, cc->frame);
371 static av_cold int cdg_decode_end(AVCodecContext *avctx)
373 CDGraphicsContext *cc = avctx->priv_data;
375 av_frame_free(&cc->frame);
380 AVCodec ff_cdgraphics_decoder = {
381 .name = "cdgraphics",
382 .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
383 .type = AVMEDIA_TYPE_VIDEO,
384 .id = AV_CODEC_ID_CDGRAPHICS,
385 .priv_data_size = sizeof(CDGraphicsContext),
386 .init = cdg_decode_init,
387 .close = cdg_decode_end,
388 .decode = cdg_decode_frame,
389 .capabilities = AV_CODEC_CAP_DR1,