Libav
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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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 "internal.h"
25 
26 typedef struct {
27  AVFrame *pictures[2];
30 
31 typedef enum {
39  C93_NOOP = 0x0E,
40  C93_8X8_INTRA = 0x0F,
41 } C93BlockType;
42 
43 #define WIDTH 320
44 #define HEIGHT 192
45 
46 #define C93_HAS_PALETTE 0x01
47 #define C93_FIRST_FRAME 0x02
48 
49 static av_cold int decode_end(AVCodecContext *avctx)
50 {
51  C93DecoderContext * const c93 = avctx->priv_data;
52 
53  av_frame_free(&c93->pictures[0]);
54  av_frame_free(&c93->pictures[1]);
55 
56  return 0;
57 }
58 
60 {
61  C93DecoderContext *s = avctx->priv_data;
62  avctx->pix_fmt = AV_PIX_FMT_PAL8;
63 
64  s->pictures[0] = av_frame_alloc();
65  s->pictures[1] = av_frame_alloc();
66  if (!s->pictures[0] || !s->pictures[1]) {
67  decode_end(avctx);
68  return AVERROR(ENOMEM);
69  }
70 
71  return 0;
72 }
73 
74 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
75  uint8_t *from, int offset, int height, int stride)
76 {
77  int i;
78  int width = height;
79  int from_x = offset % WIDTH;
80  int from_y = offset / WIDTH;
81  int overflow = from_x + width - WIDTH;
82 
83  if (!from) {
84  /* silently ignoring predictive blocks in first frame */
85  return 0;
86  }
87 
88  if (from_y + height > HEIGHT) {
89  av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
90  offset);
91  return AVERROR_INVALIDDATA;
92  }
93 
94  if (overflow > 0) {
95  width -= overflow;
96  for (i = 0; i < height; i++) {
97  memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
98  }
99  }
100 
101  for (i = 0; i < height; i++) {
102  memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
103  }
104 
105  return 0;
106 }
107 
108 static inline void draw_n_color(uint8_t *out, int stride, int width,
109  int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
110 {
111  int x, y;
112  for (y = 0; y < height; y++) {
113  if (grps)
114  cols[0] = grps[3 * (y >> 1)];
115  for (x = 0; x < width; x++) {
116  if (grps)
117  cols[1]= grps[(x >> 1) + 1];
118  out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
119  col >>= bpp;
120  }
121  }
122 }
123 
124 static int decode_frame(AVCodecContext *avctx, void *data,
125  int *got_frame, AVPacket *avpkt)
126 {
127  const uint8_t *buf = avpkt->data;
128  int buf_size = avpkt->size;
129  C93DecoderContext * const c93 = avctx->priv_data;
130  AVFrame * const newpic = c93->pictures[c93->currentpic];
131  AVFrame * const oldpic = c93->pictures[c93->currentpic^1];
132  GetByteContext gb;
133  uint8_t *out;
134  int stride, ret, i, x, y, b, bt = 0;
135 
136  c93->currentpic ^= 1;
137 
138  if ((ret = ff_reget_buffer(avctx, newpic)) < 0) {
139  av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
140  return ret;
141  }
142 
143  stride = newpic->linesize[0];
144 
145  bytestream2_init(&gb, buf, buf_size);
146  b = bytestream2_get_byte(&gb);
147  if (b & C93_FIRST_FRAME) {
148  newpic->pict_type = AV_PICTURE_TYPE_I;
149  newpic->key_frame = 1;
150  } else {
151  newpic->pict_type = AV_PICTURE_TYPE_P;
152  newpic->key_frame = 0;
153  }
154 
155  for (y = 0; y < HEIGHT; y += 8) {
156  out = newpic->data[0] + y * stride;
157  for (x = 0; x < WIDTH; x += 8) {
158  uint8_t *copy_from = oldpic->data[0];
159  unsigned int offset, j;
160  uint8_t cols[4], grps[4];
161  C93BlockType block_type;
162 
163  if (!bt)
164  bt = bytestream2_get_byte(&gb);
165 
166  block_type= bt & 0x0F;
167  switch (block_type) {
168  case C93_8X8_FROM_PREV:
169  offset = bytestream2_get_le16(&gb);
170  if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
171  return ret;
172  break;
173 
174  case C93_4X4_FROM_CURR:
175  copy_from = newpic->data[0];
176  case C93_4X4_FROM_PREV:
177  for (j = 0; j < 8; j += 4) {
178  for (i = 0; i < 8; i += 4) {
179  offset = bytestream2_get_le16(&gb);
180  if ((ret = copy_block(avctx, &out[j*stride+i],
181  copy_from, offset, 4, stride)) < 0)
182  return ret;
183  }
184  }
185  break;
186 
187  case C93_8X8_2COLOR:
188  bytestream2_get_buffer(&gb, cols, 2);
189  for (i = 0; i < 8; i++) {
190  draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
191  NULL, bytestream2_get_byte(&gb));
192  }
193 
194  break;
195 
196  case C93_4X4_2COLOR:
197  case C93_4X4_4COLOR:
198  case C93_4X4_4COLOR_GRP:
199  for (j = 0; j < 8; j += 4) {
200  for (i = 0; i < 8; i += 4) {
201  if (block_type == C93_4X4_2COLOR) {
202  bytestream2_get_buffer(&gb, cols, 2);
203  draw_n_color(out + i + j*stride, stride, 4, 4,
204  1, cols, NULL, bytestream2_get_le16(&gb));
205  } else if (block_type == C93_4X4_4COLOR) {
206  bytestream2_get_buffer(&gb, cols, 4);
207  draw_n_color(out + i + j*stride, stride, 4, 4,
208  2, cols, NULL, bytestream2_get_le32(&gb));
209  } else {
210  bytestream2_get_buffer(&gb, grps, 4);
211  draw_n_color(out + i + j*stride, stride, 4, 4,
212  1, cols, grps, bytestream2_get_le16(&gb));
213  }
214  }
215  }
216  break;
217 
218  case C93_NOOP:
219  break;
220 
221  case C93_8X8_INTRA:
222  for (j = 0; j < 8; j++)
223  bytestream2_get_buffer(&gb, out + j*stride, 8);
224  break;
225 
226  default:
227  av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
228  block_type, x, y);
229  return AVERROR_INVALIDDATA;
230  }
231  bt >>= 4;
232  out += 8;
233  }
234  }
235 
236  if (b & C93_HAS_PALETTE) {
237  uint32_t *palette = (uint32_t *) newpic->data[1];
238  for (i = 0; i < 256; i++) {
239  palette[i] = bytestream2_get_be24(&gb);
240  }
241  newpic->palette_has_changed = 1;
242  } else {
243  if (oldpic->data[1])
244  memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
245  }
246 
247  if ((ret = av_frame_ref(data, newpic)) < 0)
248  return ret;
249  *got_frame = 1;
250 
251  return buf_size;
252 }
253 
255  .name = "c93",
256  .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
257  .type = AVMEDIA_TYPE_VIDEO,
258  .id = AV_CODEC_ID_C93,
259  .priv_data_size = sizeof(C93DecoderContext),
260  .init = decode_init,
261  .close = decode_end,
262  .decode = decode_frame,
263  .capabilities = CODEC_CAP_DR1,
264 };