• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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 "codec_internal.h"
25 #include "internal.h"
26 
27 /**
28  * @file
29  * @brief CD Graphics Video Decoder
30  * @author Michael Tison
31  * @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
32  * @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
33  */
34 
35 /// default screen sizes
36 #define CDG_FULL_WIDTH           300
37 #define CDG_FULL_HEIGHT          216
38 #define CDG_DISPLAY_WIDTH        294
39 #define CDG_DISPLAY_HEIGHT       204
40 #define CDG_BORDER_WIDTH           6
41 #define CDG_BORDER_HEIGHT         12
42 
43 /// masks
44 #define CDG_COMMAND             0x09
45 #define CDG_MASK                0x3F
46 
47 /// instruction codes
48 #define CDG_INST_MEMORY_PRESET     1
49 #define CDG_INST_BORDER_PRESET     2
50 #define CDG_INST_TILE_BLOCK        6
51 #define CDG_INST_SCROLL_PRESET    20
52 #define CDG_INST_SCROLL_COPY      24
53 #define CDG_INST_TRANSPARENT_COL  28
54 #define CDG_INST_LOAD_PAL_LO      30
55 #define CDG_INST_LOAD_PAL_HIGH    31
56 #define CDG_INST_TILE_BLOCK_XOR   38
57 
58 /// data sizes
59 #define CDG_PACKET_SIZE           24
60 #define CDG_DATA_SIZE             16
61 #define CDG_TILE_HEIGHT           12
62 #define CDG_TILE_WIDTH             6
63 #define CDG_MINIMUM_PKT_SIZE       6
64 #define CDG_MINIMUM_SCROLL_SIZE    3
65 #define CDG_HEADER_SIZE            8
66 #define CDG_PALETTE_SIZE          16
67 
68 typedef struct CDGraphicsContext {
69     AVFrame *frame;
70     int hscroll;
71     int vscroll;
72     uint8_t alpha[CDG_PALETTE_SIZE];
73     int cleared;
74 } CDGraphicsContext;
75 
cdg_decode_init(AVCodecContext * avctx)76 static av_cold int cdg_decode_init(AVCodecContext *avctx)
77 {
78     CDGraphicsContext *cc = avctx->priv_data;
79 
80     cc->frame = av_frame_alloc();
81     if (!cc->frame)
82         return AVERROR(ENOMEM);
83 
84     for (int i = 0; i < CDG_PALETTE_SIZE; i++)
85         cc->alpha[i] = 0xFFU;
86 
87     avctx->pix_fmt = AV_PIX_FMT_PAL8;
88     return ff_set_dimensions(avctx, CDG_FULL_WIDTH, CDG_FULL_HEIGHT);
89 }
90 
cdg_border_preset(CDGraphicsContext * cc,uint8_t * data)91 static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
92 {
93     int y;
94     int lsize    = cc->frame->linesize[0];
95     uint8_t *buf = cc->frame->data[0];
96     int color    = data[0] & 0x0F;
97 
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);
103 
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);
109         }
110     }
111 }
112 
cdg_load_palette(CDGraphicsContext * cc,uint8_t * data,int low)113 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
114 {
115     uint8_t r, g, b;
116     uint16_t color;
117     int i;
118     int array_offset  = low ? 0 : 8;
119     uint32_t *palette = (uint32_t *) cc->frame->data[1];
120 
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] = (uint32_t)cc->alpha[i + array_offset] << 24 | r << 16 | g << 8 | b;
127     }
128     cc->frame->palette_has_changed = 1;
129 }
130 
cdg_tile_block(CDGraphicsContext * cc,uint8_t * data,int b)131 static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
132 {
133     unsigned ci, ri;
134     int color;
135     int x, y;
136     int ai;
137     int stride   = cc->frame->linesize[0];
138     uint8_t *buf = cc->frame->data[0];
139 
140     ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
141     ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;
142 
143     if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
144         return AVERROR(EINVAL);
145     if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
146         return AVERROR(EINVAL);
147 
148     for (y = 0; y < CDG_TILE_HEIGHT; y++) {
149         for (x = 0; x < CDG_TILE_WIDTH; x++) {
150             if (!((data[4 + y] >> (5 - x)) & 0x01))
151                 color = data[0] & 0x0F;
152             else
153                 color = data[1] & 0x0F;
154 
155             ai = ci + x + (stride * (ri + y));
156             if (b)
157                 color ^= buf[ai];
158             buf[ai] = color;
159         }
160     }
161 
162     return 0;
163 }
164 
165 #define UP    2
166 #define DOWN  1
167 #define LEFT  2
168 #define RIGHT 1
169 
cdg_copy_rect_buf(int out_tl_x,int out_tl_y,uint8_t * out,int in_tl_x,int in_tl_y,uint8_t * in,int w,int h,int stride)170 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
171                               int in_tl_x, int in_tl_y, uint8_t *in,
172                               int w, int h, int stride)
173 {
174     int y;
175 
176     in  += in_tl_x  + in_tl_y  * stride;
177     out += out_tl_x + out_tl_y * stride;
178     for (y = 0; y < h; y++)
179         memcpy(out + y * stride, in + y * stride, w);
180 }
181 
cdg_fill_rect_preset(int tl_x,int tl_y,uint8_t * out,int color,int w,int h,int stride)182 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
183                                  int color, int w, int h, int stride)
184 {
185     int y;
186 
187     for (y = tl_y; y < tl_y + h; y++)
188         memset(out + tl_x + y * stride, color, w);
189 }
190 
cdg_fill_wrapper(int out_tl_x,int out_tl_y,uint8_t * out,int in_tl_x,int in_tl_y,uint8_t * in,int color,int w,int h,int stride,int roll)191 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
192                              int in_tl_x, int in_tl_y, uint8_t *in,
193                              int color, int w, int h, int stride, int roll)
194 {
195     if (roll) {
196         cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
197                           in, w, h, stride);
198     } else {
199         cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
200     }
201 }
202 
cdg_scroll(CDGraphicsContext * cc,uint8_t * data,AVFrame * new_frame,int roll_over)203 static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
204                        AVFrame *new_frame, int roll_over)
205 {
206     int color;
207     int hscmd, h_off, hinc, vscmd, v_off, vinc;
208     int y;
209     int stride   = cc->frame->linesize[0];
210     uint8_t *in  = cc->frame->data[0];
211     uint8_t *out = new_frame->data[0];
212 
213     color =  data[0] & 0x0F;
214     hscmd = (data[1] & 0x30) >> 4;
215     vscmd = (data[2] & 0x30) >> 4;
216 
217     h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
218     v_off =  FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
219 
220     /// find the difference and save the offset for cdg_tile_block usage
221     hinc = h_off - cc->hscroll;
222     vinc = cc->vscroll - v_off;
223     cc->hscroll = h_off;
224     cc->vscroll = v_off;
225 
226     if (vscmd == UP)
227         vinc -= 12;
228     if (vscmd == DOWN)
229         vinc += 12;
230     if (hscmd == LEFT)
231         hinc -= 6;
232     if (hscmd == RIGHT)
233         hinc += 6;
234 
235     if (!hinc && !vinc)
236         return;
237 
238     memcpy(new_frame->data[1], cc->frame->data[1], CDG_PALETTE_SIZE * 4);
239 
240     for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
241         memcpy(out + FFMAX(0, hinc) + stride * y,
242                in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
243                FFABS(stride) - FFABS(hinc));
244 
245     if (vinc > 0)
246         cdg_fill_wrapper(0, 0, out,
247                          0, CDG_FULL_HEIGHT - vinc, in, color,
248                          stride, vinc, stride, roll_over);
249     else if (vinc < 0)
250         cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
251                          0, 0, in, color,
252                          stride, -1 * vinc, stride, roll_over);
253 
254     if (hinc > 0)
255         cdg_fill_wrapper(0, 0, out,
256                          CDG_FULL_WIDTH - hinc, 0, in, color,
257                          hinc, CDG_FULL_HEIGHT, stride, roll_over);
258     else if (hinc < 0)
259         cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
260                          0, 0, in, color,
261                          -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
262 
263 }
264 
cdg_decode_frame(AVCodecContext * avctx,AVFrame * frame,int * got_frame,AVPacket * avpkt)265 static int cdg_decode_frame(AVCodecContext *avctx, AVFrame *frame,
266                             int *got_frame, AVPacket *avpkt)
267 {
268     GetByteContext gb;
269     int buf_size       = avpkt->size;
270     int ret;
271     uint8_t command, inst;
272     uint8_t cdg_data[CDG_DATA_SIZE] = {0};
273     CDGraphicsContext *cc = avctx->priv_data;
274 
275     if (buf_size < CDG_MINIMUM_PKT_SIZE) {
276         av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
277         return AVERROR(EINVAL);
278     }
279     if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
280         av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
281         return AVERROR(EINVAL);
282     }
283 
284     bytestream2_init(&gb, avpkt->data, avpkt->size);
285 
286     if ((ret = ff_reget_buffer(avctx, cc->frame, 0)) < 0)
287         return ret;
288     if (!cc->cleared) {
289         memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
290         memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
291         cc->cleared = 1;
292     }
293 
294     command = bytestream2_get_byte(&gb);
295     inst    = bytestream2_get_byte(&gb);
296     inst    &= CDG_MASK;
297     bytestream2_skip(&gb, 2);
298     bytestream2_get_buffer(&gb, cdg_data, sizeof(cdg_data));
299 
300     if ((command & CDG_MASK) == CDG_COMMAND) {
301         switch (inst) {
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);
306             break;
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);
312             }
313 
314             cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
315             break;
316         case CDG_INST_BORDER_PRESET:
317             cdg_border_preset(cc, cdg_data);
318             break;
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);
324             }
325 
326             ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
327             if (ret) {
328                 av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
329                 return ret;
330             }
331             break;
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);
337             }
338 
339             if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
340                 return ret;
341 
342             cdg_scroll(cc, cdg_data, frame, inst == CDG_INST_SCROLL_COPY);
343             av_frame_unref(cc->frame);
344             ret = av_frame_ref(cc->frame, frame);
345             if (ret < 0)
346                 return ret;
347             break;
348         case CDG_INST_TRANSPARENT_COL:
349             for (int i = 0; i < CDG_PALETTE_SIZE; i++)
350                 cc->alpha[i] = 255 - ((cdg_data[i] & 0x3f) << 2);
351             break;
352         default:
353             break;
354         }
355 
356         if (!frame->data[0]) {
357             ret = av_frame_ref(frame, cc->frame);
358             if (ret < 0)
359                 return ret;
360         }
361         *got_frame = 1;
362     } else {
363         *got_frame = 0;
364     }
365 
366     return avpkt->size;
367 }
368 
cdg_decode_flush(AVCodecContext * avctx)369 static void cdg_decode_flush(AVCodecContext *avctx)
370 {
371     CDGraphicsContext *cc = avctx->priv_data;
372 
373     if (!cc->frame->data[0])
374         return;
375 
376     memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
377     if (!avctx->frame_number)
378         memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
379 }
380 
cdg_decode_end(AVCodecContext * avctx)381 static av_cold int cdg_decode_end(AVCodecContext *avctx)
382 {
383     CDGraphicsContext *cc = avctx->priv_data;
384 
385     av_frame_free(&cc->frame);
386 
387     return 0;
388 }
389 
390 const FFCodec ff_cdgraphics_decoder = {
391     .p.name         = "cdgraphics",
392     .p.long_name    = NULL_IF_CONFIG_SMALL("CD Graphics video"),
393     .p.type         = AVMEDIA_TYPE_VIDEO,
394     .p.id           = AV_CODEC_ID_CDGRAPHICS,
395     .priv_data_size = sizeof(CDGraphicsContext),
396     .init           = cdg_decode_init,
397     .close          = cdg_decode_end,
398     FF_CODEC_DECODE_CB(cdg_decode_frame),
399     .flush          = cdg_decode_flush,
400     .p.capabilities = AV_CODEC_CAP_DR1,
401     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
402 };
403