yop.c
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1 /*
2  * Psygnosis YOP decoder
3  *
4  * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
5  * derived from the code by
6  * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
7  *
8  * This file is part of Libav.
9  *
10  * Libav is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * Libav is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with Libav; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 #include "libavutil/intreadwrite.h"
26 #include "libavutil/imgutils.h"
27 
28 #include "avcodec.h"
29 #include "get_bits.h"
30 
31 typedef struct YopDecContext {
34 
36  int first_color[2];
38  int row_pos;
39 
40  uint8_t *low_nibble;
41  uint8_t *srcptr;
42  uint8_t *dstptr;
43  uint8_t *dstbuf;
45 
46 // These tables are taken directly from:
47 // http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP
48 
55 static const uint8_t paint_lut[15][4] =
56  {{1, 2, 3, 4}, {1, 2, 0, 3},
57  {1, 2, 1, 3}, {1, 2, 2, 3},
58  {1, 0, 2, 3}, {1, 0, 0, 2},
59  {1, 0, 1, 2}, {1, 1, 2, 3},
60  {0, 1, 2, 3}, {0, 1, 0, 2},
61  {1, 1, 0, 2}, {0, 1, 1, 2},
62  {0, 0, 1, 2}, {0, 0, 0, 1},
63  {1, 1, 1, 2},
64  };
65 
70 static const int8_t motion_vector[16][2] =
71  {{-4, -4}, {-2, -4},
72  { 0, -4}, { 2, -4},
73  {-4, -2}, {-4, 0},
74  {-3, -3}, {-1, -3},
75  { 1, -3}, { 3, -3},
76  {-3, -1}, {-2, -2},
77  { 0, -2}, { 2, -2},
78  { 4, -2}, {-2, 0},
79  };
80 
82 {
83  YopDecContext *s = avctx->priv_data;
84  s->avctx = avctx;
85 
86  if (avctx->width & 1 || avctx->height & 1 ||
87  av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
88  av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");
89  return -1;
90  }
91 
92  avctx->pix_fmt = PIX_FMT_PAL8;
93 
94  s->num_pal_colors = avctx->extradata[0];
95  s->first_color[0] = avctx->extradata[1];
96  s->first_color[1] = avctx->extradata[2];
97 
98  if (s->num_pal_colors + s->first_color[0] > 256 ||
99  s->num_pal_colors + s->first_color[1] > 256) {
100  av_log(avctx, AV_LOG_ERROR,
101  "YOP: palette parameters invalid, header probably corrupt\n");
102  return AVERROR_INVALIDDATA;
103  }
104 
105  return 0;
106 }
107 
109 {
110  YopDecContext *s = avctx->priv_data;
111  if (s->frame.data[0])
112  avctx->release_buffer(avctx, &s->frame);
113  return 0;
114 }
115 
121 static void yop_paint_block(YopDecContext *s, int tag)
122 {
123  s->dstptr[0] = s->srcptr[0];
124  s->dstptr[1] = s->srcptr[paint_lut[tag][0]];
125  s->dstptr[s->frame.linesize[0]] = s->srcptr[paint_lut[tag][1]];
126  s->dstptr[s->frame.linesize[0] + 1] = s->srcptr[paint_lut[tag][2]];
127 
128  // The number of src bytes consumed is in the last part of the lut entry.
129  s->srcptr += paint_lut[tag][3];
130 }
131 
136 static int yop_copy_previous_block(YopDecContext *s, int copy_tag)
137 {
138  uint8_t *bufptr;
139 
140  // Calculate position for the copy source
141  bufptr = s->dstptr + motion_vector[copy_tag][0] +
142  s->frame.linesize[0] * motion_vector[copy_tag][1];
143  if (bufptr < s->dstbuf) {
145  "YOP: cannot decode, file probably corrupt\n");
146  return AVERROR_INVALIDDATA;
147  }
148 
149  s->dstptr[0] = bufptr[0];
150  s->dstptr[1] = bufptr[1];
151  s->dstptr[s->frame.linesize[0]] = bufptr[s->frame.linesize[0]];
152  s->dstptr[s->frame.linesize[0] + 1] = bufptr[s->frame.linesize[0] + 1];
153 
154  return 0;
155 }
156 
162 {
163  int ret;
164 
165  if (s->low_nibble) {
166  ret = *s->low_nibble & 0xf;
167  s->low_nibble = NULL;
168  }else {
169  s->low_nibble = s->srcptr++;
170  ret = *s->low_nibble >> 4;
171  }
172  return ret;
173 }
174 
179 {
180  // If we are advancing to the next row of macroblocks
181  if (s->row_pos == s->frame.linesize[0] - 2) {
182  s->dstptr += s->frame.linesize[0];
183  s->row_pos = 0;
184  }else {
185  s->row_pos += 2;
186  }
187  s->dstptr += 2;
188 }
189 
190 static int yop_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
191  AVPacket *avpkt)
192 {
193  YopDecContext *s = avctx->priv_data;
194  int tag, firstcolor, is_odd_frame;
195  int ret, i;
196  uint32_t *palette;
197 
198  if (s->frame.data[0])
199  avctx->release_buffer(avctx, &s->frame);
200 
201  ret = avctx->get_buffer(avctx, &s->frame);
202  if (ret < 0) {
203  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
204  return ret;
205  }
206 
207  s->frame.linesize[0] = avctx->width;
208 
209  s->dstbuf = s->frame.data[0];
210  s->dstptr = s->frame.data[0];
211  s->srcptr = avpkt->data + 4;
212  s->row_pos = 0;
213  s->low_nibble = NULL;
214 
215  is_odd_frame = avpkt->data[0];
216  firstcolor = s->first_color[is_odd_frame];
217  palette = (uint32_t *)s->frame.data[1];
218 
219  for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3)
220  palette[i + firstcolor] = (s->srcptr[0] << 18) |
221  (s->srcptr[1] << 10) |
222  (s->srcptr[2] << 2);
223 
224  s->frame.palette_has_changed = 1;
225 
226  while (s->dstptr - s->dstbuf <
227  avctx->width * avctx->height &&
228  s->srcptr - avpkt->data < avpkt->size) {
229 
230  tag = yop_get_next_nibble(s);
231 
232  if (tag != 0xf) {
233  yop_paint_block(s, tag);
234  }else {
235  tag = yop_get_next_nibble(s);
236  ret = yop_copy_previous_block(s, tag);
237  if (ret < 0) {
238  avctx->release_buffer(avctx, &s->frame);
239  return ret;
240  }
241  }
243  }
244 
245  *data_size = sizeof(AVFrame);
246  *(AVFrame *) data = s->frame;
247  return avpkt->size;
248 }
249 
251  .name = "yop",
252  .type = AVMEDIA_TYPE_VIDEO,
253  .id = CODEC_ID_YOP,
254  .priv_data_size = sizeof(YopDecContext),
258  .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),
259 };