FFmpeg  1.2.12
c93.c
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1 /*
2  * Interplay C93 video decoder
3  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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 
25 typedef struct {
26  AVFrame pictures[2];
29 
30 typedef enum {
38  C93_NOOP = 0x0E,
39  C93_8X8_INTRA = 0x0F,
40 } C93BlockType;
41 
42 #define WIDTH 320
43 #define HEIGHT 192
44 
45 #define C93_HAS_PALETTE 0x01
46 #define C93_FIRST_FRAME 0x02
47 
49 {
50  C93DecoderContext * const c93 = avctx->priv_data;
51 
54  avctx->pix_fmt = AV_PIX_FMT_PAL8;
55  return 0;
56 }
57 
58 static av_cold int decode_end(AVCodecContext *avctx)
59 {
60  C93DecoderContext * const c93 = avctx->priv_data;
61 
62  if (c93->pictures[0].data[0])
63  avctx->release_buffer(avctx, &c93->pictures[0]);
64  if (c93->pictures[1].data[0])
65  avctx->release_buffer(avctx, &c93->pictures[1]);
66  return 0;
67 }
68 
69 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
70  uint8_t *from, int offset, int height, int stride)
71 {
72  int i;
73  int width = height;
74  int from_x = offset % WIDTH;
75  int from_y = offset / WIDTH;
76  int overflow = from_x + width - WIDTH;
77 
78  if (!from) {
79  /* silently ignoring predictive blocks in first frame */
80  return 0;
81  }
82 
83  if (from_y + height > HEIGHT) {
84  av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
85  offset);
86  return AVERROR_INVALIDDATA;
87  }
88 
89  if (overflow > 0) {
90  width -= overflow;
91  for (i = 0; i < height; i++) {
92  memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
93  }
94  }
95 
96  for (i = 0; i < height; i++) {
97  memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
98  }
99 
100  return 0;
101 }
102 
103 static inline void draw_n_color(uint8_t *out, int stride, int width,
104  int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
105 {
106  int x, y;
107  for (y = 0; y < height; y++) {
108  if (grps)
109  cols[0] = grps[3 * (y >> 1)];
110  for (x = 0; x < width; x++) {
111  if (grps)
112  cols[1]= grps[(x >> 1) + 1];
113  out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
114  col >>= bpp;
115  }
116  }
117 }
118 
119 static int decode_frame(AVCodecContext *avctx, void *data,
120  int *got_frame, AVPacket *avpkt)
121 {
122  const uint8_t *buf = avpkt->data;
123  int buf_size = avpkt->size;
124  C93DecoderContext * const c93 = avctx->priv_data;
125  AVFrame * const newpic = &c93->pictures[c93->currentpic];
126  AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
127  AVFrame *picture = data;
128  GetByteContext gb;
129  uint8_t *out;
130  int stride, ret, i, x, y, b, bt = 0;
131 
132  c93->currentpic ^= 1;
133 
134  newpic->reference = 3;
137  if ((ret = avctx->reget_buffer(avctx, newpic)) < 0) {
138  av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
139  return ret;
140  }
141 
142  stride = newpic->linesize[0];
143 
144  bytestream2_init(&gb, buf, buf_size);
145  b = bytestream2_get_byte(&gb);
146  if (b & C93_FIRST_FRAME) {
147  newpic->pict_type = AV_PICTURE_TYPE_I;
148  newpic->key_frame = 1;
149  } else {
150  newpic->pict_type = AV_PICTURE_TYPE_P;
151  newpic->key_frame = 0;
152  }
153 
154  for (y = 0; y < HEIGHT; y += 8) {
155  out = newpic->data[0] + y * stride;
156  for (x = 0; x < WIDTH; x += 8) {
157  uint8_t *copy_from = oldpic->data[0];
158  unsigned int offset, j;
159  uint8_t cols[4], grps[4];
160  C93BlockType block_type;
161 
162  if (!bt)
163  bt = bytestream2_get_byte(&gb);
164 
165  block_type= bt & 0x0F;
166  switch (block_type) {
167  case C93_8X8_FROM_PREV:
168  offset = bytestream2_get_le16(&gb);
169  if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
170  return ret;
171  break;
172 
173  case C93_4X4_FROM_CURR:
174  copy_from = newpic->data[0];
175  case C93_4X4_FROM_PREV:
176  for (j = 0; j < 8; j += 4) {
177  for (i = 0; i < 8; i += 4) {
178  int offset = bytestream2_get_le16(&gb);
179  int from_x = offset % WIDTH;
180  int from_y = offset / WIDTH;
181  if (block_type == C93_4X4_FROM_CURR && from_y == y+j &&
182  (FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) {
183  return AVERROR_INVALIDDATA;
184  }
185  if ((ret = copy_block(avctx, &out[j*stride+i],
186  copy_from, offset, 4, stride)) < 0)
187  return ret;
188  }
189  }
190  break;
191 
192  case C93_8X8_2COLOR:
193  bytestream2_get_buffer(&gb, cols, 2);
194  for (i = 0; i < 8; i++) {
195  draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
196  NULL, bytestream2_get_byte(&gb));
197  }
198 
199  break;
200 
201  case C93_4X4_2COLOR:
202  case C93_4X4_4COLOR:
203  case C93_4X4_4COLOR_GRP:
204  for (j = 0; j < 8; j += 4) {
205  for (i = 0; i < 8; i += 4) {
206  if (block_type == C93_4X4_2COLOR) {
207  bytestream2_get_buffer(&gb, cols, 2);
208  draw_n_color(out + i + j*stride, stride, 4, 4,
209  1, cols, NULL, bytestream2_get_le16(&gb));
210  } else if (block_type == C93_4X4_4COLOR) {
211  bytestream2_get_buffer(&gb, cols, 4);
212  draw_n_color(out + i + j*stride, stride, 4, 4,
213  2, cols, NULL, bytestream2_get_le32(&gb));
214  } else {
215  bytestream2_get_buffer(&gb, grps, 4);
216  draw_n_color(out + i + j*stride, stride, 4, 4,
217  1, cols, grps, bytestream2_get_le16(&gb));
218  }
219  }
220  }
221  break;
222 
223  case C93_NOOP:
224  break;
225 
226  case C93_8X8_INTRA:
227  for (j = 0; j < 8; j++)
228  bytestream2_get_buffer(&gb, out + j*stride, 8);
229  break;
230 
231  default:
232  av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
233  block_type, x, y);
234  return AVERROR_INVALIDDATA;
235  }
236  bt >>= 4;
237  out += 8;
238  }
239  }
240 
241  if (b & C93_HAS_PALETTE) {
242  uint32_t *palette = (uint32_t *) newpic->data[1];
243  for (i = 0; i < 256; i++) {
244  palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);
245  }
246  newpic->palette_has_changed = 1;
247  } else {
248  if (oldpic->data[1])
249  memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
250  }
251 
252  *picture = *newpic;
253  *got_frame = 1;
254 
255  return buf_size;
256 }
257 
259  .name = "c93",
260  .type = AVMEDIA_TYPE_VIDEO,
261  .id = AV_CODEC_ID_C93,
262  .priv_data_size = sizeof(C93DecoderContext),
263  .init = decode_init,
264  .close = decode_end,
265  .decode = decode_frame,
266  .capabilities = CODEC_CAP_DR1,
267  .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
268 };